Speed Management Hub
Frequently Asked Questions
1. Introduction to Speed Management
Speed management involves various techniques to reduce/modify the speed of road users, usually motorized vehicles. The purpose is to ensure that speeds are safe for all road users to avoid injuries and death, as well as to improve traffic flow, reduce noise and air pollution, and decrease climate change impacts of road transport.
The management of speed can be achieved through the use of appropriate speed limits, provision of road infrastructure to support these limits, police enforcement, education and community engagement, and vehicle technologies. A mixture of these approaches is often used and the most effective. Speed management should occur as part of a structured, consistent approach that covers the entire road network of interest. However, in many instances, localized changes to speed may be required, often in response to local safety issues.
Under the Safe System approach, safety is the key objective when managing speeds, with a requirement to set and encourage speeds that avoid death and serious injury for all road users, particularly the most vulnerable (including pedestrians and cyclists). Decisions on the appropriate speed often include reference to other societal outcomes besides safety mentioned above, including vehicle journey time, noise and emissions.
Learn more about speed management from this WHO guide and this OECD study.
The Safe System approach is a human centric approach in the road transport system which highlights that deaths and serious injuries on our roads are unacceptable and avoidable, and this should dictate the design, use and operation of our road networks. The approach has been adopted by key global organizations (including the World Bank, WHO, United Nations, PIARC, and others) as well as those countries with the best road safety outcomes.
The approach highlights various key principles, including that:
→ People inevitably make mistakes that can lead to road crashes;
→ The human body has a limited physical ability to tolerate crash forces before serious harm occurs;
→ There is a responsibility on those who design, build, and manage roads and vehicles, as well as those who provide post-crash care to prevent crashes resulting in serious injury or death; and
→ All parts of the system must be strengthened to employ their effects so that if one part fails, road users are still protected.
Speed is a critical component within a Safe System. Safe speeds (see Q1.4) are needed to ensure when errors do occur, that they do not result in death or serious injury. The levels which speeds are considered safe depend upon the presence of vulnerable road users, vehicle types (and their protective features), and the protective nature of road and roadside infrastructure. Speeds at or below these levels will help eliminate death and serious injuries, which is the ultimate goal of the Safe System approach.
Learn more from the OECD/ITF Safe System guide here. To understand more about the origins of the Safe System approach, see a summary on Sustainable Safety from the Netherlands here, and on Vision Zero from Sweden here.
Speeding refers to road users travelling at speeds which are above the speed limit, also called as excessive speeds (which is dangerous and illegal), and also speeds that are inappropriate for road conditions (e.g. driving too fast during heavy rain or fog). Both of these have negative impacts on road safety outcomes and need to be addressed.
Sometimes a distinction is made between ‘high level’ or excessive speeding (often deliberate, and well above the speed limit) and ‘low level’ speeding (just above the speed limit, and sometimes unintentional). Both have an impact on safety outcomes (see Q8.4 for a discussion on how even small changes in speed can have a big safety impact).
The UN Global Road Safety Performance Targets indicate in target 6 the need that “by 2030, halve the proportion of vehicles travelling over the posted speed limit and achieve a reduction in speed related injuries and fatalities”.
Information on speed limits can be found in Q2.1 and Q2.2, while advice on better management of speeds can be found throughout these FAQs.
To be safe and appropriate, speeds need to reflect the type of road users that are likely to be part of the traffic mix, the protection offered by vehicles and road design, and be adapted to conditions, including weather.
When errors do occur (see Q1.2), the outcomes should not result in death or serious injury, and speed plays a critically important role in this. There are only certain forces that the human body can withstand during a crash, so speeds should be managed based on our understanding of this. Pedestrians can typically survive impacts speeds of around 30 kph, above which the chance of survival decreases dramatically. It is likely a similar impact speed applies for other unprotected road users such as motorcyclists and cyclists. At intersections, side impacts at or below 50 kph are survivable. For head-on crashes, road users in modern vehicles with good quality safety features can generally survive an impact at 70 kph with another vehicle of equal mass. To be safe, speeds need to be at or below these critical threshold levels.
If higher speeds are required, then better-quality infrastructure (including separation and crossing facilities for pedestrians; barrier protection systems to prevent head-on crashes etc.; see FAQs in section 3 for further examples) is usually required to support the increase in operating speed and protect road users.
Reaching safe speeds to eliminate death and serious injury should be the ultimate objective for road safety. However, where these speeds cannot be obtained in the short term, less substantial reductions in speed will also produce safety benefits (for information on this see Q1.9 and Q8.4).
Read more about Safe System speed limit setting here.
There are several reasons (excuses) why drivers speed and how they rationalize their speeding behavior. This potentially makes speeding behavior change a challenging, complex undertaking. According to robust Research, several factors contribute to speeding. Some of these factors are summarized in the table below:
A recent study characterized motivations and types of speeders using naturalistic driving data (Richard et al., 2012; see also Richard et al., 2013). Speeders were classified into four groups, based on the percentage of trips with speeding and the average amount of speeding per trip, namely:
incidental or infrequent speeders, meaning less trips with speeding and little speeding on these trips;
situational speeders, meaning less trips with speeding but a lot of speeding on these trips;
casual speeders, meaning many trips with speeding but only small amounts of speeding; and
habitual speeders, meaning speeding on most trips with a lot of speeding.
A 2020 survey by CarInsurance.com in the US reported that during the current COVID-19 pandemic many countries are reporting more traffic fatalities and handing out more speeding tickets. Fewer drivers on the road are leading motorists to take more risks, including speeding. About one-fifth of those surveyed explained they were late for work, didn’t see the sign, drove as fast as everyone else or had a medical emergency. Other excuses not quite as popular were they were headed for an interview, funeral, date and concert. For further information, see this link.
Additionally, the Transport Accident Commission in Victoria, Australia, in their Road Safety Monitor 2019, reported on drivers’ perceptions of speeds - see here.
About 650,000 people are estimated to die annually in road crashes because of speeding (for a definition of speeding see Q1.3), though this is most likely an under-estimate. Various studies indicate that speed is responsible for about 30%- to 50% of deaths on the road.
Although many studies indicate this level of contribution, many also qualify this to be an under-estimate, making speed an even higher proportion of road crashes. More significant is that reductions in speed can result in substantially greater levels of fatal and serious injury reduction (60%+).
The relationship between speeds and crash outcome has been captured in various models, most notably Nilsson’s “Power Model”. This shows that a 1% increase in average speed results in approximately a 2% increase in injury crash frequency, a 3% increase in severe crash frequency, and a 4% increase in fatal crash frequency (see Q1.7 to understand better the impact of speed). Thus, this model shows how decreasing speed by only a few km/h can significantly reduce the risks of and severity of crashes. Lower driving speeds also benefit quality of life, especially in urban areas as the reduction of speed mitigates air pollution, greenhouse gas emissions, fuel consumption and noise (see Q1.8 and Q1.9).
Learn more about this topic from WHO here; the European Commission here, ITF here, and the Pan American Health Organization here.
The higher the speed, the bigger and the more likely the mess. The operating speed of a vehicle impacts not only crash occurrence, but also the severity of a crash when it happens, through the driver’s field of vision and stopping distance (which covers the time to see and judge the need to stop – judgement time, moving to the brake and pressing it - reaction time, and actually stopping the vehicle - braking time), and also crash kinetic energy and losing vehicle control.
The faster a vehicle is moving, the more information the brain receives. However, the brain can only process a certain amount of information in any given time, which means that at 100 kph, it has to eliminate a large amount of peripheral information. This happens unconsciously. The field of vision therefore decreases as speed increases. See this gif showcasing how a driver’s peripheral vision at higher speeds.
In calculating the stopping distance, judgement and reaction time represent how long a driver takes to see both a hazard and the time it takes the brain to realize the danger and process a reaction to a hazard for example, starting to brake. This means that a vehicle travels further at higher speeds before they can react to a hazard. Although several studies have shown that a driver can react in as little as 1 second, most response times are between 1.5 and 4 seconds. The braking distance is the distance that a vehicle travels while slowing to a complete stop. As your speed increases - so does the distance you travel while your brain is processing information and reacting to it – and so does the distance you need to stop. So, the higher the speed, the higher the braking distance.
The kinetic energy of a moving vehicle is a function of its mass and velocity squared (E=1/2mv2) and this energy must be absorbed in a crash by friction, heat, and the damage suffered by the vehicle as a result of the crash. This means, the more kinetic energy to be absorbed in a crash, the greater the potential for injury to vehicle occupants and anyone hit by the vehicle.
Another way speed impacts road crashes and injury is by losing vehicle control: at higher speeds, cars become more difficult to maneuver - especially on corners or curves or where evasive action is necessary.
At the same time, higher speeds may also add risk for other road users. For example, a pedestrian may have selected a safe location to cross the road with sufficient site-distance to the crest of a hill or corner. However, a speeding driver may cover the distance from the position of not being visible to the crossing pedestrian much faster and thus hit the pedestrian.
The National Association of City Transport Officials (NACTO) presents the example below for an impactful communication of speed on fatalities from the city of Portland. Access the full document here.
Learn more about the impact of speed from studies in the Americas; Australia and Canada.
Speed not only affects road safety but also several environmental and health outcomes, such as:
→ Level of traffic noise: Road noise is the collective sound energy originating from motor vehicles as a result of friction between tire and the road surface, and also from the engine/transmission, aerodynamics, and braking elements. The noise of rolling tires driving on the pavement is found to be the biggest contributor to highway noise which increases with higher vehicle speeds. There is a link between traffic noise and health, with increases in noise leading to negative health outcomes.
→ Air pollution through the level of exhaust emissions: Speed has important impacts on air pollution as it is strongly related to the emissions of greenhouse gases (mainly CO2) and of local pollutants (CO, NOx, HC, particulates). While the process of emission generation is complex and varies within vehicles, across vehicle classifications and engine technologies, oxides of nitrogen (NOx) are produced particularly at high engine operating temperatures (e.g., steady high-speed driving) and a reduction in speed leads to a significant reduction in these emissions. Learn more on speed and environment from OECD (2006).
→ Fuel consumption: Speed also affects fuel consumption with most cars' fuel efficiency reaching a peak at speeds from 60 to 80 kph (equivalent to 35 to 50 miles per hour), but varies for vehicle type. In urban environments with regular slowing and stopping, the most fuel-efficient peak speed may be much lower. Fuel consumption is also linked to air pollution and greenhouse gas emissions. In a high-speed environment, i.e., in non-congested conditions, fuel consumption and CO2 emissions increase with increasing speed. However, at lower speed levels, reduced speeds do not necessarily lead to reduced fuel consumption. At speeds below 20 kph, fuel consumption increases significantly as well as air pollution.
→ Overall quality of life for people living or working near the road: As high-speed increases risk of road traffic crashes and injuries, but also air and noise pollution, there is no doubt that speed is linked with poor health and decreased quality of life. Unfortunately, it is a myth that speed means prosperity and progress when in reality, only a marginal benefit can mathematically be derived from increased travel speeds. For example, the extra travel time required for a 10 km journey will be less than 2 minutes if the travel speed is reduced from 50 kph to 45 kph (see Q8.7 and Q8.10 for more details on this myth). In stop/start traffic (which is typical in urban areas due to congestion and intersections) the increase in journey time is likely to be far less.
For more information, check out this study from the OECD (2006).
Road safety outcomes are usually measured in terms of the number of crashes and their severity levels, e.g., the total number of crashes; the number of fatalities and serious injuries. Speed plays a central role in all of these road safety outcomes.
There have been several research studies to quantify safety outcomes from speed changes. Much of this research comes from comparing outcomes before and after changes are made. This research is best summarized through Nilsson’s “power model” which shows that a 1% increase in average speed results in approximately a 2% increase in injury crash frequency, a 3% increase in severe crash frequency, and a 4% increase in fatal crash frequency. More recent research by Rune Elvik suggests that the relationship between collision risk and speed is exponential, and not a power law. The practical implication of this finding is that the rate of increase in crash risk varies with the initial speed level such that the effect of speed change is higher for high-speed roads than for lower speed roads. Also see here for an update.
Unsafe speeds and speeding are more harmful to pedestrians, cyclists, and motorcyclists (aptly called Vulnerable Road Users, VRU) than to vehicle occupants. Unsafe speeds are speed limits that are not set in alignment with the Safe System approach – read more about Safe System speed limit setting here and in Q1.4.
But why is this the case?
Firstly, the severity of injury depends on the forces to which our bodies are subjected. These in turn depend on the amount by which the speeds at which their bodies are travelling are changed within the very short duration of the impact. The changes in speed are determined by the physical laws of momentum and depend on the speeds at impact and the relative masses of the colliding vehicles, or of the vehicle crashing with a pedestrian or cyclist.
Pedestrians, cyclists, and motorcyclists do not have any or substantial protection against the raw forces of crashes such as crush zones, airbags, and seatbelts. In addition, mass differences are much more extreme in case of a crash between a vehicle and any of these vulnerable road users.
Therefore, a pedestrian, cyclist or motorcyclist is significantly more likely to die or sustain serious injuries at the same impact speed compared to vehicle occupants. For example, the risk of dying or sustaining serious injuries for a pedestrian greatly increases at any impact speed greater than 30 kph; this threshold is 70 kph for a head-on crash between two relatively similar cars. Read more here and in Q1.4.
Secondly, while grossly under-reported, speeding is a major contributing factor to pedestrian and cyclist crashes – read more about this here. It is shown that speeding is also a major contributing factor in motorcycle crashes – over 50% of motorcyclist fatal crashes are reported to be caused by speeding (find more about this here).
Therefore, pedestrians, cyclists and motorcyclists are more likely to suffer from the consequences of unsafe speed and speeding. The International Transport Forum’s report, ‘Speed and crash risk,’ provides more information on this.
It should be noted that even amongst VRUs some groups are more vulnerable such as children, the elderly, and persons with disability to name a few. This is because of potentially more vulnerable physiques, less developed or deteriorating cognitive capacities, and the higher likelihood of relying on walking, cycling or motorcycling as the main mode of transport (See FAQ 2.7).
Overwhelmingly, speed is the top contributing factor in road crash fatalities and serious injuries. Speed not only affects the driver, it can also have an impact on the vehicle occupants, pedestrians, cyclists, motorcyclists or other road users. Hence, a sound speed management approach is essential in reducing and preventing road fatalities and injuries.
Thus, the first step in speed management is identifying the speed issue. Note that the issue may be excess speeds (drivers exceeding the posted speed limit) or inappropriate speeds (driving faster than the prevailing road or weather conditions allow) or a speed limit that is too high for safety (see Q1.4 to learn about safe and appropriate speeds). Site reviews including the evaluation of crash data, speed measurements, as well as input from the local traffic police, road authority and communities can be used to confirm if excessive speed is present, to what extent and the reason why. Once the specific issue is identified, specific mitigating measures need to be identified along with the change in speed limit if needed. These measures could be in the form of infrastructure improvement or enforcement.
Learn more on the basics of speed management from WHO and the European Commission.
Speed management involves various techniques to reduce/modify the speed of road users, usually motorized vehicles. The purpose is to ensure that speeds are safe for all road users to avoid injuries and death. Other benefits can include improved traffic flow, reduced noise and air pollution, and reduced climate change impacts of road transport.
The management of speed can be achieved through the use of appropriate speed limits, provision of road infrastructure to support these limits, police enforcement, education and community engagement, and vehicle technologies. A mixture of these approaches is often used and considered as the most effective (also see Q1.1).
Speed Enforcement is an important and necessary measure for speed management. In many countries speed enforcement has significantly evolved over the past decade with a general increase in the focus of enforcement efforts and the increasingly widespread introduction of automated speed control, which does give a new dimension to the enforcement effort. If undertaken appropriately, speed enforcement can be a very powerful measure (deterrent) that contributes directly to reducing the incidence of speeding and consequently, the frequency and severity of collisions (see Q4.2).
As with all road safety interventions, they should not be implemented in isolation from other key activities. Speed enforcement should be an integrated component of an overall Speed Management Strategy. This is particularly important as speed limits are introduced or changed.
For more information see here.
A speed management strategy (also called a speed management program) is a long-term document that describes an efficient framework for implementing safe speeds for the whole road network in a country. It is based on the Safe System approach and covers the focus areas as well as goals and objectives of speed management. A speed management strategy is usually set at national level in line with the national road safety program, agreed on at high political level and issued by the responsible Department/Ministry.
To succeed, many different organizations, e.g., Ministry of Transport (Road Safety Agency), Ministry of Public Works (Road Authority), Ministry of the Interior (Police), Ministry of Health (Emergency Services), Road Safety Organizations including civil society, are required to be involved in developing the strategy and supporting its implementation.
The speed management action plan defines the concrete actions including timelines to be implemented, e.g., in the fields of engineering, enforcement or public campaigns, with the aim of managing speed and reducing speed related fatalities and serious injury crashes. It is usually issued by the responsible road operator e.g., by a local administration (such as a region, province or city) or a public or private entity (such as a motorway operator/concessionnaire or a large company). The action plan should be based on the national speed management strategy and delineates specific activities to be pursued and steps for their implementation, such as a change in local speed limits for designated roads or the implementation of concrete speed management solutions where speeding is a problem. Furthermore, the action plan includes information for engineers, enforcement agencies and other partner organizations to identify and treat high-risk locations.
Learn more about this topic here and see an Action Plan example here.
A speed management strategy is a coordinated approach based on the Safe System principles to addressing inappropriate speeds and providing a framework for how to create safety and mobility for all road users considering the specific road conditions across a road network (also see Q1.13).
To be successful, a speed management strategy requires a thorough investigation of all the factors affecting speed, such as general driver behavior, road design, land usage, and current legal speed limits, and should cover the following main aspects:
Analyzing the current speed management setup and existing challenges;
Evaluating the legal and organizational context;
Reviewing and improving (where necessary) crash and speed data collection and analysis;
Gaining political support for better speed management and enhanced communication on the relationship between speed, speeding, and safety;
Seeking the cooperation of national key stakeholders;
Defining research needs to increase understanding and knowledge of speeding and resulting crashes;
Creating/updating the legal framework for speed management and defining general speed limits that are safe and reasonable;
Considering speed-related issues in land use planning;
Creating an organizational setup for implementing and improving road design standards for different road and intersection types, that assure safety at the set speed limit;
Defining enforcement efforts and appropriate technology that effectively address speeders and deter speeding;
Promoting vehicle technologies that reduce speeding, such as Intelligent Speed Adaptation (ISA) (see FAQ6.9 and 6.10);
Creating awareness through targeted marketing, communication, and educational messages that focus on high-risk drivers.
For an example of a speed management plan from the US, please see here. For can example from Bogota, Colombia (in Spanish) see here.
Managing speed can not only save high numbers of lives with relatively low investments, but provides an opportunity to improve climate change, health, inclusion, the economy and congestion.
In this context, road design and engineering interventions are often most cost-effective and powerful, especially in cities, towns and villages with low or moderate speed environments. These interventions include road lane narrowing though reducing the width of the travel lanes, raised platform crossings, speed humps, gateway treatments as well as well-designed roundabouts. All are proven to be effective and are typically more sustainable than pure reliance on – often isolated – speed enforcement or education activities. As an example, a recent World Bank study identified that for every $1 invested in traffic calming techniques, benefits of $17 could be expected (see here).
Lowering speed limits at hazardous locations as well as automated speed enforcement (speed cameras) prove to be very cost-effective, especially when combined with road engineering measures. Benefits of more than $14 for every $1 invested could be expected from these measures (see here).
Finally, also vehicle technology provides cost-effective speed management solutions, such as Intelligent Speed Adaptation (ISA) or speed limiters for heavy vehicles, which have proven road safety benefits, as well as positive effects on fuel consumption and emissions. For example, benefits of more than $8 could be expected from every $1 invested in ISA (see here).
If you want to know more about cost-effective speed management solutions, see here.
Powered two-wheelers (PTWs) comprise a significant part of the national vehicle fleet in many low- and middle-income countries (+70% in some) and, globally, the majority of PTW-related deaths (90%) occur in low- and middle-income countries. According to WHO’s Global Status Report on road safety 2018, in South-East Asia, 43% of all road deaths are among riders of motorized two- and three-wheelers, while in the Western Pacific region the figure is 36%. In other regions, the figure is between 9% and 23% of all deaths. Find the WHO report here.
According to “Motorcycle Safety,” a Fact Sheet from the Centre for Accident Research & Road Safety - Queensland (CARRS-Q), fatality and serious injury rates are 30 and 41 times greater, respectively, for motorcyclists than car occupants. There are several factors that contribute to the over-representation of motorcyclists in fatal and serious-injury crashes, namely:
Being more exposed to crash forces given their limited physical protection
PTWs’ operation mechanism and limited contact with road surface, and their susceptibility to road surface, road, and environmental hazards
Instability, braking difficulties and other vehicle safety issues
Human factor and road user behaviour issues such as inexperience or lack of recent experience, drivers’ failure to see PTWs and risk taking and aberrant behaviour such as excessive speed.
Specifically, excessive speed is a major factor in motorcyclist crashes. The U.S. Department of Transport’s ‘Traffic Safety Facts – Motorcycles’ points out that 33% of all motorcycle riders involved in fatal crashes in 2017 were speeding, compared to 18 percent for passenger car drivers, 14 percent for light-truck drivers, and 7 percent for large-truck drivers. Find the report here.
Similarly, a recent review of international literature on the impact of speeding on motorcycle safety shows that speeding was reported as a contributing factor in at least a third of all fatal motorcycle crashes – find the review here.
In Thailand, where motorcyclist deaths account for almost three-quarters of all road fatalities, a recent study suggests that speeding motorcyclists are 63% more likely to be involved in casualty crashes compared to those who abide by the speed limit. Find the study here.
A study of motorcycle crashes resulting in hospitalisation in Ho Chi Minh City, Vietnam, shows that at least 26% of motorcyclists were speeding at the time of the crash. Details of the study can be found here.
It is often stated that motorcyclists travel faster than other types of motorized vehicles, and there is good evidence to support this. For example, in 2014, the Belgian Road Safety Institute (BRSI) conducted motorcyclist speed measurement at over 300 locations from around Belgium to: a) obtain a representative and objective measure of the speed driven by motorcyclists in Belgium; and b) compare their speed with that of car drivers and with the actual speed limits.
The main findings of this study confirm that, in general, motorcyclists ride faster and commit more speed infringements than car drivers. Find the survey results here. More specifically:
On 30 kph roads, two-thirds of the motorcyclists exceeded the speed limit by more than 10 kph.
On 50 kph roads inside built-up areas, the average measured free speed of motorbikes was approximately 3 kph higher than the average free speed of cars, and 5 kph above the speed limit.
Outside built-up areas, the average free speed of motorcyclists was significantly higher than that of car drivers: a) 5 kph on 70 kph roads; b) 7 kph on single lane 90 kph roads; c) 4 kph on double lane 90 kph roads
On 120 kph highways, the average free speed of motorcyclists was 121 kph.
Furthermore, monitoring motorcyclists’ attitudes towards speeding indicates that many riders believe there should be leeway to allow for travel above the posted speed limit, especially for high-speed roads. The Motorcycle Monitor – the Transport Accident Commission (TAC), Australia – provides an example. Find it here.
A comprehensive study of motorcyclists’ speed behaviour in Malaysia shows that motorcyclists go faster than drivers on primary and collector roads. Specifically, on lower-hierarchy roads, i.e., collector roads, motorcyclists travel almost 20% faster than drivers. Drivers on the other hand travel at higher speeds than motorcyclists on expressways (16%) and secondary roads (10%). Find the report here on the website of the Malaysian Institute of Road Safety Research (MIROS).
2. Policies and strategies for speed management
According to the WHO Global Status Report on Road Safety 2018, only 46 countries representing 3 billion people currently have laws setting speed limits that align with best practice. This number has not changed since 2014, and an interactive map with speed limits worldwide can be viewed here.
Globally, there are mainly three different types of speed limits:
1. Default speed limits as specified in relevant legislation (e.g. Road Code), which set the general maximum speed allowed on specific types of roads such as motorways or urban roads; no additional signposting is needed to enforce these limits.
2. Signposted maximum speed limits on roads or sections of roads.
3. Speed limits for specific vehicle or road user types – e.g. farm vehicles, heavy transport vehicles or novice drivers.
It needs to be noted that the default speed limit as well as the posted speed limit indicate the maximum allowable speed for a certain road or stretch of road and not the recommended or appropriate speed at a specific location.
It is also possible to set variable speed limits (VSL). These are flexible restrictions on a certain stretch of road. The speed limit changes according to the current road, traffic, weather or environmental conditions and is displayed on an (electronic) variable message sign (VMS) or on static signs. A VSL may also be used in school zones to provide a safer road environment, to reinforce driver expectations of the likely presence of children and to encourage safe and active travel to school.
Finally, there are also so-called differential speed limits (DSL) with different speed limits for different types of vehicles on the same type of road, e.g. for cars and trucks on motorways.
You want to know more? Click here.
Determining the ‘right’, compliant speed limit from a Safe System perspective (see Q1.2) for your road is a very complex task depending on the local factors at hand. Still, you might base your decisions for setting speed limits on the following four principles:
a. Road safety principle
→ Set speed limits to minimize the risk of death or serious injury to all road users where vehicle speeds would result in impact forces exceeding tolerance of the human body.
→ Set speed limits to minimize the risk of death or serious injury to all road users when there is an increased risk of crashes due to a change in operational and/or environmental conditions.
b. Community wellbeing principle
→ Set speed limits, especially on local roads, at a level that supports active transport modes (walking, cycling) and minimizes impacts on amenity.
→ Set speed limits by consulting the affected communities and road users so that expectations, where possible, are considered and impacts of speed changes are understood by the public.
c. Road network efficiency principle
→ Set speed limits in accordance with the functional road class and the standard of the infrastructure.
→ Set speed limits to achieve operating speeds that support an efficient network wide outcome and do not just focus on one isolated section of road.
→ Set speed limits to minimize the overall delay to road users where there is a change in operational conditions (e.g. by variable speed limits, see Q2.1).
d. Road user expectation principle
→ Set speed limits to be consistent with speed limits on roads in a similar environment with similar characteristics and function.
→ Set speed limits so they are clear and easily understood and keep the number of speed limit changes to a minimum.
Among these four, the road safety principle is the most important and should therefore be given priority whenever one principle has to be weighed against another in the decision-making process.
Policy on the minimum length of speed limits is also vital. Speed limits should not change regularly over a few hundred meters, for example. Too many limit changes create confusion and frustration for drivers. Thus, it may be appropriate to set a minimum length for each speed limit. For each section the posted speed limit should be determined as the lowest safe speed for any location within that length.
Learn more about this from Australia here and from Europe here.
Spot speed measurements are your way forward. These measurements can be used to assess free flow speeds on a representative sample of urban and rural roads as an important basis for setting up a speed management strategy.
The spot speed is defined as the instantaneous speed of a vehicle at a certain point or a specified location. In road safety work spot speeds are for example used as basic input data for crash analysis, but are also required for road design (e.g., horizontal and vertical curves, super elevation) and to determine the location and size of signs and the design of signals.
There are different techniques to measure spot speeds. The most common devices use either radar (radar meters) or laser sensors (speed lasers), which may be hand-held (so-called ‘speed guns’), mounted in a vehicle or on a tripod. Radar and laser devices require line-of-sight to accurately measure speed and are easily operated by one person. If traffic is heavy or the sampling strategy is complex, two units may be needed.
Besides using radar or laser technology, spot speeds may be estimated manually by measuring the time it takes a vehicle to travel between two defined points on the road, which are a known short distance (e.g., 1 m) apart. This technique is often called stopwatch method. The measurements are very simple and can be conducted by either two observers or by using an enoscope (mirror box) and only one observer. Manual measurements are only applicable for very low traffic volumes and a small sample size taken over a relatively short period of time.
For longer data collection periods pressure contact tubes (pneumatic or electric) can be used. Two contact tubes are placed in the travel lanes of the road and the time is measured between the electric impulse generated when a vehicle runs over the first and then the second tube. The advantages of this method include the ability to collect and store data on 100% of vehicles, and capacity to continuously record for many hours and days. In addition, there is no risk of driver behavior being influenced by seeing a person ahead with a ‘speed gun.’
The most advanced (and expensive) technologies use traffic monitoring cameras and software algorithms to determine speeds from real-time traffic data. An ever-emerging research field is real-time traffic monitoring using mobile phone data or GPS data and estimating traffic speeds using these data sources. Due to the high market penetration of mobile phones not only in HICs but also in LMICs, very detailed spatial data at lower costs than with traditional data collection techniques would be available. Data from cellular phones open new and important developments in transportation engineering but several steps are still needed to achieve a significant confidence in the use of these data, not only in terms of data reliability but also regarding privacy and security issues.
Click here or here to get more details on methods for measuring traffic speeds.
Regardless of the speed measurement method used, you might keep in mind that speed survey results highly depend on the way the survey is conducted. Therefore, you might follow these steps:
1. Select appropriate location for the specific purpose of the study considering that the location is safe for the operator and away from specific features that might influence speeds.
2. Select appropriate speed measuring device (e.g., contact tubes) for the specific purpose of the study.
3. Choose sample size considering the different types of vehicles using the roads (motorcycles, cars, lorries), the traffic volume and variables such as time of day, day of week, holidays and weather conditions (e.g., 200 vehicles of each type over a minimum of 2 hours).
4. When measuring free flow speeds select those vehicles that have a substantial headway and are not impeded by other vehicles or other factors (minimum headway of 3-4 seconds is recommended). Note that for some purposes, collection of speeds from all vehicles (i.e., not including a minimum headway) may be desirable.
5. Guarantee minimum influence of the observer and/or equipment on the drivers and their speed (hide observer and recording equipment, if possible).
6. Collect and evaluate the data (minimum evaluation should include average speed and 85th percentile speed).
It is a good idea to repeat speed surveys on a regular basis to show trends in vehicle speeds and monitor impact of speed management on driver behavior. In that case keep in mind the following:
→ Conduct the speed surveys under similar conditions each time, as any variation in collection procedures may result in differences in the speeds recorded.
→ Use the same location as well as the same recording equipment, and preferably the same equipment operator.
You can learn more here from a New Zealand case study, or here from Austroad’s Transport Studies and Analysis Methods. A very useful document for you might also be the Overseas Road Note 11 ‘Urban Road Traffic Surveys’.
The free-flow speed is a drivers' desired speed on a road at low traffic volume and absence of traffic control devices. In other words, it is the average speed that a motorist would travel if there was no congestion or other adverse conditions (such as bad weather).
When measuring free flow speeds (see Q2.3) select those vehicles that have a substantial headway and are not impeded by other vehicles or other factors (minimum headway of 3-4 seconds is recommended).
Free flow speeds and 85th percentile speeds are NOT a good guide for selecting speed limits (see Q2.6).
The 85th percentile speed is the speed at which 85% of free-flowing vehicles (see Q2.5) are traveling at or below. For example, this speed can be determined by conducting and evaluating a spot speed study (see Q2.3).
The 85th percentile speed is often used by traffic engineers as the basis for road design. In many countries it is still used as primary tool for setting speed limits (Q2.2), and (more controversially) as a reason against lowering or enforcing limits. In this context, the following three misleading arguments for using 85th percentiles for setting speed limits are put forward:
2. The speed dispersion argument, i.e. speed limits near the 85th percentile will minimize the variance of the speed distribution, thereby minimizing opportunities for vehicle conflict and crashes.
3. The enforcement practicality argument, i.e. 85th percentile limits represent a reasonable and realistic benchmark for enforcement.
But none of these arguments are valid. The majority of drivers will not always make well-balanced decisions and select speeds that are safe. Speed choice will often be biased towards personal benefit (e.g. reduction in perceived travel times) as opposed to collective risk (e.g. overall crash risks). Also, drivers’ subjective assessments of risk, and the relationship between speed and risk, are likely to be inaccurate. As far as speed dispersion is concerned many studies showed that the majority of fatal crashes are crashes where speed dispersion is an unlikely factor (e.g. single vehicle crashes, intersection crashes, pedestrian crashes). Finally, nowadays there is strong evidence that setting and enforcing lower speed limits than the 85th percentile speed is feasible, sustainable, and produces safety benefits.
Therefore, countries that have already adopted the safe system approach have discontinued the use of 85th percentiles for speed limit setting. For these countries avoiding death and injury is an absolute priority, and the speed management system as a whole must be based on this philosophy and on an objective assessment of risks.
One short side note: The 85th percentile is an excellent way of demonstrating when speed limits and road design don’t match, and the design of a road is inappropriate for the posted speed limit. Here is an example:
On an inner-urban residential road the speed limit was lowered from 50 kph to 30 kph, without any changes to the road design for the motorized vehicles. The 85th percentile speed of motorized vehicles on this street is measured after the introduction of the lower limit and is found to be still close to 50 kph. This tells you that the road design isn’t doing its job. In the short term you could get the police out with speed guns, but in the long-term the design of the road and its environment should be changed by clever inner-urban road safety engineering solutions (see Question 3.2), which will reduce the 85th percentile speed.
You can learn more here from an ITF report, or here from a guide from Australia.
Vulnerable road users such as pedestrians, cyclists or powered two-wheelers have a high risk of severe or fatal injury when they are hit by motor vehicles. This is because they are often physically completely unprotected or only have very limited protection, compared with the safety of a vehicle with a rigid safety shell and airbags.
The probability that a vulnerable road user will be killed if hit by a motor vehicle increases drastically with speed. If hit by a car at 30 kph, 10% of vulnerable road users die, another 15% are seriously injured and 75% are slightly injured. If the impact speed increases to 50 kph these numbers change dramatically: 80% die, 3% are seriously and 17% slightly injured.
The situation is even worse for elderly pedestrians. In fact, pedestrians over the age of 75 are twice as likely to be killed in a crash as those under 34. Elderly people are much more susceptible to injury if they are struck by a vehicle. Their bones are much frailer, and their overall state of health is worse – factors that can make even a minor crash turn lethal. Elderly pedestrians are also more vulnerable to being involved in a crash because of age-related declines in cognitive function and vision.
Children are also highly vulnerable to injuries from motor vehicle impacts. This vulnerability occurs for several reasons including that they have less developed cognitive and perceptual skills and so are less able to make decisions about safe behavior around traffic; the decisions they do make may be less predictable to other road users (such as running after a ball); they are smaller than adults, and so may be harder to see or be seen in traffic; and there is emerging evidence that they are more likely to suffer more severe injuries when struck as pedestrians (especially head injuries).
Under the Safe System approach (see Q1.2) the setting of speed limits considers the risks to road users of sustaining fatal or serious injuries. For example, at locations where there is a significant level of pedestrian or cyclist activity, lower speed limits are appropriate. Similarly, where the potential for conflicts is high (e.g., on busy urban roads with frequent points of access) speed limits are to be set at a level that will minimize the chances of fatal or serious injuries in the event of a crash.
You can learn more on this topic from WHO here, Vision Zero here or Australia here.
Motorcyclists are becoming an ever more important component of the transport system. Increasing numbers of people not only in low- and middle-income but also in high-income countries are choosing to ride motorcycles.
This is potentially because of: a) the lower cost of purchasing motorcycles, b) increasing congestions, reduced parking availability, and increasing travel costs, and c) versatility and convenience of riding motorcycles. In some countries (especially high-income countries) there is also a growing interest in riding motorcycles among older and often returning riders, and this can be based on the reasons above, as well as interest in recreational riding.
The International Transport Forum (ITF) points out specific policies and strategies that directly influence a Safe System compliant choice of speed and motorcyclist speeding management policies, namely:
→ Conduct in-depth and naturalistic studies to better understand the role of speed and speeding in motorcyclist fatal and serious injuries.
→ Include motorcyclist safety and mobility in national transport policy including safety, green transport, livability, and sustainability.
→ Develop a policy of modal priority for road users, particularly in urban environments, based on vulnerability and sustainability goals.
→ Develop mandatory manufacturing rules and regulations to adopt motorcycle safety features such as motorcycle Anti-lock Braking System (ABS), Combined Braking Systems (CBS), stability control, and Automatic Emergency Call Systems. See also question 6.1.
→ Address the current difficulties in enforcing motorcyclist compliance with speed limits, and develop complementary education/enforcement policies and programs to address the motorcyclist excessive speed issue.
→ Develop enhanced enforcement programs with a focus on identified motorcyclist crash risk locations and popular motorcycling routes.
→ Consider zero-tolerance for motorcyclist speed enforcement or a minimal leeway.
Find the ITF reference here.
Legal requirements regarding the responsibility for setting of speed limits vary between countries. Regardless of these requirements it is important to involve key stakeholders in the speed limit setting process.
Speed limits should be set based on multiple principles (see Q2.2) to provide safe and efficient travel between destinations. The acceptability of new speed limits will depend on the support from politicians and decision-makers, as well as from the (local) community itself.
Once evidence is produced that speed and speeding are problematic, support from local stakeholders for lowering the speed limit must be obtained and the affected communities and road users should be consulted so that impacts of speed changes are understood by the public and expectations can be managed.
It is also important to involve road engineers, traffic police (noting that these two groups are often legally responsible for instigating speed limit changes), emergency services, and – where necessary – public transport providers as well as communication experts in an early stage to define the most cost-effective and feasible measures in engineering, enforcement and creating support to accompany the new speed limit.
Learn more about this from the WHO speed management manual here. You can also find more about stakeholder and community engagement in Section 4 of Victoria’s Speed Zoning Guidelines.
The correct political environment is an essential requirement in road safety, including speed enforcement, if it is to become a government priority for action including funding. Government support for any public policy issue is always subject to constraints including the time and resource constraints necessary for policy development and subsequent legislation.
Political support needs to be expressed in a long-term vision that addresses the greater public good, and to ensure adequate funding is earmarked to implement required initiatives in addition to new legislative and regulatory initiatives. In many cases, speed management is seen to be in direct conflict with other priorities, such as reduced congestion and shorter journey times (which are actually myths – see 8.2 and 8.10), or public spending in other areas. Government priorities can be changed to align better with road safety.
In presenting an enforcement plan to government (at any level) there will be greater success if you include these components:
Present a solid business case – clearly identifying the costs and (significant) benefits (from injury and death reductions); resources required, both human and financial; and, a detailed implementation plan, including a robust monitoring and evaluation component. It is helpful if the economic savings of improved safety are highlighted, so that there is a clear overall economic gain showing that road safety is not just a social good, but a sound economic investment.
Community support – this should include all aspects of the community, particularly representatives from victim advocacy groups.
Transparency - to avoid criticism from opposition that views this type of enforcement as a “revenue generator”.
Demonstrate Leadership – Governments can be seen as true supporters of the importance of road safety, and specifically speed management. Road safety should be a non-political issue, therefore all parties should support the program to ensure that the program survives government elections.
Governments may also see risks in certain road safety policies, often based on poor or biased data (such as some claims about community views in the media). Appreciation of these government perceptions and opportunities to manage them can change political decision making. For example, media may present speed management as unpopular based on the vocal minority. In such cases, sound community surveys of attitudes and beliefs can show common support for better speed management.
You can find out how the French automated speed enforcement system was launched in November 2003 from a OECD study (Box 5.2), and also from the Global Alliance for NGOs for Road Safety resources on Political Commitment. The Commonwealth Road Safety Initiative (CRSI) and Governors Highway Safety Association (GHSA) also provide good examples. Information from international surveys on road user attitudes relating to speed can be found here.
Road safety is not only influenced by the average speed on a road, but also differences between the speed (also called speed variance) of the various modes of transport sharing the road. Roads with a large speed variance are considered less safe than roads with a small variance. This is not only valid for roads with motorized traffic but also for stretches of roads that slower pedestrians (such as the elderly or those with disabilities) must share with much faster cyclists or mobility scooters.
One of the added advantages of lower speed limits and managing speeds down is that this reduces differences in speeds between the inevitably slower users and others.
A large variability and big differences in the speeds of various road users in the same road space cause disturbances in the traffic flow and increase the risk of crash occurrence and severity. This might be the case, for example, if a straight and high-speed road section is followed by a narrower section with a lower speed, without adequate advance information for the road users. In such circumstances, consistency between road design and speed management is extremely important to provide road users with a predictable road environment encouraging safer driver behavior.
When it is not possible to segregate slow-speed traffic from high-speed road environment, lowering the speed of the facility may be the best option.
Network and town planning practices need to reflect the needs of vulnerable road users and enable the adoption of Safe System speeds. Three of the more relevant examples are discussed here, namely: A) the Dutch functional network structure, B) the Spanish superblocks, and C) 20-minute neighborhoods.
Since the late 1990s, the Netherlands has incorporated sustainable safety into the categorization and layout of its road network and town planning – this is called, functional network structure. Based on two main functions of roads and streets, namely: flow and access, three road categories are distinguished in the Netherlands:
- → Through roads allow traffic to travel from origin to destination as quickly and safely as possible ('flow'). Through roads may only be situated outside urban areas.
- → Access roads offer direct access to residential areas at locations of origin and destination.
- → Distributor roads connect the through roads with the access roads. Distributor roads are found in both urban and rural areas.
Most relevant to vulnerable road users, ‘access roads’, provide access to homes, businesses, schools, hospitals, shops, etc. Access roads can be mainly found in areas with a residential function. This means that all types of traffic mix here: pedestrians, cyclists, motorcycles, cars, and trucks.
In urban areas, access roads have a 30 kph speed limit. In addition to 30 kph access roads there are home-zones. Home-zones have a 15 kph speed limit and pedestrians can walk and play on the entire width of the street.
The adoption of functional network structure has had a large impact on road safety in the Netherlands. Read more about it here.
Superblocks are neighborhoods of several blocks (e.g. 9 blocks in Barcelona) where through traffic is, completely or partially, banned. They are accessible to local and access traffic, and community and emergency services. However, speed limits are lowered to between 10 and 30 kph.
A new town planning paradigm, superblocks are shown to prevent premature deaths, improve air quality, promote physical activity and prevent public health issues, e.g., road trauma.
Superblocks are also effective planning measures to manage speed and improve vulnerable road user safety. By dropping speed limits to levels that are compliant with the Safe System approach, Superblocks allow people of various ages and capabilities to adopt an active lifestyle. Compared to a default speed limit of 50 kph, a superblock with a speed limit of 20 kph can be almost 90% safer for pedestrians and cyclists.
More specifically, assessing a superblock through the Kinetic Energy Management Model (KEMM) lens, we see that superblocks fulfil three important traffic safety functions: a) they reduce people's exposure to cars, b) they create an environment that is easier to navigate and understand, and where the intrinsic risk of crashes is lower, and c) any potential collision is likely to occur at lower speeds and not be severely injurious to pedestrians and cyclists. Read more about superblocks here and here.
A successful planning approach, the 20-minute neighborhood emphasizes the value of living locally and providing people with active transport options to meet as many daily needs as possible within a 20-minute walk from home, with safe cycling and walking facilities and local transport options. Embedded in strategic urban planning of many cities, the 20-minute neighborhood is a promising tool to deliver healthy and environmentally friendly environments while ensuring safety and speed management measures as well. Specifically, it helps us manage exposure to traffic risk for some of the most vulnerable community groups such as children, persons with disabilities, women and the elderly, and creates justification to reduce speed and provide better walking/cycling facilities. Find Melbourne’s plan for its 20-minute neighborhoods here, the Paris example here (a 15-minute city) and information from Bogota here.
The levels of Vulnerable Road Users (VRU) road trauma greatly increase when the posted speed is beyond the threshold advised by the Safe System approach – read more about these thresholds here and in Q1.4.
It is known that the human body is vulnerable and not ‘built’ to withstand impact forces greater than around 30 kph – any speed greater than this greatly increases the risk of dying or sustaining serious injuries. This risk is even greater for some of the VRU groups such as children, the elderly and people with disabilities. For an interesting exploration on how to ‘build’ a body to better withstand higher crash speeds, meet Graham here.
The relationship between VRU road trauma and posted speed limit is shown to be a positive correlation – in other words, when the speed limit is reduced, VRU road trauma is shown to decrease, and vice versa.
Considering that 30 kph is the Safe System compliant speed for pedestrian and cyclist safety, several jurisdictions have set widespread 30 kph zones across their dense urban areas. The City of Oslo (Norway), for example, achieved Zero pedestrian and cyclist fatalities by implementing a series of interventions. Since 2015, Oslo has implemented a series of traffic calming measures including around 500 speed humps and has lowered speed limits systematically so that almost two-thirds of the city’s network now has a speed limit of 30 kph. The city government is determined to make 30 kph the standard citywide speed limit in the future. Other cities around the world (for example Paris and cities in Spain) have now followed this 30 kph example.
It is also shown that if on a particular road the average speed increases, then the number of crashes will increase, with serious crashes increasing to a larger extent than less serious crashes. While this is a general rule, we can safely assume that this is the case for VRU road trauma as well. Read more about the relationship between speed and road trauma here.
The Road Safety Country Profiles guide points out that Safe speeds are a critical component of the Safe System approach offering powerful, inexpensive opportunities to save lives and debilitating injuries, especially for VRUs. However, the report points out that none of the Low-Income Countries (LICs) and only 3% of Middle-Income Countries (MICs) have adopted speed limits <= 30kph in their urban areas.
It should be noted that setting Safe System compliant speeds for VRUs safety purposes has significant safety benefits for vehicle occupant safety as well. As can be seen in Q1.4, speed limits less than or equal to 30 kph are well within the safety tolerance of vehicle occupants.
The use of social marketing or publicity is an effective way to support enforcement operations and effectiveness. It is very important that road users are aware of the increased levels of enforcement activity through these communications strategies, and that they understand the reason behind it, otherwise behavioral changes are usually only short term.
Research has identified that the impacts of advertising and publicity alone have limited impact on changing driver behavior, and to be successful they do need to be accompanied by relevant and timely enforcement. Publicity as a stand-alone measure could increase community awareness of traffic safety issues, however, it has only a minimal effect on actual road user behavior and injury prevention.
The communication strategy should be focused on specific target groups (ages and demographics) and also related to specific locations and actions/objectives, such as inappropriate speeding occurrences, therefore aiming to reduce these incidents.
Objectives for public communications about speed management include:
Providing information to drivers and other road users about speed management actions and the change in behavior expected from them.
Motivating drivers to comply with speed limits and safe speeds.
Encouraging and motivating public support for actions addressing the speeding problem.
Print or broadcast media and other means of communications may be used to increase deterrence and voluntary compliance. Educating the driving public on the basis for speed limits and the community’s speed enforcement policy may also work to reduce speeds. While these types of media have been around for several years, more recently online social media campaigns appear to provide greater opportunities for the public to better engage and interact, not only exchanging/sharing information but also in changing the culture (social norms / social acceptance) around speeding. Social media is most important in reaching a younger audience. It is important (and valuable) to use social media as a way to engage people in the campaign, rather than as a one-way communications channel. For example, you can encourage followers and partners to share, re-tweet and like your campaign messages and visual content like photos, infographics, and film clips, and to promote the campaign to a wider audience. You can also invite people to give their views on the campaign topic and feedback on how the event went and post their own pictures and film clips. See also information in Q7.2 and Q7.5.
For detailed information on this topic, see the WHO ‘Road safety mass media campaigns toolkit’ here. Click here to learn about a GRSP award-winning speed campaign; another good example from BRAKE here; and a research study here.
Road safety and speed management have long been recognized to be political issues. There are several cultural, social, and psychological factors that can lead to resistance to speed change. Often these are perceived barriers, but even this perception can reduce the appetite for changes in speed by decision makers. The most important action to counter this resistance would be to genuinely adopt a Safe System approach, increasing the focus of road safety resources on providing a system which forgives human error rather than imagining road users will ever be perfect.
Support must be actively sought – often over a longer period of time. In this context the following steps might be helpful:
Provide politicians in key ministries and their direct staff with state-of-the-art scientific facts and figures that speed and speeding are a major road safety (and public health) issues creating a significant economic burden;
Provide politicians with individual accounts of the impacts speed crashes had on the lives of their constituents;
Show that there are countermeasures that actually worked in other countries with similar contexts as their own countries (before-after-studies);
Present the possibility of pilot projects or tactical urbanism to try out countermeasures on a small scale or as a phased approach to instigating speed change;
When implementing countermeasures start with high-risk locations first (e.g., near schools, or at areas where many vulnerable road users are present) where the risk can be more easily be recognized by the community and decision makers, and the impacts will be greatest;
Conduct surveys to determine the public response to crash risk, speeding and the possible countermeasures;
Team up with senior government officials within key ministries and stakeholders who are in direct contact with the political level to support speed management activities;
Work with media representatives (including provision of training) to provide evidence-based information on the need for change, and the effectiveness of speed-related interventions;
Brief politicians in key ministries and their direct staff regularly on positive effects and successes of the speed management strategy.
One widely quoted example of strong political support leading to firm speed-related road safety outcomes comes from France. In his presidential address in July 2002, then French President, Jacques Chirac, announced that road safety had to become a national priority. This led directly to the launch of the French automated speed enforcement system in November 2003. Based on this and other measures, the number of road deaths fell by up to 40 percent in France between 2002 and 2007. Further details of this case study can be found here.
When a violation has been detected, it must be followed by an appropriate and effective sanction/penalty. These penalties must be certain, unavoidable and equitable for all offenders. When coupled with other legislative and regulatory changes, penalties can support the goals of the overall speed management program, which are saving lives and preventing serious injuries. Sanctions are a key component of any enforcement program and without exception, if an offence is detected it will be followed by a sanction. In fact, a study by Mäkinen et al., 2003, concluded that “the certainty of a sanction appears to be more important than the severity of the sanction, particularly if the chance of apprehension is small”.
Sanctions can take the form of fines, demerit points, or driving licence suspension and vehicle impoundment. Often, a variety of penalties can be combined to increase the effect of deterrence. All penalties must be used in line with the governing legislative authority.
Penalties also play a role in educating drivers in heightening the level of risk that is involved with various offences. Delivering more severe penalties for more dangerous driving behaviours emphasizes the consequence of those behaviours.
To ensure prompt payment of penalties, it helps if the process is largely automated and if the vehicle owner rather then the vehicle driver is held liable. The registered owner will receive the violation notice and it is up to them to dispute or pay the ticket. In cases where the registered owner was not driving the vehicle at the time of the offence, it is up to them to name the offending driver so that they can the ticket. Most companies, with company vehicles shared by several drivers, and also rental car agencies, have policies in place whereby the offending driver can be named and subsequently pays the ticket.
Research has found that long-term behavioural effects from enforcement are only achieved if the detection of a violation is followed by immediate feedback or a sanction (for example, see the discussion on how road policing impacts road safety in this link).
For further information on speeding penalties see Section 9.6 of the OECD/ECMT Speed Management Report (here), and GRSP Report Penalties to Improve Road Safety (here).
Speed limits should be set having in mind the safe and appropriate use of a certain stretch of road, for all road users. However, speeds may also need to adapt to different conditions, including weather and current traffic or road users.
Variable speed limits (VSLs), sometimes called dynamic speed limits (DSLs), can assist by changing to local circumstances to slow drivers down. Common applications for VSLs include bad weather conditions, high traffic volumes (congestion management), or increased vulnerable road user activity (such as start and finish times for schools). Sensors can be used to detect when traffic volumes or weather conditions change, or time-based systems can be used for known periods of additional road user activity.
Weather-related VSLs are used where rain, fog, ice, or other factors often occur and might affect road safety. When weather conditions get close to being unsafe, the speed limit is reduced.
Congestion-related VSLs can be used on roads with high traffic volumes and where congestion is likely to occur. When the traffic volume exceeds a certain amount, speed limits are reduced to slow traffic evenly and handle more traffic volume. Contrary to common belief, slowing traffic down in heavy traffic increases the number of cars that can travel on a road and allows a smooth traffic flow, delays the onset of congestion, keeps stop-and-go conditions to a minimum and reduces the number of rear-end collisions.
For periods when there is increased vulnerable road user activity, such as before the start of school and just prior to the finish of school, during shopping hours for retail precincts, or for other areas of activity, time based variable speed limits can be used.
In all cases, the speed limit reduction should also alert the drivers to the onset of unsafe conditions. The changes in VSLs should be automated - not requiring interventions from an operator and can be combined with automated traffic warning, travel-time information or lane control signs.
The VSL system should monitor data from sensors on the roadway and automatically lower speed limits when weather or traffic conditions reach certain limits to keep an even traffic flow at a speed that is reasonable and safe for the current conditions.
In managing speeds, reliable speed and crash data would be ideal.
Speed data can help identify speed-related issues and determine their magnitude and contributing factors. This is crucial for robust and evidence-based speed management. Providing supporting data also helps to earn backing for speed management interventions from local politicians and the general public by clearly showing that speed and speeding are problematic, that speeds are too high and whether speed limits are appropriate for the traffic conditions.
Speed data can be collected through a speed survey which should provide an accurate picture of driver speed behavior in the survey area. The measured speeds of vehicles traveling through the survey area can be used to determine free-flow speeds (mean and 85th percentiles) and to compare the speeds in the survey area to areas outside. They can also be used to determine if driving speeds are excessive and if default or signposted maximum speed limits are inappropriate (too high or too low) for the existing road conditions and surrounding environment. More information on how to conduct a speed survey can be found in Q2.3.
Besides speed data, crash data analysis provides a solid foundation for identifying speeding problems. If possible, at least three whole years of crash data are needed to be able to identify trends. In general, crash data can either be obtained from hospitals and/or police. In some countries, police and hospital data are regularly and systematically combined to give a fuller and more accurate picture of speed-related crashes. Some police crash reports also classify crashes as speed related, which can aid speed related crash identification (although these suggestions for crash cause might not always be correct).
Useful data include not only crash records (number of crashes, types, fatality rates) linked with road condition information, but also results of site reviews/inspections, citation history as well as any information from the public (citizen concerns or surveys) and/or partner organizations (e.g., traffic police). This information should be obtained to determine if there is a speeding issue and, if so, to what extent and from what causes.
However, in many countries such data are not yet available, even though in many instances it is clear that speeds are too high and that speed limits are inappropriate. Where vulnerable road users are seriously injured by vehicles, speeds should be lowered whether data are available or not. Having data is preferable but not a necessary pre-requisite, especially in this kind of situation.
Further information on the importance of road safety data for speed management can be found in the Speed Management Manual. More detailed information on speed data collection can be found here.
Electric scooters, or e-Scooters, are micromobility devices that have been in a wider use in urban environments since the late 2010’s. According to the Royal Society for the Prevention of Accidents (ROSPA), e-Scooters are becoming more and more popular because they:
a) offer more versatile mobility compared to other transport modes,
b) reduce the user’s carbon footprint,
c) are cost-efficient, and
d) are faster than cars in congested urban environments.
On the other hand, in comparison to walking and cycling, e-Scooter use is likely to be more risky, less healthy and active, less environmentally friendly and more costly.
In a systematic review of studies the University of British Columbia concluded that:
the growing popularity of e-Scooter use has potentially led to a rise in eScooter-related injuries, both to riders and other Vulnerable Road Users (VRU), e.g., pedestrians
most reported injuries, 93%, are due to single-user incidents (mainly falls, 95%).
The researchers at the Centre for Accident Research & Road Safety – Queensland (CARRS-Q) have reported that e-Scooter rider speeding is a significant contributor to e-Scooter crash and injury risk. This finding is confirmed by the results of a survey of experts’ opinion as well as e-Scooter injury data and research conducted by the Forum of European Road Safety Research Institutes (FERSI).
e-Scooter Speed Management:
Under the five pillars of the Safe System approach, the e-Scooter speed management recommendations can be summarized as follows.
Because of the nature of their movements and the level of protection against crash forces, e-Scooters are considered Vulnerable Road Users (VRU). Therefore, the speed limit should be 30 kph or lower when they share the road or street with motorized vehicles. For more information on VRUs, refer to Q2.7.
Limit maximum speed of e-Scooters to 15-20 kph depending on the street infrastructure and e-Scooter rider’s age. This is mainly because higher speeds result in greater crash risks (in particular falls) and injury outcomes, both for riders and other VRUs hit by e-Scooters. Research into e-Scooter-related pedestrian injuries suggests that pedestrians with vision and/or hearing impairment, children, the elderly, and distracted pedestrians are more likely to suffer such injuries.
Prohibit e-Scooters from footpaths, or if they must be accommodated on the footpath, limit the maximum speed to 10 kph.
Consider Acoustic Vehicle Alerting Systems (AVAS) for e-Scooters; AVAS generate sound to improve the safety of nearby pedestrians, especially those with hearing or vision impairments.
Enforce posted speeds for e-Scooters, even if only for a short period upon their introduction, to assist awareness and culture/behavior change amongst e-Scooter riders and other road users.
Implement compulsory helmet use and, similar to many EU countries, a minimum-age restriction (e.g., 14 or 15 years of age) owing to the high frequency of falls and head injuries for e-Scooter riders.
Apply Intelligent Speed Adaptation (ISA) and geo-fencing in the design and operation of e-Scooters. Investigate improvement to the stability of e-Scooters, especially for novice riders, as falls are the most frequent cause of e-Scooter rider injuries.
Collect more comprehensive e-Scooter and pedestrian injury crash data to better understand the impact of e-Scooter speed on the associated crashes and injuries. This is also recommended by the International Transport Forum’s report on ‘Safe Micromobility.’
Work zones pose specific risks not only to the road users driving through the complex arrangements of signs, road markings, and lane changes but also to the workers who build, repair, and maintain the roads, and to the communities that live in close proximity. These risks are often the result of conflict between workers and road users for the limited road space available in work zones and the reluctance of many road users to reduce their speeds, despite the change in road space.
Drivers should receive warning far enough in advance from the work zone to allow sufficient time to both understand the information presented to them and adopt the correct driving behavior, but close enough that it is not perceived as premature and disregarded.
Speed reductions in a work zone should always be appropriate to the level of risk presented to workers and all road users. Setting unreasonably low speeds in work zones relative to the risk will result in unnecessary disruption, community dissatisfaction, and ultimately poor driver compliance. Conversely, setting unreasonably high speeds in work zones will result in increased likelihood and severity of crashes.
Lateral safety (the clearances between workers and traffic) is another essential principle to safe and effective speed management in work zones. A high level of lateral safety will allow for traffic to safely pass the work zone at higher speeds. Conversely, a low level of lateral safety will require reduced traffic speeds past the work zone, or other measures to address the reduced clearance, such as a safety barrier system.
On roads where vulnerable road users might be present, they should be given a high priority at all stages of the works. Pedestrians and cyclists must be protected from work activities as well as from passing traffic. If the works involve closure of all or part of a footpath or cycling lane an alternative route needs to be provided. The alternative route should be safe, well-lit, well-ventilated and must include access to adjacent buildings, properties, public areas, and public transport (e.g., bus stops). Suitable delineation devices such as barricades, must be provided to safely separate pedestrians from hazards within the work zone.
Like speed enforcement in other settings, there is no single best method of enforcing speed limits in work zones as different methods should be considered in different contexts. Still, especially in long-term work zones and/or where a risk assessment suggests a particularly high risk due to vehicle speeds or driver compliance, automated speed enforcement should be considered. In this context, point-to-point enforcement over the whole length of the work zone has proved highly effective.
For more information on work zone safety refer to the CAREC Road Safety Engineering Manual 2: Safer Road Works or the UNECE’s TEM Guidelines on Workzone Safety.
The Academic Expert Group that informed the 3rd Global Ministerial Conference on Road Safety identified gender among the areas affected by road safety, together with equity, health, poverty, environment, employment, education, and sustainability of communities. When investigating speeding behaviors and offences, gender is an important consideration, as a thorough literature review demonstrated the overall higher involvement of men in dangerous acts on the road.
According to the SafetyNet Collision Causation Database, men are more often involved in collisions caused by high speed and incorrect direction (including running off the road). In a study on Sex differences in driving and insurance risk, it was highlighted that men were more likely than women to be involved in road crashes resulting from excessive speed, but also that the higher driving speeds of men, and young men in particular, were attributed to their higher involvement in deviant and anti-social behaviors in general. Exceeding speed limits was just one manifestation of this broader pattern, which is supported by several studies.
Men also showed a tendency to be more accepting towards speeding in the SARTRE study of driver attitudes. 29 percent of male survey respondents said that driving 20 kph over the speed limit in a residential area would make driving a more pleasant experience, compared with 23 percent of women. 6 percent of men compared with 3 percent of women admitted that they ‘very often’ or ‘always’ speed in residential areas. A corresponding difference was also apparent in risk perception: 19 percent of men said the risk of being involved in a collision when driving 20 kph over the speed limit in a residential area would not increase, compared with 15 percent of women.
Thus, a series of studies confirm that men’s intentions and behavior towards speeding are more obvious comparing to women, and this is also confirmed when comparing the perception of wrongness of speeding, which shows that women are generally more conscious drivers.
3. Speed management through road engineering
Road engineering activities range from minor improvements to small sections of existing roads, to major road works on regional or inter-regional developments. Road engineering addresses many facets of driving and road use such as human behavior, human expectations, visual cues, road features, lighting, signage, safety barriers etc. Road engineering design objectives include making road use as simple as possible for all road users, reducing the human error on that road, and therefore the likelihood of a crash. Effective design can also reduce the severity of the outcome should a crash occur.
Making the road function/usage and required speed clear through good design will reduce the likelihood of speeding, one of the main causes of road trauma.
For example, when a driver encounters not just lower speed limits but also road features such as well signalized and marked pedestrian crossings, roundabouts, traffic islands or gateway treatments, they become aware of a change in road environment, and more specifically of an increased number of vulnerable road users possibly sharing the same space, and are more likely to lower their speed through the area. Some additional design features that can help you control the road user behavior through engineering are road narrowing, speed platforms/humps or chicanes. A poor road design may not inform road users appropriately. This can lead to dangerous situations, including poor speed selection, last-minute decision-making, or sudden changes causing unpredictable behavior, leading to a higher likelihood of crashes.
Speed humps and other traffic calming must be visible to road users. This is especially important in higher-speed environments. For this reason, they must be implemented in conjunction with appropriate signage and linemarking. Advisory speed signs may be required based on the ‘safe and comfortable maximum speed.’
Learn more about this topic from Europe here and here and Australia.
City areas are densely populated places where people live, meet, work, relax, or entertain. They are characterized by having particularly high numbers of vulnerable road users. The traffic flow is slow due to the high street activity and presence of pedestrians and other vulnerable road users such as cyclists and motorbikes. Furthermore, city areas include ‘special zones’ such as schools, hospitals, shopping streets, public transport hubs etc., where even higher concentrations of vulnerable road users are present.
This can include the elderly, people with disabilities, or equally important, children using the streets as an active playground. Creating an environment that is supportive and safe for children is safe for everyone. Read more about “Designing streets for kids” here.
In places with a large proportion of vulnerable road users and possible conflicts between pedestrians and cars, the speed limit should be no higher than 30 kph. When vulnerable road users are not present and safely separated from the vehicular traffic, and the risk of conflicts with vulnerable road users is low, the speed can be as high as 50 kph.
In these types of areas, traffic calming measures are necessary, such as:
Intersection traffic calming measures:
→ Roundabout or compact roundabouts: horizontal deflection
→ Raised intersections and crossing: vertical deflection
→ Horizontal deflection on approaches to intersection (to be considered at high risk locations)
→ Vehicle activated signs
Midblock traffic calming measures
→ Zebra and pedestrian signalized crossings (noting the effectiveness for each is highly dependent on good compliance by road users, and each crossing type needs to be installed in a suitable location).
→ Raised pedestrian crossing
→ Pedestrian refuges
→ Variable speed limits (VSL), for example, reduced speed limit during school drop off and pick-up time
→ Chicanes: horizontal deflection
→ Textured surfaces.
→ Speed cushion / hump / table: vertical deflection (used at high risk location)
→ Road narrowing (e.g., including through the use of sidewalks)
Learn more on the principles of improving urban road safety in Europe here. Learn more about engineering measures from NACTO here or here. See a Canadian guidance on traffic calming here, and an Australian guidance here. To see what London did to achieve lower speeds see here.
The roads in city outskirt areas are further away from a city or town centers and often in areas of high growth. In some cities, the outskirts are composed of business/commercial land with the population living in single dwellings rather than city multi-dwellings (apartments).
In many parts of the world, lack of planning and investment in infrastructure results in city extensions outpacing improvements in the road network. Travel is often on low-quality roads, with road quality improvements being slower than the increases in traffic, combined with less access to public transport.
This also includes roads leading out of cities where there is growing traffic, but poor provision for safety. There can be a mixture of road users, often because there are inadequate public transport networks. These factors reduce the ability to safely accommodate the traffic and protect its road users. The limitations of the public transport networks result in an increased number of vulnerable road users sharing the same road space as motorized traffic.
Speeds may be higher in these outskirt areas because they are often less developed (or were previously less developed) and they may also be regarded as semi-rural in nature. In such circumstances, maintaining high levels of safety becomes more difficult when travel speeds remain high and the road environment is unforgiving. Higher speeds are recommended only where high-quality infrastructure is provided and where vulnerable road users are not present.
The engineering measures shown below can be implemented when managing speed within city outskirts. Some of these solutions are better suited to high-risk locations (such as the speed cushion) whereas others can be used across the road network. In situations where there are high concentrations of vulnerable road users, some of the solutions more typically used in city centers, or in towns in villages should be used (see section 3.2 and 3.4).
→ Signalized intersection with dedicated pedestrian phase
→ Vehicle activated signs
→ Transverse rumble strips
→ Raised pedestrian crossings
→ Speed cushion / hump / table: vertical deflection (used at high-risk location)
→ Raised pedestrian crossings
→ Road diet (lane narrowing)
→ Reduced speed limit signs
→ Variable speed limits (VSL)
Learn more about achieving lower speeds in urban areas here or here.
Towns and villages are clustered human settlements located away from city and city outskirt areas. While the definitions of 'town' and 'village' vary from country to country, generally a town is considered as an area larger than a village, often with improved infrastructure and availability of more services.
In comparison to a city, a town is generally smaller in size and population. Towns often do not provide all services and facilities (e.g., administrative services and commercial facilities) to its residents, thus requiring movements to and from nearby cities to access some services.
In general, villages are located in rural areas, however, modern urban neighborhoods are also termed as 'urban villages' in some countries. In this FAQ guidance is provided for villages located in rural areas.
Roads in towns and villages are primarily of two types: rural highways routed through towns and villages connecting these areas with urban areas, and local town and village roads which service the area and connect with the rural highways to access services and facilities within towns and villages. Roads within towns and villages need to ensure safe speeds for local traffic, including managing the greater risk that is typically posed by high speed traffic on major through roads, including rural highways.
Rural highways pose significant crash risks to road users on the highway and in towns and villages through which the highway is routing due to the high speed of motorized road users. When reaching a town / village along the highway, after a period of uninterrupted driving at high speed, drivers on rural highways generally underestimate their travelling speeds. This can result in severe crashes when these motorized vehicles encounter vulnerable road users, or local traffic.
These issues can be addressed through the following infrastructure engineering measures used to manage speed:
Rural highways through a town/village
→ Lower speed limits
→ Transverse rumble strips (especially as warnings for subsequent stronger speed managing infrastructure such as speed humps)
→ Textured surfaces
→ Repeater signs
→ Raised traffic signalized intersections
→ Transverse rumble strips
→ Raised pedestrian crossings
→ STOP or GIVE WAY control
→ Speed humps/cushions
Learn more about speeds on roads in town and village area here and here.
Non-built-up areas outside of cities and towns include various road types and speed limits. The road types can vary from motorways, high-speed roads that connect major towns and cities, and lower volume rural roads. The speed limits can range between 90 and 120 kph on motorways and between 70 kph and 100 kph on other roads, and these higher speeds are considered safe where these roads are designed for motorized traffic, and fully segregated from vulnerable road users. Good quality infrastructure is required on higher speed roads to ensure safety. Examples of this infrastructure includes barrier systems, good alignment and cross-section, and well-designed intersections.
It is recommended that pedestrians and cyclists are fully separated from the high speed roads to eliminate interaction and risks e.g. non-motorized lanes or shared user paths. Where this is not possible, speeds can be reduced at key risk locations such as those approaching towns, villages or pedestrian crossings.
When it comes to speed limits, engineering measures should consider two things: the human body’s tolerance levels to the force of an impact and the various components of the highway. Listed below are a range of solutions to manage speed along highways:
o Vehicle activated signs
o Consistent treatment of curves along routes including chevron alignment markers, guideposts, warning signs etc. to provide road users with a self-explaining (see Q3.8) level of curve severity
o Speed advisory signs
o Advance warning signs
o Rumble strips (away from residential areas to avoid noise pollution)
o Lane narrowing
o Wide medians
o Whether activated signs
o Rumble strips (away from residential areas to avoid noise pollution)
→ Gateway treatments when entering towns and villages (see Q3.4). Their purpose is to make it easier to identify entry within a town or village hence increasing compliance with the speed limit
Learn more about infrastructure measures to reduce speed here, case studies from Australia here and here.
A self-explaining road is one where the design of the road tells road users how to safely use it, including the required speed at which they should travel. Various road elements act as visual and physical cues for slower or faster travel. Narrower roadways, physical traffic calming measures, different road surface texture and other design elements give a clear message that slower speeds are required. Wider roadways (including where there are multiple lanes of traffic) give the impression that higher speeds are possible. Consistent application of such measures across different types of roads (especially roads with different road use function) creates clear guidance to road users on their expected behavior including the appropriate speed. It is therefore clear to motorists where low speeds are required, or where higher speeds might be safe.
For example, in urban areas with a high number of vulnerable road users (see Q3.2), a driver will adopt a low speed when effective traffic calming measures such as narrower roadways and raised pavement surfaces are implemented. When entering a town or village (Q3.4), a driver can be provided with a “gateway” type treatment, and supporting infrastructure throughout the town or village such as narrower roadways and raised pavement surfaces, especially where vulnerable road users are present. These designs encourage appropriate behaviors relating to safe speeds.
Learn more about this from CEDR and the European Commission.
A 30 kph zone is a network of urban roads and streets where the speed limit is dropped from the default 50 or 60 kph to 30 kph. Sometimes, speeds of less than 30 kph are used at locations where there are high concentrations of vulnerable road users. Along with 30 kph zones, these are often referred to as ‘low-speed zones’ and areused to improve vulnerable road user safety. Such areas:
→ are mostly located in urban environments;
→ have significant residential, educational or commercial uses (or other land uses that create/attract walking and cycling);
→ have motorized traffic and non-motorized modes of transport mixed; and
→ have more of an access and active transport function than a traffic flow function.
A combination of speed limit setting, speed management tools, road infrastructure interventions and technology can be employed to ensure a maximum 30 kph zone functions safely and effectively. These zones are quite appropriate for residential areas, villages, markets, retirement villages, school zones, hospital precincts, around places of worship, dense urban areas with lots of walking and cycling activities, university hubs, public transport hubs and major train station zones, city centres and Central Business Districts (CBD) and wherever vulnerable road users, especially the elderly and children, are in presence.
That is mainly why the Third Global Ministerial Conference on Road Safety’s Resolution 11 recommends to:
“focus on speed management, including the strengthening of law enforcement to prevent speeding and mandate a maximum road travel speed limit of 30 kph in areas where vulnerable road users and vehicles mix in a frequent and planned manner, except where strong evidence exists that higher speeds are safe, noting that efforts to reduce speed will have a beneficial impact on air quality and climate change as well as being vital to reduce road traffic deaths and injuries.”
Widely implemented across the OECD countries, 30 kph zones are repeatedly shown to improve road safety outcomes for all road users, especially vulnerable road users. Follow these links to find more about the Australian, Swiss, Dutch, German, Norwegian, Finnish, Welsh and Scottish experiences.
Further information on ‘low-speed zones’ can be found here.
Road infrastructure, signage and road marking contribute to the decision-making of motorcyclists, their choice of speed, their risk of being involved in crashes, and in some cases, the severity of injury outcomes. There are some key road safety engineering solutions that are shown to reduce motorcycles’ speed and speeding incidents, and/or mitigating the severity of injury outcomes if a crash occurs:
Safe speed limits: The posted speed limits must be determined in alignment with survivable speeds for all road users. While, because of their extreme exposure to raw crash forces, motorcyclists are likely to suffer severe injury outcomes at almost any speed, adopting and enforcing Safe System speeds across the network will reduce the crash and injury risks.
Traffic calming for motorcyclists: Traffic calming devices including vertical and horizontal calming features can help reduce speeding incidents and road safety risk for motorcyclists. Special consideration is required for calming of motorcycle speeds, as riders may be able to traverse standard calming devices at higher speeds, or even ride around them. In addition, poorly designed traffic calming can be a source of danger to motorcyclists. It is safe practice to:
a. locate vertical traffic calming features such as speed cushions and raised platforms away from turning or braking areas for motorcyclists;
b. locate horizontal traffic calming features such as chicanes in a way that sudden and excessive deviations from a direct motorcycle travelling line are avoided;
c. ensure road marking traffic calming features such as rumble devices have adequate skid resistance and are away from the final braking area on the approach to a hazard; and
d. ensure road humps of all types are properly maintained because a damaged surface could cause motorcycle instability.
Read more about traffic calming measures for motorcyclists here.
High-risk locations treatment: Identifying and addressing locations and road lengths where motorcycle speeding or speeding-related crashes are an issue can prevent the recurrence of these crashes. Reviewing motorcyclist crash history, police reports, conducting site visits, measuring motorcycle speeds and the speeds of other vehicles (given these also impact motorcyclist safety as well), and assessing horizontal and vertical alignments are recommended.
Improved road alignment and delineation: Horizontal geometry, particularly in the case of successive curves, should be consistent with radius, compound curves should be avoided (or clearly signed), and adverse crossfall should not be used where a motorcycle’s operating speed is likely to be high. Better delineation helps drivers of motorcycles stay in their lanes, especially on bends, and avoid collisions. It should be noted that sometimes delineation devices themselves (such as paint and steel sign poles) become risk factors.
In addition to these solutions, there are several road safety infrastructure measures that could be used as complementary tools to motorcyclist speed management measures. Physical separation (dedicated motorcycle lanes), better surface friction and more effective roadside hazard management are just a few examples.
For more details on these main and complementary solutions see:
→ the Austroads’ guide ‘Infrastructure Improvements to Reduce Motorcycle Casualties’ (here);
→ a literature review by the Transportation Working Group of the Asia-Pacific Economic Cooperation (APEC) – ‘A review of potential countermeasures for motorcycle and scooter safety across APEC for project: compendium of best practices on motorcycle and scooter safety’ (here); and
→ a European study on powered two wheelers and safety measures, produced as part of the 2-wheeler behaviour and safety (2-be-safe) project (here).
A forgiving road provides an environment that prevents fatalities and serious injuries, including by mitigating the severity of crashes when they do happen. That means the design of the road environment is well matched to the speed, road user types and degree of road user protection.
The Safe System principles highlight the human body’s ability to tolerate crash forces. The speed should be adapted to the most vulnerable transport mode (e.g., walking and cycling) and the possible crash types. To build a forgiving road system, the human body’s tolerance to impact forces should be used as a guiding principle for selecting speeds:
- → Select a maximum speed of 30 kph where there is a risk of crashes with pedestrians or cyclists.
- → Select a speed of 50 kph where there is a risk for side impact crashes (e.g., at intersections or access points).
- → Select a speed of 70 kph where there is a risk for head on crashes (e.g., if there is no separation between opposing traffic streams).
Where speeds higher than these are required, protection must be provided for road users, including the provision of adequate infrastructure. As examples, this might include:
- → Separation of vehicles in high-speed environments by installing forgiving safety barriers systems to prevent head-on crashes;
- → Ensuring barrier ends are energy absorbant;
- → Roadside clear zones, kept free of fixed, non-frangible hazards;
- → Adding forgiving road furniture, like frangible poles.
Learn more about this from CEDR and the European Transport Safety Council. You can also find more information in this scientific paper.
Driver Feedback Signs (or Dynamic Speed Feedback Signs) may be part of a portable trailer assembly or temporarily mounted on a post. These traffic control devices provide a message to drivers who are exceeding a defined speed limit threshold.
These systems typically consist of a speed-measuring device such as a loop detector, radar, and a message sign, which displays feedback to a driver who is exceeding a predetermined speed. The message can vary from a display indicating the driver’s actual speed, a general message such as SLOW DOWN, or an alternative warning such as activation of flashing lights or a curve warning sign.
While radar speed signs, particularly trailer‐based and portable sign‐mounted versions, can be deployed anywhere, the primary applications include communities, school and business zones, and rural roads – often in combination with other traffic calming signs and markings.
Along with information on the effectiveness of this intervention (see Hallmark et al. (2015), further information is also available here.
There are several road safety engineering tools to manage speed to provide safer outcomes for pedestrians and cyclists. We divide them into midblock (road/street length) and intersection solutions (see also FAQ3.2).
Speed management tools at midblock
- → Traffic calming measures: Traffic calming measures, both horizontal and vertical ones, are shown to help reduce speed to safer levels. Examples include traffic humps, platforms, road narrowing and chicanes. A comprehensive list is discussed in FAQ3.2.
- → Raised pedestrian crossings (30 kph or lower): An effective traffic calming measure, raised pedestrian crossings are a pedestrian crossing placed on a flat top road hump. These should be designed to encourage a speed of not greater than 30 kph through ramp profile and crossing height. Not only does this provides pedestrian (and cyclist) crossing priority, but the raised platform gives further prominence to pedestrians and encourages motorists to slow down on approach to the crossing.
- → Raised threshold platforms at side-streets and driveways: Pedestrians and cyclists crossing side-streets and driveways are at risk of being struck by entering/exiting traffic. By providing continuity of the footpath level (and/or bicycle lane) across the conflict area, the threshold design enhances safety for pedestrians/cyclists. Where there is high pedestrian and/or vehicle volumes, a pedestrian crossing can be added to strengthen pedestrian priority.
- → Shared space or shared zone (10-15 kph): A shared space/zone is a street or network of streets where space is shared by vehicles and pedestrians and other vulnerable road users. Safety is a major priority and appropriate measures and rules are put in place to ensure these vulnerable users receive priority and are protected against vehicle movement.
Speed management tools at intersections
- → Safety platforms (30 kph or lower): Extensively trialed and implemented in the Netherlands, safety platforms are specifically designed road humps that are placed on the approaches to intersections to reduce speed to desirable levels. They are shown to be effective speed management tools for both vulnerable road users and car occupants at intersections.
- → Raised intersections (30 kph or lower): The incorporation of a raised intersection profile (or plateau) into an intersection design has the potential to be transformational in achieving Safe System risk levels, especially if designed to achieve 30 kph speeds. A variety of speed levels could be achieved with the appropriate degree of vertical deflection.
- → Roundabouts with 30 kph raised pedestrian crossings: Urban roundabouts are Safe System aligned for vulnerable road users, provided they incorporate design features specifically for pedestrian and cyclist safety. This means that the approaching speed should be lowered to 30 kph or lower, and the use of raised pedestrian crossing on the approaching lanes is shown to work.
Read more about road safety engineering solutions to manage speed for pedestrian and cyclist safety in these documents by SWOV and Austroads.
According to the International Road Assessment Programme (iRAP), 3,000+ children are killed or seriously injured on the world’s roads daily, often on their journey to school – see more about this here.
Lack of safety, both actual and perceived, is a major factor in the decision of parents to allow their children to walk or cycle to school. The grassroot advocacy group, 30please, discusses this point here.
A school zone is an area near a school, widely used by children. These zones should have reduced speed limits, sometimes during specific hours. Speeds of 30 kph or lower speeds are recommended. These lower speed environments are essential to help decrease the chance of collisions occurring with younger road users, as well as ensuring if things do go wrong, the outcome will not result in a fatality or serious injury.
School zone speed limits are usually applicable during the weekday hours when children go to or from school, and, therefore, are more likely to use roads and streets. Some jurisdictions ensure that school zones speed limits are applicable for the whole time that schools are in session, with buffer times before and after. The speed limit is reinforced by flashing lights in some locations. Where there are larger playground facilities, the speed limits are advised to be effective for longer times or become permanent. In the Canadian Journal of Civil Engineering it was concluded that there is “strong evidence that reducing speed limits to 30 kph in school zones can bring significant safety benefits by reducing vehicular speeds and fatal and injury crashes." Find the abstract of the study here.
School zones are best complemented with ‘Safe Route to School (SRTS)’ programs. SRTS programs are based, amongst other pillars, on road safety engineering and enforcement measures to lower speed to safe to walk/cycle levels for children. These programs apply immediately outside schools, but also on the journey to and from school. The majority of traffic calming and pedestrian and cyclist road safety engineering solutions discussed in our other FAQs also apply here. Read more about engineering solutions for SRTS programs here.
In 2013, the Global Road Safety Partnership (GRSP) launched the ‘Safe to School – Safe to Home’ program. The program has utilized international knowledge and practice on child safety, and involved the input of road safety practitioners from a wide range of industries and the global GRSP Expert Team. Find the program’s case study in Vietnam here.
The key treatment philosophy is to provide drivers and/or riders with information on what to expect in advance of curves for a better response and a safer outcome. Information on the level of curve severity is required, and may not always be obvious to road users due to obstructed sight distance or darkness. Being aware of the risk level in advance of the curve helps road users better better respond to this risk by selecting an appropriate speed.
Different options for improvement can be applied to address speed and reduce crash risk on curves. These measures to address speed at curves are often more effective when applied along a route rather than in isolation.
Various forms of road delineation can be applied to curves along the route, including:
Advisory speed limit signs
Curve warning signs
Curve Alignment Markers (CAM)
Edgelines and centrelines
Raised Reflective Pavement Markers (RRPMs)
Pavement marking, centerline rumble strip, and/or delineations to prevent overtaking
Delineation should be provided according to the Standards and Guidelines of each country. The number of delineation items can be increased to assist road users on the approach of a curve, especially at higher risk locations. For example, reduced spacing of guide posts and RRPMs can be used on the approach to a curve or oversized signs installed at high-risk curves. High risk curves tend to be those requiring significant reductions in vehicle speed to safely negotiate the curve. This can be determined proactively (the preferred approach) or by assessing crash history at curve.
Example of road delineation products:
Various technology-based applications can also be considered to assist road users in regulating their speed at curves. As an example, Vehicle Activated Signs (VAS) can be used to aid road users in selecting an appropriate speed, by enhancing driver awareness of a hazard, including at high-risk curves:
Electronic speed displays or "Your speed'” signs (left image below) are placed beside the road. The equipment measures the individual driver’s speed and displays this as they approach. In some instances, the speed display flashes if the road user exceeds a safe speed threshold.
Electronic speed displays or "Too Fast / Slow Down” signs (middle image below) functioning on the same principle as “Your speed” signs and having the same intent to reduce speeds if road users are exceeding a predetermined threshold speed.
Sensor-triggered speed limit signs (right image below). These are electronic speed limit signs that are activated by approaching vehicles. Read more about this technology here and here. Also see Q3.10.
Other infrastructure improvements can be implemented, often as part of broader improvements such as road rehabilitation. Some examples include: roadside hazard removal, sight distance improvements, cross-fall correction, wide centrelines or safety barrier installation. Speed limit reduction may also be applied on a route basis, supported by signage and other necessary measures.
You can find further information about speed management at curves here and here.
Road networks around the world have in common that they are typically extensive. They need to handle lots of different road user groups, cover a variety of road environments of which some are very challenging, and they often have crashes that are spread widely across the network. Although upgrading roads to a higher standard would undoubtedly bring substantial safety benefits, it is very difficult to invest the required amount in these upgrades across the whole network where changes are required.
Therefore, providing speeds that are safe and appropriate is likely to be the quickest and most effective way to prevent deaths and serious injuries on the highest risk road sections on these networks. By all means, greater investment should be made to improve the quality of roads, but until these investments are made, speed limits can be reduced to provide a greater level of safety.
It is also notable that investments in lower speeds can be more cost beneficial than investments in infrastructure, particularly when the focus is on improved safety outcomes. Especially on lower volume roads, it is likely that lower speeds will remain the most economically viable option.
A study from South Australia (documented here) compared the cost of infrastructure improvements required to bring about the same safety benefit as a 10 kph reduction in speed limit. On the rural 110 kph state highway network, the cost to reach the expected 20% reduction was AU$1 million for the speed limit change, while the required infrastructure investment to obtain the same benefit would have been AU$ 8 billion.
At the same time, we need to consider that high speeds have a negative impact beyond road safety affecting Greenhouse Gas emissions also, as presented in FAQ 1.8, and future investments in road infrastructure should be in line with the Paris Alignment.
In-depth studies highlight a strong relationship between crash occurrence and the characteristics and conditions of the road surface, especially in relation to speed. The quality of the road surface influences the traffic conditions, as reduced contact of the tires with the surface limits maneuverability and can lead to crashes. Appropriate roughness, flatness and impermeability of the road surface are very important for ensuring the comfort and safety of traffic, especially for high(er) speed roads.
Roughness depends on several factors, such as micro texture, macro texture, mega texture and non-uniformity. These are directly affected by the materials used in the asphalt mixture, including the quality of the aggregates, the sand and possible contamination during civil works or operation, all impacting the stopping distance at various speeds. For example, a study from Romania shows that just by selecting different types of aggregates for the same type of asphalt mixture, there are considerable differences between the stopping sight distance at the same design speed. For a driving speed of 130 kph, the stopping site distance can vary by 17 metres for flat grade, and go up to 24 metres for a 10% downgrade slope. The differences are smaller at lower speeds, but the study still reveals that the quality of the road surface impacts the stopping sight distance.
The complexity of tire-road surface contact and stopping sight distance increases considerably during wet weather. Water present on the roadway surface is an important element for traffic safety, as it can have an effect on the driver’s visibility and can also facilitate the occurrence of aquaplaning. The latter is an especially dangerous phenomenon consisting of the tire gliding on the water film present on the road surface. It occurs under specific conditions, when the vehicle exceeds a certain speed, and also when the shape of the tire and the texture of the road surface do not favor rapid water drainage. In such situations, a continuous water film of variable depth appears between the tire and the road surface, and the friction coefficient is reduced to 0.1, especially when the wheels are locked by braking. Although an exact equation for the accurate calculation of the speed at which aquaplaning occurs has yet to be developed, empirical studies have revealed that the driver loses control of the steering wheel because of accumulation of water on the carriageway at a speed of at least 85 kph, on a water film of at least 2.5 mm in depth, at a distance of more than 9 meters. With abnormally heavy rains happening more often due to climate change and the increase in the number of road crashes during these weather conditions, technical solutions are required to proactively address and prevent aquaplaning in vulnerable locations. See here some possible solutions to prevent aquaplaning.
Find out more about the importance of the road surface in the Road Safety Toolkit.
All road types have potential dangers in regard to road safety outcomes, and speeding in any environment can be dangerous. In higher-speed environments (such as on rural roads or inter-city highways) if any mistake is made, the consequence can be severe.
This is because the human body can only withstand certain impact forces (see Q1.4). If these forces are exceeded, the chance of death or serious injury will increase. In addition, when travelling at high speeds, it is easier to make mistakes. This is because there is less time for drivers to react to hazards, and it also takes longer to brake leading to increased stopping distances. Speeding therefore increases both the likelihood of a crash, and the severity of the crash outcomes.
However, even at lower speeds, speeding can be dangerous. In city environments, the traffic mix is different, and there are typically a greater number of vulnerable road users, including pedestrians and cyclists. As indicated in Q1.4, when vulnerable road users are struck by motorized vehicles at speeds greater than 30 kph, the chance of severe injury or even death increases substantially. Therefore, speeding in these environments can also have significant negative outcomes.
Learn more about the impact of speed from research in Europe, the Americas, Australia and Canada.
The link between changes in speed and road safety outcomes is very clear, and as shown in other FAQs (see Q1.4, Q1.7 and Q1.9), even a small increase in speed for any given road will typically lead to an increase in the number of crashes and the severity of their outcomes, whereas a reduction in speed leads to a reduction in such crashes. However, this does not necessarily mean that the fastest roads are the least safe.
The safest roads in terms of number of fatalities and serious injuries are often motorways (freeways), especially if well designed. Good design on these roads includes ensuring there is safe access for vehicles entering and exiting from the roadway (‘grade separated’ intersections), separation between vehicles travelling in opposite directions and to roadside hazards (for instance through the use of barrier systems), only mild curvature, restricted access in combination with alternative routes for vulnerable road users (e.g., pedestrians and cyclists) amongst other features. This requires the provision of road infrastructure to ensure safe travel. A key point is that without this safe infrastructure, the higher speeds would not be safe, highlighting the strong interaction between speed, infrastructure and safety outcomes. In situations where higher speed is a requirement, infrastructure is needed to support safe mobility at these higher speeds. This same principle also applies for other types of roads. Where there are vulnerable road users present, speeds need to be low (30 kph or less as discussed in Q2.7). However, where safe road infrastructure is provided, particularly safe infrastructure for vulnerable road users, there may be the ability to travel safely at higher speeds. For instance, if a segregated bicycle path is provided, it may be possible to have higher speeds for motorized vehicles on the main carriageway.
One implication of this interaction between speed, infrastructure and safety outcomes is that on lower quality roads, lower speeds are required for safe travel. Outside of urban areas, it is often the case that high default speeds (e.g., 100 kph) are used, regardless of the quality of the infrastructure. For safe travel, these higher speeds should only be permitted where infrastructure provides a forgiving road environment. Where safe road infrastructure is missing (for instance, narrow cross sections with no separation between opposing traffic, unprotected roadside hazards, and poor safety provision at intersections) much lower speeds are required.
Lastly, as mentioned above, an increase in speed for any given road (i.e., holding all other elements the same except the speed) will typically lead to an increase in the number of crashes and the severity of their outcomes, regardless of the road type. Whether the road be in a local urban area, or an inter-urban highway, unless infrastructure improvements are made, an increase in speeds will lead to an increase in the risk of death and serious injury.
The link between speed, infrastructure and safety is well explained in the Sustainable Safety approach from the Netherlands (see a summary here). For a useful research study highlighting increased risk from speed increase on rural, single carriageway roads of different quality, see here.
Evidence shows that traffic lane and shoulder width play an important role in a driver’s speed choice. Wider traffic lanes and shoulders encourage faster driving, while narrower roads (including fewer lanes), and narrower lanes lead to lower speeds. These lower speeds lead to lower crash rates.
Wider traffic lanes may appear intuitively safer as they provide some buffer room for drivers that lose concentration, are momentarily distracted, or make other errors while on the road. This reduction in risk is likely, but only to a limited extent, particularly for streets in urban areas. The issue largely comes down to speed: when drivers have more space, cars go faster; when cars go faster, more crashes will happen, and they will do more harm. When the benefits from wider lanes are outweighed by the disbenefits from higher speeds, crash risk will increase.
This is not only valid for narrowing lanes but also for narrowing roads, e.g., by reducing the number of lanes. These lane reductions include ‘road diets’. A ‘road diet’ is used to improve safety or to provide space for other modes of travel, such as sidewalks or cycling lanes. An existing two-way undivided road with a total of four lanes might be converted into a three-lane segment consisting of two through lanes and a center two-way turn lane. The turn lane improves safety by protecting mid-block turning motorists, by reducing the crossing distance for pedestrians, and by decreasing travel speeds and thus crash severity.
Thus, the ‘wider is safer’-approach should be replaced with a ‘narrower is safer’ approach, especially in urban environments, given the empirical evidence. Narrower lane widths, combined with other livable streets elements in urban areas, result in less aggressive driving and increase the ability to slow or stop a vehicle over a shorter distance to avoid a crash.
For more information on the influence of lane width on speed look here. For information on ‘road diets’ look here.
4. Speed management through traditional enforcement
Because speed limits and enforcement are intertwined, it is important for the road authority to liaise with enforcement personnel before setting a speed limit for a location. Enforcement personnel have experience and unique insights into the enforceability of speed limits that may be used to ensure that rational speed limits are applied. They also have local knowledge of the location of crashes and the locations where speeding is prevalent.
Traffic Enforcement is an important and necessary measure for speed management, and is based on giving drivers and riders the feeling that they are monitored, and likely to be caught if they don’t obey the law. In many countries speed enforcement has significantly evolved over the past 10 years with a general increase in the focus of enforcement efforts and the increasingly widespread introduction of automatic speed control, which does give a new dimension to the enforcement effort. If undertaken appropriately, speed enforcement can be a very powerful measure (deterrent) that contributes directly to reducing the incidence of speeding and consequently, the frequency and severity of crashes.
The objectives of the enforcement component are to:
→ Act as a deterrent to all road users which are more likely to disobey road rules and present a danger to others;
→ Maximize the effectiveness of enforcement activities by integrating them with engineering and promotional efforts;
→ Raise understanding of the importance of police enforcement;
→ Encourage the participation of the police in an integrated and comprehensive traffic safety strategy.
Enforcement can yield immediate and significant impacts. Not only is this important from a crash prevention perspective, but also essential to maintain the ongoing enthusiasm of the project participants. It can also complement and maximize the effectiveness of other measures e.g. infrastructure, education.
ETSC states “Since excessive or inappropriate speed is a primary factor in about one third of road deaths and an aggravating factor in many more, speed enforcement will remain essential as long as the speed problem is not solved in a structural way by road design, engineering measures and in-vehicle technology.” Link to the full report here.
Also, learn more about the effects of speed enforcement on road safety here.
In addition to detecting offenders, one of the major roles of enforcement in speed management is deterring unsafe behaviors. The level of deterrence is related not only to the actual level of enforcement, but also to the perceived level of enforcement and the perceived deterring value of the penalties. Publicity promoting enforcement can increase the perceived level of enforcement and thus further reduce unsafe behaviors.
General deterrence is the impact of the threat of legal punishment on the greater public at large, influencing a potential traffic law offender, through fear of detection without actual detection of that potential offender. Therefore, operations employing general deterrence mechanisms target all road users irrespective of whether they have previously offended. General deterrence programs have the potential to influence the behavior of all road users.
Specific deterrence is the impact of the punishment on those who are apprehended. Therefore, the potential impact of a specific deterrence program may be more limited than that of programs relying on the general deterrence mechanism. See here a study from Cameron & Sanderson (1982).
Thus, general deterrence results from the perception of the public that traffic laws are enforced and that there is a risk of detection and punishment when traffic laws are violated. Specific deterrence results from actual experiences with detection, prosecution, and punishment of offenders.
The general assumption underlying police enforcement is that it should primarily aim at general deterrence, which is first and foremost achieved by increasing the subjective risk of apprehension.
Covert, mobile speed camera enforcement programs may provide a more generalized deterrent effect and may have the added benefit that drivers are less likely to know precisely when and where cameras are operating. Speed enforcement activities are best repeated frequently, at irregular intervals and with different intensities. Higher intensities generally result in larger effects.
Overall, traffic enforcement will be more effective if it:
→ is accompanied with awareness raising campaigns;
→ takes place over long periods;
→ is predictable and difficult to avoid; and
→ combines high-visibility with low-visibility activities.
To maximize road safety effects, traffic law enforcement should, first and foremost, prevent violations that are proven to be linked to the number or severity of crashes (such as speeding). There is no single best method for enforcing speeds since different forms should be considered in different contexts. The following types of enforcement (manual or automated approaches), which should always accompany any change in speed limit, may be used:
→ Stationary patrols use marked or unmarked vehicles stopped at roadside to monitor traffic speeds.
→ Mobile patrols use marked or unmarked vehicles traveling with traffic to detect specific violators in the immediate vicinity of a moving patrol car.
→ Highly visible enforcement strategies use multiple stationary or mobile marked patrol cars to remind the public that enforcement is present and to increase the actual and perceived risk of detection among the driving public.
→ Stealth methods use unmarked, unconventional, or hidden vehicles to monitor speeds and apprehend speeders.
→ Automated speed enforcement (ASE) uses equipment that monitors speeds and photographs offenders to produce a citation that is later mailed to the registered owner of the offending vehicle.
→ Aerial speed enforcement from aircraft measures vehicle speeds based on the time it takes a vehicle to travel between two or more pavement markings spaced a known distance apart. Identifying information regarding a violator’s car type, location, and cited speed is transmitted to officers on the ground, who issue citations.
Evidence has shown that enforcement through the use of automated speed control is most-effective at reducing speeds. It is important to mention that where countries have changed their speed limits, but have taken little action to enforce them or the control speeds through engineering, there have been very limited benefits. You can read more about the effectiveness of speed cameras in preventing road traffic collisions and related casualties here.
Generally, the public perceives that there is a cushion or threshold above the speed limit in which officers will not cite offenders. While an officer may provide some discretion in whether or not to issue a ticket for a speed that is just a small amount over the speed limit, it should be recognized that the speed limit has been set as a certain level for the purpose of preventing crashes and reducing injuries. Whatever speed limit has been adopted, it is critical that police enforce as close to that limit as possible due to the substantial sensitivity of fatal crashes to very small increases in mean speed. Extensive research has established that even a one percent variation in travel speeds can have a substantial impact on severe crash outcomes (see FAQ1.9).
Victoria, Australia has had success with a program that tightened enforcement tolerances as part of an overall speed management package that included automated and other enforcement, publicity, and penalty restructuring . You can read more about here.
Also, a recent experiment in Finland found that lowering the enforcement threshold of fixed speed camera enforcement on a rural two-lane road from 20 kph above the limit to 4 kph above the limit (advertised as zero tolerance) and publicity of the measure reduced mean speeds by 2.5 kph and speed variance by 1.1 kph in comparison with a similar, camera-enforced corridor where the threshold was not reduced (Luoma, Rajamäki, & Malvivuo, 2012). The percentage of vehicles exceeding the speed limit was reduced from 23% to 10%, so deterrence of speeding was increased without increasing the processed citations (police or administrative burden). The speed effect of the reduced threshold was within the range of effect of the initial implementation of the automated camera enforcement.
In summary, a little bit of speed makes a massive difference when someone makes a mistake!
There are multiple reasons why speed enforcement works better in some countries than others, and some of them include:
Political will: A political environment prioritizing road safety, including speed enforcement, and providing adequate resourcing is an essential requirement. This prioritization varies immensely around the world. Even in many high-income countries, it is often challenging to convince the government of the importance of dedicating resources to speed management.
Crash and speed data: The lack of speed data and the under-reporting of crash data, particularly in low- and middle-income countries, is a significant issue and impedes the successful management of road safety overall, and speed management in particular. Without data, it is difficult or even impossible to select those stretches of road where speeding actually is a road safety issue and enforcement should take place.
Speed limits: Speed limits are the means by which legal sanctions can be brought to bear on those who drive faster than is appropriate and safe on the roads. Currently, speed limits vary across the world. Many road authorities in high-, middle- and low-income countries have no speed limits posted on their roads, consequently, the level of enforcement also varies. Levels of compliance depend on many factors, but credible speed limits (within the Safe system limits) can improve compliance levels.
Financial – The amount of funding dedicated to traffic enforcement varies greatly between countries. For many countries, leaders have not yet recognized or acknowledged the drain on health care and other costs and the positive impact that might be gained by enforcing speed limits, with the result of savings gained through fewer deaths and injuries resulting from speed-related crashes.
Human – Even in high-income countries, decision-makers often do not recognize the value of traffic speed enforcement, suggesting instead that there are other policing priorities.
Training of police – The importance of traffic speed enforcement for road safety and the collection and processing of crash data should be an integral part of police training.
Dedication of necessary financial and human resources to the traffic police is essential for ongoing speed enforcement.
For further information on effective enforcement, see additional guidance from the US here and Europe here.
There are several tactical approaches adopted by most law enforcement agencies to increase motorist compliance with speed limits: stationary patrols, mobile patrols, highly visible and stealth methods (for further information please see Q4.4)
Since there will never be sufficient personnel to manage any (and all) of these methods, many countries have moved or are moving to Automated Speed Enforcement (ASE). The Police Department should identify an individual who organizes and schedules all types of training for traffic enforcement personnel. For those working in manual speed enforcement this should include the correct use of handheld equipment and the importance of accurate speedometers and the calibration of these. Further training should be undertaken when moving into automated enforcement programs.
ASE uses equipment that monitors speeds and photographs offenders to produce a citation that is later mailed to the registered owner of the offending vehicle.
There are advantages and disadvantages to physical policing:
→ Offenders are immediately stopped by the police
→ Offenders receive immediate feedback – a teachable moment!
→ Opportunity to educate the driver as to why they are enforcing speed limits
→ If offenders are at a highly visible location, the perception by other drivers of being caught can be increased.
→ Physical policing is far more labor-intensive and so it is virtually impossible to reach the same level of enforcement
→ Because of this the actual as opposed to the perceived risk of being caught is much smaller
→ A motorized police patrol follows the traffic stream and therefore has a relatively small chance of detecting a speed violator. It also needs to follow that car for a sufficiently long time to determine the level of speeding reliably. If multiple cars are speeding, it is usually impossible to stop all of them.
Random Road Watch (RRW) is a type of physical policing of random enforcement within a designated network or area. This technique randomly schedules levels of enforcement with the goal of realizing long-term, widespread coverage over a road network. A RRW program in Queensland, Australia produced a 31% reduction in fatal crashes on the roads included in the program. The benefit/cost ratio for the program was estimated to be 55:1. Read more about this here.
As part of the overall enforcement policy, an important quality aspect should include the credibility of enforcement.
For further information on effective enforcement, see some resources from the USA here and Europe here. You can read more about the effectiveness of speed cameras in preventing road traffic collisions and related casualties here.
Many countries are unable to fund or implement a fully automated enforcement program, but this should not prevent them from using other forms of enforcement. They should also take steps to make automated speed enforcement possible (see here for a guide for Determining Readiness for Speed Cameras and Other Automated Enforcement).
More traditional speed enforcement methods (also see Q4.4 for further details) include:
→ Stationary patrols (marked or unmarked vehicles stopped at roadside to monitor traffic speeds)
→ Mobile patrols (marked or unmarked vehicles traveling with traffic to detect specific violators in the immediate vicinity of a moving patrol car)
→ Highly visible methods (multiple stationary or mobile marked patrol cars to remind the public that enforcement is present)
→ Stealth methods (unmarked, unconventional, or hidden vehicles to monitor speeds and apprehend speeders).
For further information on effective enforcement, see here and here.
With appropriate penalty regimes and publicity, deterrence-based enforcement has been shown to consistently achieve positive long-term behavioral change in drivers and the general population. However, due to the length of the rural road network, enforcement by conventional means is not always ideal or practical. Rural enforcement programs need to utilize randomized scheduling or deployment methods to enable low levels of police presence to achieve more widespread coverage of vast road networks (see here a resource on this topic).
Police enforcement strategies are especially important given the contribution of inappropriate and excessive speed to road crashes in rural and remote areas. So, as the rural road network is so vast, automated enforcement technologies (i.e., speed cameras) that require minimal staff to operate should be considered.
In many instances providing an adequate road infrastructure will help drivers to choose the ‘right’ (safe) speed and stop people speeding.
For more information see here.
Excessive and inappropriate motorcyclist speed is common and accountable for a significant part of motorcyclist fatalities and serious injuries (see FAQ 1.16).
Effective enforcement can lead to a rapid reduction in motorcyclist fatalities and serious injuries. However, motorcyclist non-compliance with speed limits is not effectively captured by the current enforcement system because:
- → their maneuverability and speed means that they are difficult to catch and stop when an offence is detected by traditional enforcement;
- → motorcycles are not typically required to have a license plate in front and therefore remain unidentified by safety cameras that photograph from the front, further complicated if the rider is wearing a full-face helmet;
- → not all motorcycles are registered (especially in LMICs) and the identity of the rider is hard to establish if required; and
- → the motorcycle license plate is smaller than that of cars, which makes them unreadable for certain camera systems.
These technical issues in relation to motorcyclist speed enforcement must be resolved to enhance the effectiveness of motorcycle speed enforcement programs. Read more about this here.
There are some practical solutions to address these obstacles such as: a) developing motorcycle police enforcement units, and b) using more versatile enforcement tools such as speed guns. These two approaches address the issue of “motorcycle maneuverability and speed.”
Read more about an extensive study where speed guns were used to measure the speed of motorcycles here.
For more technical solutions to improve automated motorcyclist speed enforcement, refer to FAQ 5.2.
Speed enforcement is most effective when there is a mix of highly visible (overt) and less visible (covert) activities and when this continues over a long time period. This way, enforcement is more difficult to avoid and unpredictable.
A number of jurisdictions have had success using non-traditional speed enforcement platforms, including unmarked and unconventional vehicles equipped with mobile video cameras to detect aggressive drivers and stationary speed enforcement using bucket trucks, pickups, and other maintenance-type vehicles from which the speed measurement equipment was operated (Covert enforcement).
Stealth methods use unmarked, unconventional, or hidden vehicles to monitor speeds and apprehend speeders. FAQ5.14, in the section on automated enforcement discusses the use of covert speed camera which seeks to achieve similar outcomes. These methods of detection often reflect how seriously a community or law enforcement agency views speeding. These methods increase uncertainty about the location and timing of enforcement and may result in a greater general deterrent effect among drivers who are aware of this enforcement technique. However, they may have a lesser effect on unfamiliar drivers (i.e. those not aware of the level of enforcement) than visible enforcement. Widespread campaigns should be used in combination with unmarked cars to maximize deterrent effectiveness (see FAQ 7.1).
For more information see here.
Traffic crashes are a leading cause of death, typically causing more annual deaths than crime, and generating a tremendous economic impact. Because of this community impact and the role that speed plays in serious traffic crashes, police resources are required for addressing this speed enforcement issue.
When the community is convinced that the issue of speeding is an important one to understand, they will then be prepared to learn more about it and support actions to reduce the problem. This information can be conveyed to the public over time using mechanisms that are in accord with local customs and supported in a variety of ways to achieve broad awareness of the message and its seriousness. The community needs to understand why speed compliance is being sought, what the benefits are and why it is necessary for them to modify their behavior. It may be best to start public information campaigns about speed.
In the UK, residents were invited to rate speeding in traffic against 15 other anti-social behaviors as part of the face to face British Crime Survey (reported in Poulter & McKenna, 2007). The results indicated that speeding traffic was considered as the largest problem in local communities, regardless of age or gender of the respondents. In a second, smaller mail survey, respondents also provided strong support for enforcement on residential streets, suggesting that even travelling just over the speed limit on residential streets was unacceptable.
An ESRA survey with a total of 35,000 respondents across 32 countries showed that most road users all over the world are aware of speeding being one main cause of a road crash and think speeding to be an unacceptable behavior. Less than 20 percent of the respondents found it acceptable to drive faster than the speed limit. For built-up areas this number decreased to less than 10 percent. In addition, up to 90 percent of the respondents suggested that traffic rules on speeding should be stricter. To find more details, see the report at this link.
For further general information on speed enforcement, see here.
Even though speed enforcement plays an important role in speed management (see Q 4.2) there are some limitations to the use of traditional speed enforcement methods.
A main limitation is that only parts of the whole road network can be monitored by enforcement activities. Often only the most dangerous stretches of roads are checked for speed and only a limited number of speeding drivers are detected due to limited resources – both personnel and equipment. Especially on high-risk roads there is also the issue of safety for those enforcing which might limit enforcement activities.
Another limitation of traditional police enforcement is encountered as the effects on speed are often found only close to the site where police measure speed or on those road stretches where drivers expect police to be present. Drivers reduce speeds when they see traditional enforcement activities being carried out mainly because they fear fines and not out of inner conviction. Thus, they will slow down on roads where they anticipate and watch for traditional enforcement activities but maintain their normal driving style on roads where they do not suspect such activities. Driver attitudes to speed do not change based on enforcement, and so when enforcement is not perceived to be present, it has little impact on driver behavior. Enforcement and fines will have much more effect if they are integrated with promotional efforts and supported through changes to the road environment (see FAQ 4.2).
For further reference see this link.
5. Speed management through automated enforcement
Automated speed enforcement (ASE) systems are an important element in speed management and can be a highly effective countermeasure to prevent speeding-related crashes. However, ASE is a supplement to, not a replacement for, traditional enforcement operations. Advantages of ASE include: the ability to increase safety for law enforcement officers by implementing ASE in areas where traditional traffic stops are dangerous or infeasible due to roadway design, the ability to continuously enforce the speed limit (24 hours, 7 days a week), reduced opportunity for corrupt behaviors to avoid a legal penalty, and reductions in traffic congestion sometimes caused by driver distraction at traffic stops.
ASE is a tool that can enhance the capabilities of traffic law enforcement. ASE will supplement, rather than replace, traffic stops by law enforcement officers. The public should be made aware that ASE is used to improve safety, not to generate revenue or impose “big brother” surveillance. Saying this will not necessarily make it so in the eyes of the public, so it is important to explain how each element of the ASE program puts safety first and how controls are in place to prevent misuse of the system. ASE programs worldwide have demonstrated the ability to reduce speeding and crashes beyond the effects observed with traditional speed enforcement alone. Conducting evaluations to show that ASE has reduced deaths and injuries also helps sustain the position that ASE is for road safety, and helps sustain political will for ASE.
All ASE systems have three basic components: a speed measuring component, a data processing and storage component, and an image capture component.
Speed-Measuring - Speed-measuring requires the ability to detect and discriminate individual vehicles on a roadway and measure their speeds in real time. The accuracy of speed-measuring devices is crucial. Most speed-measuring devices are equally accurate measuring approaching or receding traffic speeds and are accurate to within 1 kph when used properly. Emerging technologies are expanding the versatility of speed-measuring devices and target vehicle discrimination. For instance, scanning lidar (a system that works in a similar way to radar, but by using the light from laser), allows lidar to be used on multiple lanes and two directions of travel simultaneously. Speed measurement devices must be calibrated and tested before their first use and then retested on a regular basis, preferably by an independent laboratory.
Data processing and storage - The data processing and storage component is a computer that receives data from the speed-measuring unit and compares the speed data against the threshold that was set to define violations in real time. If a vehicle’s speed exceeds the threshold, the unit identifies the vehicle as a violator and triggers the camera to photograph the vehicle. Additional information such as time, date, and operator-entered information is also recorded with the speed data.
Image capture - The image capture component includes one or more cameras that photograph the speed violation in progress when they are triggered by the computer. The photographs must include a legible image of the license plate and, if driver identification is required, a clear image of the driver’s face. A fast shutter speed and high image resolution are essential features. Digital photographs are easy to transfer and reproduce electronically, which can save time and effort during violation processing. However, extra care is necessary to ensure the integrity of photographic evidence.
ASE systems include:
→ fixed cameras, which continually monitor traffic speeds without an operator;
→ semi-fixed cameras, with cameras that are rotated between housings resulting in housings with active cameras and ‘dummy housings’ without cameras;
→ mobile camera operations, most often deployed in vehicles with or without enforcement agents present; and
→ average speed enforcement systems that measure average speed between two check points on a roadway, also known as speed and distance cameras or point to point cameras.
For additional information refer to NHTSA Speed Enforcement Camera Systems Operational Guidelines. For a guide to determine Automated Speed Enforcement readiness see here.
The following are some of the advantages and disadvantages of speed cameras.
For a guide to determine Automated Speed Enforcement readiness see here.
Speed cameras are an important part of overall speed management, leading to improvements in safety as well as other societal benefits. Speed cameras have additional benefits over traditional forms of enforcement due to the fact there will always be a shortage of police officers everywhere dedicated to traffic duties, especially dedicated to speed enforcement.
For a guide to determine Automated Speed Enforcement readiness see here.
Yes, the consistency of reported reductions in speed and crash outcomes across various studies show that speed cameras are a worthwhile intervention for reducing the number of road traffic injuries and deaths. Examples are presented below:
The Centre for Disease Control in the US identifies several evaluations showing the effectiveness.The best-controlled studies suggest injury crash reductions are likely to be in the range of 20 to 25 percent at conspicuous, fixed camera sites. Covert, mobile enforcement programs also result in significant crash reductions area-wide. See here.
In addition, the British Medical Journal reports the results of 17 observational studies on the topic. In these studies, reductions in outcomes ranged from 5% to 69% for collisions, 12% to 65% for injuries, and 17% to 71% for deaths in the immediate vicinity of camera sites. The reductions over wider geographical areas were of a similar order of magnitude as seen here.
The Cocrane Library also publishes a variety of research of the effectiveness of speed cameras in reducing speeds and reducing the frequency and severity of crashes. You can learn more here.
The simple answer is NO. Speed cameras are a supplement to, not a replacement for, traditional enforcement operations. In fact, there are some benefits to be gained from conducting manual enforcement. These include:
→ When a driver is stopped by a police officer, the driver receives immediate feedback on the infraction;
→ The Police can explain the risk of speeding to the driver and explain the importance of the speed limit and that compliance results in fewer deaths and injuries;
→ Clearly visible enforcement can increase others’ perceptions of being detected (increasing general deterrence);
→ The driver may be identified as a disqualified driver or a “wanted person”; (many career criminals have been apprehended through manual police checks); andIn addition, other offences may be detected -e.g. checks for breath test, driver license, vehicle safety, etc. in addition to other non-traffic crimes.
Experience is showing that a blended “general deterrence” method, combining modern automated technology, the use of number plate recognition cameras in addition to overt policing methods in a layered approach is required. This ‘layered’ approach to enforcement is demonstrated in the following diagram from the Police Federation in the UK (see link here):
Learn more about speed cameras here while general information about enforcement can be found here.
There are several steps that need to be considered when developing an Automated Speed Enforcement Program.
Legal authority is essential for ASE programs. While the benefits of these programs are widely recognized, there remain reasons why some jurisdictions are unable to proceed. These include:
→ Due process. Some critics have alleged that automated enforcement violates the right to due process.
→ Equal protection. Other critics argue that automated enforcement violates equal protection.
→ Privacy. Driver identification is also likely to raise concerns about individual privacy. Although some people believe that photographing the driver’s face is an invasion of privacy, the general opinion of the courts has been that driving is a regulated activity in a public space, and therefore photographing drivers is not an invasion of privacy.
b) Identify speeding-related safety problems
The first step in planning the operations of an ASE program is to identify the speeding-related safety problems and attitudes that the ASE program will be designed to address. Measures that reflect a speeding problem include speeding-related crashes, excessive speeds, speed variance, and citizen complaints. Speeding-related crashes are the most direct indicator of a safety problem at a particular location. With data on crash history and excessive speeds, it is possible to determine where the speeding-related safety problem is located.
c) Develop a strategic ASE plan
A strategic plan for ASE should provide the link between the ASE program’s overarching objectives (e.g., to reduce the occurrence of speeding and speeding-related crashes) and the short-term and long-term benchmarks that indicate the degree of success in achieving objectives (e.g., the amount of reduction in speeding and crashes at each deployment location). Although program objectives should be tailored to the specific speeding-related safety problem in the community, there are general objectives that all ASE programs should strive to achieve. These are identified in the NHTSA (National Highway Traffic Safety Administration) US – Speed Enforcement Camera Systems Operational Guidelines.
Additional objectives might be more specific to the needs or restrictions of the jurisdiction (e.g., “Reduce speeding in school zones”). Everyone involved in the ASE program must share these objectives and work to achieve them for the program to be fully successful. The strategic plan should emphasize that it is important to avoid rushing to begin enforcement and should consider the long-term direction of the program, including contingencies for future expansion and improvement. Most successful ASE programs started with a minimal ASE presence and expanded their programs as the public came to accept the technology and as program participants gained experience and improved operations.
d) Identify countermeasures
Enforcement is only one component of a comprehensive speed management strategy. It is essential that the strategic enforcement plan combines all the other components. Roles and responsibilities should be clearly delineated, and the purpose of each countermeasure should be explained to achieve buy-in from everyone who is involved in confronting the problems caused by speeding.
e) Obtain interagency and community support
ASE is an inherently cooperative venture. A committee or advisory panel of stakeholder representatives should be formed during the planning process to guide program development and ensure that stakeholders can provide input from their unique perspectives.
Depending upon the structure of the ASE program, there may be other people or organizations involved in its planning and operations, such as experts in technology, information systems, finance, and contracting. A vendor representative may also be involved after a vendor is selected.
It is also essential at the very outset to ensure the public understand this is a program focused in reducing speeding and relevant crashes and injuries, rather than a “revenue-generation” initiative.
f) Seek experience and lessons from managers of existing programs
No matter how well it is planned and managed, running an ASE program is a learning experience. All successful programs have adapted to changing situations and all successful managers have modified elements of their programs that needed improvement.
g) Determine nature of violation and penalty
Depending on existing laws, ASE violations can either be considered “point” offenses that are punishable by fines and license sanctions or non-point offenses that are only punishable by fines. If possible, policies should be consistent among neighboring jurisdictions that use ASE to avoid public confusion.
h) Identify enforcement equipment alternatives
As identified in Q5.1, ASE systems have three basic components: a speed measuring component, a data processing and storage component, and an image capture component. In recent years, some jurisdictions have begun to supplement photographic evidence with a video record of speeding violations. Video resolution and frame rate are not currently at a level where video could replace photographs for driver and vehicle identification.
i) Identify requirements and resources needed for ASE program
The final step in the ASE planning phase is to identify the functional requirements, equipment requirements, and personnel requirements for the ASE program, as well as additional resources that will be needed to support the enforcement effort. Requirements should be defined in as much detail as possible, with prioritization according to level of need. Although some requirements might remain unknown until the final arrangements are made with the vendor, it is important to begin to identify requirements early to be able to effectively communicate needs to potential system vendors.
Prior to implementing speed cameras (or other automated enforcement program) the GRSF Guide for Determining Readiness for Speed cameras and other Automated Enforcement should be reviewed.
Appropriate site selection is essential to achieve the highest level of safety benefits and to ensure the public that safety is the top priority of speed enforcement. The highest priority enforcement sites should be located where there is the greatest risk for speeding-related crashes, injuries, and fatalities.
Crash risk can be determined from reliable data on crash history, crash patterns (e.g., seasonal or time of day) and other factors such as the percentage of vehicles that are speeding or traffic volume. Risk can also be high where there is a lack of supporting infrastructure for the type of road use (e.g., the presence of pedestrians, but poor infrastructure provision) and high vehicle speeds. It is generally unwise to select sites where speeding is common and risk is low because the public is likely to perceive these locations as “speed traps.” However, exceptions may be made in locations with many pedestrians and in neighborhoods where speeding adversely affects quality of life.
Citizen complaints can also help to identify locations with speeding-related safety problems. Responsiveness to citizen complaints is important because citizens may be the first to notice a developing safety problem and because speed enforcement is ultimately for the benefit of the (local) public.
A site should be defined either as one specific location or as a corridor with multiple enforceable locations. In general, defining a site as a corridor can be expected to result in a more widespread deterrent effect because enforcement locations are less predictable. Sites clustered in particular neighborhoods can provoke charges of biased operations or targeting of particular groups.
Other considerations might include:
School zones are frequently selected as locations for speed cameras and where this has occurred the public response has been positive. High-level support might make school zone enforcement a good way to introduce speed cameras in a jurisdiction.
Residential neighborhoods typically have low traffic volumes and low speed limits. Speed cameras should only be introduced at locations where speeding creates a safety problem or has a negative impact on quality of life, but within this constraint, public demand for speed management can influence site selection. It is important to have support from the residents of neighborhoods where speed cameras are used. School zones are one such example.
Major roads or arterials are often among the most dangerous roads in a jurisdiction, with high traffic volumes, high traffic speeds, and complex roadway geometries and traffic patterns. Speed cameras can have a significant impact on major roads, but factors such as multiple lanes of traffic and close proximity of vehicles can make it more difficult for speed cameras to single out speeding vehicles.
Roadwork zones often feature complex and transitory traffic patterns that increase the level of risk for road users and road workers. Voluntary compliance with reduced work zone speed limits is often low. Speed cameras may be especially helpful in work zones because they can be used in places where traditional enforcement methods are infeasible or hazardous.
For further information on speed camera operations, see this guidance, and to assess speed camera readiness, see here.
Establishing an effective speed camera program initially will require adequate funding, covering the costs of personnel, vehicles and other equipment, operating costs, and maintenance. Ensuring the program is cost-effective relies on how sustainably it was set up. The implementation and continuance of the speed camera enforcement program should not be dependent on grant funding, which is uncertain from year to year.
At the same time, it is very important how the speed camera enforcement program is communicated to the pubic: it should be presented as an initiative to increase safety in the community and not as a tool for revenue collection.
Most research demonstrates that the use of speed cameras generates substantial net benefits. It also shows that the ‘pay back’ period for this technology is fairly short. This is why it is vital to educate the public about how the revenue from such programs can be re-invested into further road safety programs.
Two key factors to be taken into consideration are: (i) focusing the enforcement at the most serious locations, and (ii) letting people know about the purpose of the program and the benefits of reducing speeding.
(i) Site selection
A variety of road types should be considered to ensure safety benefits are maximized in the jurisdiction, including:
→ School zones
→ Residential roads
→ Construction zones
→ Urban roads
→ Rural roads
After deciding on the road type, the next questions are:
→ Where are the crash locations that have the highest priority for speed enforcement?
→ Where are speed-related crashes occurring during daytime and at night?
→ At what locations are speeds dangerously high?
→ At what locations are citizens complaining about speeding and reckless driving?
In some instances, it might be more cost effective to have several camera sites with one camera rotating between them.
(ii) Raising awareness
It is well known that the speed enforcement program can be enhanced with the presence of a communication and marketing campaign (see Q7.1 to learn more on this topic).
For further information on speed camera operations, see this guidance, and to assess speed camera readiness, see here.
The automated speed enforcement program will be sustained over time if the law enforcement agency, partner organizations, and the community maintain the focus on traffic safety and speed enforcement. Within the law enforcement agency, conducting regular reviews at roll calls or special meetings and events will update officers on the program’s progress and remind personnel of the strategic plan. These steps will spotlight the program’s importance and help make speed enforcement an integral part of the agency’s culture.
Automated speed enforcement should be used to supplement, but not replace, other traffic law enforcement activities. It can only be used to observe speeding violations, so police officers must be active on roads to observe traffic for other violations. Traditional law enforcement can be used in conjunction with automated speed enforcement. Positioning a traffic enforcement officer at the same time and on the same road as a speed camera may lead to a more widespread deterrent effect. In addition, being stopped by a police officer may reduce a drivers’ speeding behavior, while drivers photographed by speed cameras may continue to drive at an unsafe speed. Another coordinated enforcement strategy is to alternate enforcement at a location between a speed camera and traditional law enforcement.
There is no single best method for enforcing speeds. Each jurisdiction needs to customize a combination of technologies and tactical methods to enforce speeds that work best for its community, which will include automated and physical enforcement.
For further information on speed camera operations, see this guidance, and to assess speed camera readiness, see here.
In most countries, automated speed enforcement equipment is purchased, owned, and operated by government organizations. Over the past two decades a variety of privatizations and public private partnerships (PPP) have been implemented in formerly government-owned or run activities, including traffic enforcement. The International Roads Federation (IRF) report “Public Private Partnerships in Traffic Enforcement” highlights the need to implement such an approach properly through a set of principles and good practices.
The IRF report suggests that an effective automated traffic enforcement PPP model needs several basic elements, including:
→ A study to identify high risk locations (intersections or road sections that have a history of injuries or fatalities). This is important because the key objective is to improve road safety at these sites. The study should also review other safety countermeasures that have been considered.
→ A private party (a supplier or a third party) who is willing to supply the safety cameras at no upfront charge to the public party, and provide a service to issue tickets and collect fines for traffic violations recorded by the safety cameras.
→ A contractual arrangement between the public and private party. This should facilitate the private party to recover its investment over time through camera revenue
→ An authorized official must verify the offense after viewing the recording of the incident before the ticket is issued.
→ The integrity of the entire enforcement system must be guaranteed to ensure public trust and optimize efficacy and efficiency. This can be done through the oversight of an independent third party who should also inspect, verify and calibrate each camera to confirm the intended measurements and performances. An independent party should also monitor, inspect and verify that the entire process conforms to the agreement.
→ A well-publicized campaign is essential that stresses the sole objective of the automated speed enforcement operation is for road safety improvement, and that any revenue above the expenses incurred will be reinvested in road safety related projects.
For further information on speed camera operations, see this guidance, and to assess speed camera readiness, see here.
The legislative framework in each country should specify how automated speed enforcement fine money is used. It is appropriate for these funds to be used to pay for the operation of the program. Funds in excess of these costs, if any, should be used for highway safety functions. This should be communicated to the public so automated enforcement is not seen as a tax feeding the general coffers.
In France, the government has been spending about EUR 100 million per year on investment and operational costs of speed cameras. When all cameras are operating it is anticipated that revenues will amount to around EUR 375 million per year. Typically funds from traffic fine revenue are reinvested in road safety improvements, such as road infrastructure improvements in addition to the building of hospitals and other health services. It is therefore crucial that there is transparent communication including to the public on the allocation of the revenues, confirming that these are mainly invested in road safety improvements. It is also interesting to note that reduced speeds due to the automated speed enforcement program led to petrol savings, which substantially reduced government profit from the tax on fuel products.
In Australia, great importance was placed on consultation with stakeholders, including communities before implementation of the program. This is because community adherence was seen as a key element of success. This includes ensuring that enforcement is not perceived as revenue raising but instead as a road safety activity.
The bottom line is that each annual report of the automated speed camera program should include a section on the costs and benefits of the program, listing the use of the program revenue, and communicated to citizens.
For further information, see this link, while for general information on speed management including enforcement, see here.
Existing research consistently shows that speed cameras are an effective intervention in reducing road traffic collisions and related casualties. The legislative framework should specify where automated enforcement fine money is spent. It is appropriate for these funds to be used to pay for the operation of the automated enforcement program.
Funds in excess of these costs, if any, should be used for highway safety functions. This should be communicated to the public so automated enforcement is not seen as a tax feeding the general coffers. Also, see content in Q5.11.
What is the evidence for the effectiveness of speed enforcement?
A TRL study (Elliott & Broughton, 2005) reviewed the literature on police enforcement and found for speed enforcement that speed cameras are more effective than physical policing methods in reducing speeds and road crashes; and that speed cameras are more effective in reducing road crashes within urban areas than on rural roads. The same study found that fixed speed cameras are more effective in reducing speeds and road crashes than mobile speed cameras.
Further detailed information on this issue for different technologies can be found in Q5.16. More general information on this topic can be found here.
Although all types of Automated Speed Enforcement (ASE) programs have the potential to reduce speeds and improve safety, the actual effectiveness of these systems is dependent upon actual implementation.
Overt (visible) enforcement provides some indication to road users that they are approaching an enforced location including fixed or temporary signage or road markings on the approach to the enforcement unit, or conspicuous vehicles or speed camera equipment (e.g. fixed camera housing). Covert (hidden) enforcement utilizes unmarked vehicles with no specific warning to drivers of an enforced location. There is good evidence that covert enforcement has a greater beneficial impact on driver behavior compared with overt enforcement (Keall, Povey, & Frith, 2001; 2002). Read more on this topic in FAQ5.14 and FAQ4.11.
All speed cameras accurately measure speed with camera functionality that collects evidence of the violating vehicle. There are generally two technologies:
RADAR Speed Cameras - A RADAR (Radio Detection And Ranging) speed camera measures the change in the frequency of returned radio waves (the Doppler effect) to measure vehicle speeds. The technology usually creates precise speed measurement when used correctly, and the equipment is commonly accessible.
LiDAR Speed Cameras - Modern LiDAR (Light Detection And Ranging), uses the returned time of pulsed laser light instead of radio waves (RADAR). This technology has become more popular in recent years due to its reliability. LiDAR systems are accurate, simple to deploy, mobile, and user-friendly.
Speed enforcement is most effective when it is unpredictable and difficult to avoid, when there is a mix of highly visible and less visible activities, and when it is continued over a longer period of time. Speed cameras can operate automatically or through manual control (either visibly or hidden in a car or van). Speed cameras can be used full-time at fixed locations (fixed cameras) or can be moved between different locations (mobile cameras).
Whether visible or invisible cameras should be implemented depends upon several considerations. For example, if speed control is required on a specific section of the road (e.g. because of an intersection or a nearby school) it is more effective to have a visible speed camera, preferably accompanied by a warning sign. On the other hand, hidden cameras, and in particular hidden mobile cameras make speed checks less predictable and so have more of a general deterrence effect. This is because drivers know that there is a chance of detection, but they do not know when and where exactly. There is generally very good compliance in specific locations where visible speed cameras are present. However, compliance is likely to be less when hidden cameras are used. Unfortunately, visible speed cameras may result in drivers slowing down at the camera location, but then they may be tempted to speed up again a few hundred meters after the camera.
Read more about this in a publication from the European Commission.
Point-to-point cameras, also referred to as time-over-distance systems, average speed camera systems or section control, differ from fixed, single-point systems in that they use pairs of cameras to measure vehicles’ average speeds along a clearly defined and accurately measured stretch of road, that could be anywhere between a few hundred meters and many kilometers in length. In the UK, the shortest measured site section is around 400 meters and the longest 46 kilometers. More than two sets of cameras can be used to enforce an even wider section of the road network.
Point-to-point cameras are often more effective in achieving compliance with the prevailing speed limit than spot speed cameras (which measure only the speed at a single point on the road, using either radar or inductive loops under the road surface) as a longer stretch of road can be enforced. This is why point-to-point cameras are often used in work zones or tunnels where speed compliance is especially important. For example, a point-to-point camera system has been successfully in operation within the Dublin Tunnel in Ireland since 2017 with the number of drivers complying with the 80 kph speed limit increasing from 45 percent to just under 90 percent.
The results from a study conducted by the RAC Foundation in the UK show that point-to-point cameras are effective in reducing collisions, especially those of a high severity. Even after allowing for the effects of trend and regression to the mean, highly significant reductions are noted. Read more about this study here.
The good news is that all automated speed camera systems are effective at reducing injury crashes when properly installed and operated, and there is no single best method for enforcing speeds. Research into the effects of speed cameras consistently shows positive results. An international review of studies reported that speed cameras produce a reduction of approximately 20% in injury crashes on road sections where cameras are used.
Although the level of effectiveness may vary for each technique, it is difficult to compare this effectiveness, as each method is used in different circumstances. For example, fixed speed cameras have a very localized direct impact, reducing crashes most at the location where they are installed. Mobile speed cameras potentially impact crashes to a lesser extent, but over a much wider area. Point to point camera systems are very effective over a longer extent of road network (see Q5.15).
Each jurisdiction needs to customize a combination of technologies and tactical methods to enforce speeds that works best for its community. It is possible to use a combination of different types of automated enforcement, but to achieve the broadest possible effect, mobile units should be the cornerstones of an automated speed enforcement program under most circumstances.
Read more on this topic in this publication from NHTSA, while to help prepare for speed camera implementation, read the document here. Also see the information provided in Q5.13 and Q5.14.
To avoid motorists speeding up above the speed limit upon passing the speed camera two effects must be considered : the ‘time halo effect’ and the ‘distance halo effect’.
‘Time halo effect’ is the length of time that the effects of enforcement on speed behavior continue after the enforcement operation has ended. With traditional policing methods, research by Elliott & Broughton (2005) found that “the time halo effects vary a lot, ranging from effects lasting one hour to up to eight weeks after the police activity has ceased”. In addition, short enforcement interventions (less than six days) at a specific location showed little or no time halo effect after the enforcement effort has ceased.
‘Distance halo effect’ can be interpreted as the distance over which the effects of an enforcement operation continue after a driver has passed the enforcement site (in this case, the speed camera). For distance halo, Elliott and Broughton (2005) concluded that:
The impacts of visible and stationary speed enforcement on driving speeds are halved for every 900 metres after the enforcement site;
The effects of visible speed enforcement on driving speeds typically last between 2.4 and 8 km;
Speed enforcement can have a much larger distance halo effects (e.g., up to 22 km), if visible and stationary enforcement is used randomly on a large part of the road network (see here for further details).
For further details from the European Commission, see here, while a study from the UK on the link between enforcement and safety outcomes can be found here.
To measure the impact of speed cameras on road safety some basic data about program operations should be recorded and analyzed.
This should include:
Speed data, which can give a general idea of the effectiveness that speed camera units have in lowering vehicle speeds when they are present. This data might include the current speed limit including the enforcement threshold (speed tolerance) as well as the percentage of drivers speeding above the speed limit. To evaluate the effectiveness of speed cameras the mean speed and the 50th and 85th percentile speeds before and after the installation of the camera units may be of interested.
Violation frequency data, which can help in estimating the number of violations that will need to be processed and also give an early indication if trends in violation frequencies are changing.
Crash statistics, which should also be monitored at speed camera sites and throughout the jurisdiction to continue to identify the highest priority sites for speed cameras. Particular attention should be given to crashes where speeding was a factor and where crashes were fatal or severe.
Further details on data requirements for speed management can be found in FAQ2.3 and FAQ2.17. For further information, please see the NHTSA Speed Camera Guidelines here.
6. Speed management through vehicle technology
Vehicle technology plays a significant role in speed control. Major advancements have been made in automotive technology that have greatly enhanced vehicle safety through speed management. Speedometers were the first devices installed in this regard, whereas modern vehicles are equipped with more advanced technology, such as Adaptive Cruise Control, Electronic Stability Control, and Intelligent Speed Adaptation.
Some of the primary devices, often tailored to vehicles to boost speed enforcement, are briefly presented below:
→ Speedometer: The speedometer, one of the first in-vehicle devices to track speed, is important for the driver to maintain the desired speed, particularly for speed limits.
→ Speed limiters (SL): Speed limiters, commonly known as Governors, are used for the setting of road speed in commercial vehicles. SL are pre-programmed to prevent a vehicle engine from exceeding a maximum speed. SL could be helpful in limiting bus and truck speeds, especially in rural areas where over-speed is most frequent due to lack of enforcement. Further information is provided in Q6.3.
→ Conventional Cruise Control (CCC): CCC is a technology that can help automatically maintain and regulate a vehicle’s speed as set by the driver. It responds by continually changing the fuel supply to sustain the speed generated by wind, rolling resistance or the gradient. It reduces driver workload as less concentration is required for speed control and maintaining the speed within the expected range.
→ Adaptive Cruise Control (ACC): ACC is a modern CCC version that utilizes radar or laser sensors for detecting and tracking vehicles in front and adjusting to their speed. In addition to choosing cruise speed, it allows drivers to change the time gap and headway in the travel lane with the front vehicle. Further information is provided in Q6.4.
→ Intelligent Speed Adaptation (ISA): ISA is a speed management device that utilizes cameras and/or an in built GPS map to determine the speed limit of the road to provide warnings and/or limit the speed of the vehicle if the speed limit has been exceeded. ISA is increasingly used as standard in new vehicles and will be mandatory in Europe from 2022. Further information is provided in Q6.2.
Click here to explore these technologies further.
Intelligent Speed Adaptation (sometimes Intelligent Speed Assistance, or ISA) is one of the most promising IT systems for its potential effect on safety. ISA is an intelligent speed control system utilizing data from the road environment and vehicle. The vehicle receives and responds to the desired or legal speed limit from the area. The system uses a digital in-vehicle road map to encode speed limits, together with a navigation system such as the Global Positioning System (GPS) satellite and/or traffic sign recognition. ISA could be three types in total: informative, voluntary supportive, and mandatory supportive.
Field and driving simulator experiments of ISA show positive effects on speed management and predict significant safety benefits. According to Várhelyi and Mäkinen (2001), ISA was found to be effective in reducing the speed in roads with 30-70kph speed limit. Carsten and Tate (2005) showed that mandatory use of supportive ISA could reduce the serious crashes up to 50%. The safety benefits of voluntary ISA are much smaller. It was demonstrated by Swedish and Dutch research that speeds were slower and more uniform when using ISA. In Britain, assessment of ISA system for trucks also provided positive evidence of safety benefits with respect to greater speed compliance.
Recently, ISA effectiveness was also assessed by The University of Adelaide Centre for Automotive Research based on real word crashes. It was found that ISA can result in substantial reductions in impact speed in a crash, and if all vehicles were fitted with ISA fatal and serious injuries would be reduced by 17.6% with limiting ISA, 8.1 to 12.3% with supportive ISA, and 5.1 to 9% with advisory ISA. The benefits and also the limitations of ISA are shown in the study “Intelligent Speed Adaptation (ISA): benefit analysis using EDR data from real world crashes”.
Some studies mention the negative side effects of ISA, but the scale and implications of these potential negative side effects are still limited. However, research has identified that the driver may become less vigilant, more confident/ frustrated or show compensation behavior in a few instances.
ISA is one of the vehicle safety technologies included in the EU’s new General Safety Regulation for motor vehicles (GSR) and will become mandatory for all new vehicles types as of 2022 and all new vehicles as of 2024.
You can find relevant information from the European Commission here. Other interesting resources includes WHO, ETSC and NCAP.
Speed limiters (SL), commonly known as speed governors, are pre-programmed devices that interfere with a vehicle engine to prevent it from exceeding a maximum speed. It has been found to be beneficial on trucks and buses for the setting of road speed. Since SL capability is standard, the cost of introducing SLs is negligible.
The effectiveness was broadly assessed by Hanowski, R. J. et al. (2012), who showed that SLs are effective in reducing speed-related crashes. UK Analysis found that the rate of crash involvement for SL trucks dropped by 26%. Australia estimated a crash reduction of 29% involving trucks in this case if SL regulations are in force.
SLs cannot fix speeding on roads with speed limits lower than the top speed the vehicle is set at, and the literature shows that travelling too fast for the conditions tends to be an issue in these circumstances. Traffic consequences have also been reported as a problem in some places, such as the United Kingdom, owing to the long-distance needed for one SL truck to pass another. However, the negative effects of the SLs tend to be greatly outweighed by the safety gains associated with the decrease in total speed of the SLs.
To know more about this click here.
Adaptive Cruise Control (ACC), a modern edition of Conventional Cruise Control, utilizes radar or laser sensors for detecting and tracking the speed of vehicles in front and adjusting speeds based on this. In addition to choosing cruise speed, it allows drivers to change the time gap and headway in the travel lane with the front vehicle.
ACC utilizes forward collision warning (FCW) system technology. This is an advanced safety technology that monitors the speed of a vehicle, the speed of the vehicle in front of it, and the distance between the vehicles. The FCW system will warn the driver of an impending crash if vehicles get too close because of the rear vehicle's speed. More than just warning, when available, the Autonomous emergency braking, known as AEB, engages the main braking system when it detects an imminent crash. The findings showed a 38 percent overall reduction in rear-end crashes for vehicles fitted with AEB compared to a comparison sample of similar vehicles. There was no statistical evidence of any difference in effect between urban (<= 60 km/h) and rural (>60 km/h) speed zones. More information about the AEB efficiency is available here.
Research has identified that, when applied , ACC will limit traffic speed variations. More uniform speeds have been found to reduce the likelihood of the crash.
Chira-Chavala and Yoo (1994) analyzed crash data and identified that ACC may be a potential countermeasure for 7.5 % of crashes. Research by Rudin-Brown and Parker (2004) also indicates, however, that drivers may become excessively dependent on ACC as they become used to its service, raising the risk of a crash.
Click here for further information.
There are various in-vehicle speed monitoring devices which are currently deployed in modern vehicles. Those devices record several parameters to improve safety. The available in-vehicle Speed Monitoring Systems are provided below.
→ Event data recorders (EDR): EDR, widely known as "black boxes" that record many parameters before, during and after a crash, including vehicle speed. According to the research of Lehmann et al 1998, and Toledo et al 2008 the adoption of EDR can trigger substantial changes in driver behavior, including reduced speed and lower crashes if the driver and employees are aware about the device installation.
→ Tachographs: This device tracks the speed, the overall distance travelled between the stops and the resting periods of a vehicle for the entire trip. Mechanical tachographs are commonly used in professional driving, particularly in heavy goods vehicles. They are used by the police and transport operators to monitor the amount of continuous driving and resting hours, as well as the maximum and average speed during a trip. Electronic tachographs are increasingly fitted on commercial vehicles voluntarily, which allow real-time speed monitoring, report service hours of drivers and other parameters, and track freight.
→ Speed monitoring devices: This system gathers information related to an insured risk, including distance driven, speed, and travel distribution by day and day of the week. Advanced speed monitoring system consist of GPS technology which assists to monitor vehicle speed by dynamic tracking. Advanced data recorders can continuously record speeds and link them to speed-limit databases, tracking speed in real time.
Please click here to explore these technologies further.
Currently the driver, not the car, is responsible for obeying speed limits at all times. ISA remains a driver assistance technology.
ISA limits the speed of the vehicle based on several inputs including speed limit sign recognition and on-board electronic maps of speed limits linked to Global Positioning Systems (GPS) when available.
Consequently, the accuracy of the system also depends on the quality of those inputs. Although the speed sign recognition technology is improving rapidly, detection of the current speed limit at a high level of accuracy including temporary speed limits, digital signs and overhead signs should be also considered. Similarly, ‘over-the-air’ updates of speed limit information stored in the car is currently possible, especially for the cars which in some regions must have the built-in communications technology required for the eCall system.
In conclusion, there are a limited number of cases when the car could incorrectly limit the speed both lower or higher than is permitted. In both cases, the driver would be able to override the system and would be responsible for ensuring that they do not exceed the speed limit.
You can find out more about the system here.
Yes, in some parts of the world. For example, most manufacturers already sell cars in Europe with various types of ISA.
More details on how the system works as well as a list of vehicles equipped with the system at this time in Europe can be found here. Obviously, the list is not exhaustive considering that the system is introduced by more and more manufacturers on new models.
Euro NCAP, the consumer safety rating organization in Europe, gives points for vehicles that include ISA and so it could be expected that there will be incentives for manufacturers to include this in all models in the near future. Other NCAP programs may be expected to follow given the benefit of this technology.
Yes, it appears that this technology has the potential to improve young driver safety, including through better choice of speed. A good example is the Young Drivers Telematics Trial (YDTT), launched in 2018 in New South Wales, Australia. The result of the YDTT suggests that telematics use has an overall positive impact on young driver behavior including reductions in speeding behavior as well as harsh braking and acceleration, and harsh cornering behavior.
The extent to which telematics use can positively impact young driver behavior depends on certain variables, such as the traffic environment and the driver’s socio-demographic characteristics and it is unclear as to whether the behavioral changes would be sustained over a longer period. The final report documents the key findings of the YDTT, based on the analysis of over 1.8m km (out of a total 4.1m km) of driving data recorded by young drivers from across NSW and it is available here.
Another case is the Volvo Care Key technology, aimed at reducing speeding deaths. The Care Key technology allows the vehicle owner to set the top speed of their vehicle before handing the car over to younger family members or less-experienced drivers. This is in addition to all-new Volvo models now being limited to 180 kph for all drivers – see here). Volvo isn't the first manufacturer to offer vehicle owners the option of limiting the top speed of their cars. Ford has offered a similar feature since 2015. Ford’s MyKey technology permits the limiting of the vehicle's top speed, as well as reduced maximum radio volume, disabling of the radio until seatbelts are fastened, and prevention of driver assistance and safety features from being deactivated. Additional information can be found here.
Yes, in some cases the ISA system will reduce speed when either the driver exceeds the current speed limit, or when the vehicle enters an area where the new speed limit is lower than the current vehicle speed. This response depends on the type of ISA (also see FAQ6.2).
For informative systems, when the vehicle encounters a lower speed limit it will display a visual warning to the driver only. It is then the driver’s responsibility to brake to reduce the speed appropriately. However, under the supportive and limiting version of ISA, if the driver does not apply the brakes the vehicle would slow down naturally to the new speed limit by reducing engine power unless overridden. This is the equivalent of the driver lifting his or her foot off the accelerator.
The driver may encounter automatic braking while using ISA if an automated emergency braking (AEB) or adaptive cruise control (ACC) system is also in operation on the vehicle.
You can find out more about the system here.
The levels of Vulnerable Road Users (VRU) road trauma greatly increases when the posted speed is beyond the threshold advised by the Safe System approach – read more about these thresholds here and in FAQ1.4. Read more about the relation between VRU trauma and speed in FAQ2.13.
According to the U.S. Department of Transportation, ITS solutions and technologies are becoming more and more prevalent, and there are several ITS categories that are used to enhance road safety. Find the report here. Among these categories, there are some safety features, such as Motorcycle Anti-lock Braking Systems (ABS), that could help motorcycle speed management by aiding motorcyclists maintain safe speed levels and avoid crashing at higher speeds.
Motorcycle Anti-lock Braking System (ABS)
ABS are safety systems that allow the wheels on a motorcycle to maintain tractive contact with the road surface according to rider inputs while braking, preventing the wheels from locking up (ceasing rotation) and avoiding uncontrolled skidding.
Motorcycle ABS, also known as Antilock Brakes, were introduced in the late 1980s to improve stability by maintaining wheel rotation during hard braking. While ABS has been shown to generally provide shorter stopping distances for both experienced and novice riders, ABS can also increase braking stability and therefore prevent the motorcyclist from falling to the ground.
Rigorous research has shown that Motorcycle ABS reduced emergency care visits by 47% (see here). The severity of the crashes that did occur was lower, which reduced the overall risk of sustaining impairing injuries, although leg injuries were not addressed to the same extent. It was also found that almost 90% of fatal crashes with ABS were upright. This result suggests that leg injuries can be addressed by motorcycle design. An example with a specific design (i.e., boxer-twin engine) was analyzed, showing that leg injuries were reduced by approximately 50%.
Read more about motorcycle ABS here and here.
In addition to motorcycle ABS, there are several complementary ITS and motorcycle safety features that could help motorcycle speed management such as adaptive front lighting and daytime running lights, collision warning and avoidance systems, curve speed warning and electronic stability technologies. It should be noted that not all these solutions are widely and readily available, and some are still in the development stage to suit motorcycle safety needs. Read more about these solutions here.
As stated by the Economic and Social Commission for Asia and the Pacific (ESCAP), “the trend in ITS services is for such entities as vehicles, pedestrians and traffic infrastructure to become ever more interconnected, with the express aim of preventing traffic accidents.”
There are several ITS and vehicle safety technologies that can help reduce vehicles’ speed to safer levels for pedestrians and cyclists.
Advanced emergency braking system (AEBS) as defined by UN ECE is a family of vehicle safety technologies that can help pedestrian and cyclist safety. AEBS can automatically detect an imminent forward collision and duly activate the brakes to avoid or mitigate the potential collision.
Autonomous emergency braking (AEB), which is mandatory in some countries, is an AEBS with three distinct characteristics:
Autonomy: the system is activated independently and based on the detection of imminent forward collisions.
Emergency: the system will assess the criticality of the situation and intervene only if a forward collision is imminent.
Prevention: AEBS prevents potential collision by activating the brakes.
AEB Pedestrian: Many vehicle manufacturers now offer autonomous emergency braking systems which can slow and then bring the car to a safe halt before a vulnerable road user – typically a pedestrian or a cyclist – is struck, or at least reduce the speed of the collision.
Click here for a general reference on vehicle technologies and speed management.
7. Speed management through road user communication, education and engagement
Education, training, communication and promotion campaigns are essential elements of a comprehensive speed management policy. They are clearly focused on achieving safe driver behavior and improved road safety outcomes. They make a contribution to the improvements that a comprehensive speed management approach can deliver and complement the specific measures taken including those related to safer infrastructure, clearer and more consistent signing, vehicle safety and enforcement.
Mass media campaigns, coupled with enforcement and educational activities can lead to greater overall effectiveness in reducing speeding. The content of the messages should be based on risk and consequences, as well as aligning with improved or expanded enforcement processes. If campaigns are used to complement the enforcement activities, this should also be evaluated, outlining how the campaign contributed to the overall reduction in speeding.
Commercial advertising can also be in conflict with road safety goals. Advertisement campaigns produced for car manufacturers often promote high performance and high speed as a positive value; a way to enjoy driving more.
The pros and cons of public awareness campaigns have been frequently studied. This report (see link here) provides new insights on how to maximize road safety campaigns’ effectiveness.
Several examples of awareness messages with respect to lower speeds (not solely focused on enforcement) can be found at these links from Australia, the UK and the USA.
Learn more about the effects of road safety campaigns from here. For campaigns focused on speeding, see here.
Education delivers knowledge and training delivers skill, however the evidence so far does not indicate how these influence drivers’ perceptions of risks and consequences. Studies of most post-license driver training programs have shown to be ineffective and sometimes harmful to road safety. One of the main reasons for this is that any benefits gained through this knowledge and skill are outweighed by a greater risk from overconfidence following the training.
The goal of community engagement is to develop and enhance their participation in road safety and decision-making and raise awareness within them of their own personal behavior in contributing towards improved road safety. The City of Surrey, Canada engaged the public in dialogue with respect to lowering speed limits through their website found here.
Community engagement is also important in that the local community is more likely to accept the change in speed limit and subsequent enforcement of this if they are made aware of the risks and benefits of speed effective speed management. There are also examples where decision makers have supported speed limit changes due to community pressure, and this comes from increased community engagement, including through the efforts of NGOs.
The role of the community in supporting speed enforcement can be described under three basic approaches, which range in terms of the extent to which they are able to support the traffic police, the level of commitment involved, and their independence.
a) CONSULTATION - is the logical starting point for improving collaboration between local residents and the police. Local residents can assist the traffic police by providing additional information on the location and circumstances of unreported crashes, as well as on locations where crashes are ‘waiting to happen’, and where offences such as illegal turns or speeding, are a problem.
b) VOLUNTEERS - Local residents interested in assisting the traffic police on a more regular basis can volunteer on such programs as traffic wardens and school patrol programs.
c) PARTNERSHIP INITIATIVES - Potential partners include:
→ Community members
→ Neighborhood or community association members
→ Local businesses, including the Chamber of Commerce
→ Local pedestrian, bicycle and safety advocates
→ Groups representing victims, including families of loved ones lost/injured
→ Groups representing people with disabilities.
As one example, Community Speedwatch enables trained volunteers to work within their community to carry out speed checks on their local streets. The aim of Community Speedwatch is to make drivers who speed through residential neighborhoods are aware of the impacts on local residents or the danger they pose to other road users and pedestrians. Road users who are speeding are sent a warning letter along with advice to help change their driving behavior. If it is done properly, Community Speedwatch can not only improve police legitimacy but actually make a positive difference to road safety.
A recent evaluation of the scheme in Sussex, UK, identified that over five years the percentage of people who reoffended dropped from 25 percent to six percent (see the evaluation here).
VicRoads has prepared a general guide for engaging the community and stakeholders in local road safety plans. It can be found here.
It is important to use a strong communications campaign including marketing and media to explain the philosophy and strategy behind a Speed Camera program. A speed camera program should be described as a tool that can enhance the capabilities of traffic law enforcement and that speed cameras will supplement rather than replace traffic stops by officers.
The public should also be made aware that speed cameras are used to improve safety, not to generate revenue or impose “big brother” surveillance. Saying this will not necessarily make it so in the eyes of the public, so it is important to explain how each element of the speed camera program puts safety first and how controls are in place to prevent misuse of the system. Engaging the media early in the process can help gain public support for the speed cameras, as the program develops. A comprehensive communications campaign is essential to maintain positive public relations and to ensure that the public understands how speed cameras work and why it will improve safety as a supplement to traditional enforcement. The campaign should begin in advance of the introduction of speed cameras, providing frequent updates throughout the planning and implementation stages. The two most important goals of the communications plan are to maximize public awareness and acceptance of the speed camera program. Data should be evaluated to identify at-risk drivers in the community. Special attention should focus on males and young drivers.
To achieve speeding deterrence, the public must be aware of the speed camera program and how it works. The public should be educated about the speeding problem and how it affects their community. Current efforts in traditional enforcement should be highlighted, including an explanation of how speed cameras will supplement the effort to make the community safer, decrease traffic congestion, and improve quality of life. An explanation of how the technology functions, successes in other communities, and how it is implemented should be included. The number of enforcement units in use, whether they are mobile or fixed, the types of sites that are enforceable, and the total number of enforceable sites should be explained. It is also possible to make public the specific locations of sites, though it would be unwise to reveal the schedule in advance of their deployment. Identifying all potential locations may have a positive effect on deterrence at problem locations if drivers know where enforcement is frequently located.
Revealing enforcement locations also contributes to the goal of program transparency and might appease some critics of the program, though public awareness of enforceable sites may reduce the general deterrent effect of speed cameras. It is also important to inform the public about the procedures for violation processing, payment, and adjudication. The public should be made aware of the penalties for speed camera violations and their rights and options if they receive a violation notice.
The State of Victoria promoted the use of camera technology through a comprehensive website located here.
The simple answer is no. Mass media advertising is often the most visible component of a campaign, however, to be effective, this must be combined with visible government and/or community support, particularly law enforcement. The effectiveness of publicity campaigns when they are combined with highly visible enforcement has led to substantial reductions in drunk driving in Australia and Europe.
For example, publicity about the number of deaths and injuries caused by speeding, combined with information about how lower speeds reduce the number of deaths and injuries, may change attitudes to speeding, or make lower speed limits and higher penalties for infringements more acceptable. While the presence of traffic law enforcement is essential, supporting campaigns are vital in elevating the profile of speeding as an issue which is legitimate for the police to pursue and to make drivers aware of the consequences of this activity.
Research in many countries has shown that a publicity campaign by itself has only a modest impact on attitudes and behavior. Campaigns work best when combined with other interventions, such as enforcement of traffic laws and regulations, or provision of other safety services and products. A “behavior change” campaign must include enforcement. Social media is most important in reaching younger people. It is important (and valuable) to use social media as a way to engage people in the campaign, rather than as a one-way communications channel. For example, you can encourage followers and partners to share, re-tweet and like your campaign messages and visual content like photos, infographics and film clips, to promote the campaign to a wider audience. You can also invite people to give their views on the campaign topic and feedback on how the event went, and post their own pictures and film clips.
For more information, you can consult this resource in addition to the the recently published GRSF guide for Road Safety Interventions: “Evidence of what works and what does not work”.
In the late 1960s & '70s, the Netherlands was far from being an acknowledged leader in pedestrian and cyclist safety as it is today. Road deaths numbered in the thousands, and as documented in Road deaths in the Netherlands, hit a ceiling well above 3,200 per year. Cyclists, pedestrians, and children paid most of the price.
This triggered the historic ‘Stop de Kindermoord’ (literally "Stop the Child Murder" in Dutch) grassroots movement in the Netherlands. The success of this movement turned Dutch government policy around and the country began to restrict motor vehicles in its towns and cities and direct its focus on growth towards walking and cycling.
Since then, a large number of grassroots advocacy groups, established on similar lifesaving agendas, have emerged around the world, some of which are focused on speed management.
20's Plenty for Us is a 'not for profit' initiative with 500 local groups campaigning to make cities, towns, and villages around the world better places to be. They campaign for a default speed of 20 mph (30 kph) on residential streets and in town and village centers, without the need for physical calming. Local circumstances may make a higher limit appropriate on some streets, providing that the needs of vulnerable road users have been fully considered.
Love 30 Canada is campaigning to make 30 kph the default speed limit for urban and residential streets. They state that no matter how safe vehicles, roads, and drivers are, all of these things will fail beyond certain speeds. Each road must be designed to have speeds that are in line with the injury potentials on each type of road in the event of a crash. The level of harm to vulnerable road users rises dramatically at speeds of higher than 30 kph, making this the sensible default limit for places where vehicles and people mix.
30please are campaigning for 30 kph speed limits to be the norm for neighborhood streets. They demand a strategy to create safe and connected walking and cycling network. They believe sharing existing streets by driving slowly on those that are not very important for cars is a sensible solution, not only from a cost perspective.
The success of a speed management program will depend overwhelmingly on winning the support of local politicians, community decision-makers and the community itself.
Speeding is a highly controversial issue, and any speed management activity, such as cameras, must be carefully managed to gain and maintain vital political and community support.
Even after producing evidence that speed and speeding are problematic and life-threatening, support from politicians for measures to reduce speeding must not be taken for granted. As speed management necessarily restricts driving behavior and driving choices, there is often a negative reaction by some politicians or key stakeholders when speed management interventions are introduced. Careful briefing of relevant political leaders is an important step in securing political will, not only for reducing speed limits but also especially for introducing automated enforcement.
Investing time and effort in involving politicians is most worthwhile, as is communicating with key stakeholders about the intentions and goals of the program. Stakeholder involvement is best developed through a working group that supports the development and implementation of a speed management strategy. From the first concept of considering an automated speed enforcement program, politicians, government agency stakeholders or the people that will be the main implementation partners of the strategy should be consulted and engaged.
For further information see here.
Some of the most impactful low-cost opportunities for communication and awareness include the following:
→ Traffic Safety Committee – The formation of a local Traffic Safety Committee can increase community support for speed enforcement efforts.
→ Local radio, including public service announcements, traffic reporting, and paid media – Use this platform to establish a recognized presence, answer residents’ questions, and relate recent or upcoming activities. For example, officers may participate in the morning traffic report on various local radio shows, giving residents an opportunity to speak directly with law enforcement and relate issues that are important to them.
→ Local newspapers and newsletters – Provide press releases on activities and outcomes of the program on a regular basis. Raise the reporters’ interest by encouraging them to ride along and witness the speed enforcement activity in action.
→ Fliers and brochures – These may be used to relate factual information and data, describe activities, and detail the goals and objectives of the program. Fliers and brochures may be handed out in various public venues or mailed to community residents.
→ Informational handouts provided by law enforcement personnel – with information about the risks of speeding and the speed enforcement program may serve as educational material and be distributed while conducting speed enforcement activities.
→ Web sites – The community and the law enforcement agency Web sites are useful venues to announce program activities, present answers to frequently asked questions, present findings and report program progress, and provide contact information.
→ Fixed billboards, variable message signs (VMS), and speed reader boards – These may be used to publicize speed-related messages and eye-catching slogans. They may be located in construction zones and school zones, along highways and arterial roadways, and in residential communities.
→ School activities and local grassroots events – These venues are helpful for face-to-face meetings with community residents. For example, a booth on the speed enforcement program might be set up at a community health fair or on back-to-school night at the local high school,
→ Social media is most important in reaching younger people. It is important (and valuable) to use social media as a way to engage people in the campaign, rather than as a one-way communications channel. For example, you can encourage followers and partners to share, re-tweet and like your campaign messages and visual content like photos, infographics and film clips, to promote the campaign to a wider audience. You can also invite people to give their views on the campaign topic and feedback on how the event went, and post their own pictures and film clips.
However, as indicated in other FAQs in this section (e.g. FAQ7.1) communications and awareness raising need to occur as part of a broader strategy (e.g. involving enforcement activity) to be most effective. When conducted in isolation, these programs typically have very limited or even no benefit. For more information on effectiveness of communications and awareness raising see here.
8. Speed management fallacies / myth busting
Speeding and travelling too fast for the conditions are the biggest cause of death and serious injury on our roads. This is perhaps also the area where we have the clearest evidence base regarding this risk relationship. Much of the published research indicates that speed contributes to around 30% of deaths, but it is also frequently recognized that this is likely to be an under-estimate. We know this because when appropriate speed management is put in place, we see reductions of 60% or even greater in deaths and serious injuries.
The good news is that even small reductions in speed can have a substantial reduction in fatal and serious crash outcomes. As outlined in Q1.5, just a 1% reduction in speed can produce a 4% reduction in deaths on the road.
For further information on the link between speed and safety outcomes, see information from the WHO here and here; the European Commission here, and ITF here.
There is good news: Generally speaking, lower speeds have actually positive effects on congestion. Still, fighting congestion effectively and sustainably is a very difficult task as drivers’ travel patterns are often repetitive and added capacities are normally rapidly consumed by induced demand and population growth.
There are two types of traffic congestion: recurring and non-recurring. About half of traffic congestion is non-recurring and caused by ‘temporary disruptions’ in travel, e.g. due to bad weather, road closures, vehicle crashes or break-downs. Higher speeds will lead to more crashes and thus increase non-recurring congestion.
Recurring congestion happens in regular intervals (rush hours) and is due to a lack of capacity on the road — or in other words, there are more vehicles travelling at a given time than can physically fit. When this happens, vehicles are likely to already be travelling well below the speed limit, so a reduction in speed limit is not likely to affect speed during congested hours.
In busy urban environments the average journey speeds are often already considerably lower than the set speed limits. Travel time is mostly influenced by frequent stopping or slowing down, e.g. at intersections or at railway crossings. Drivers assume that driving faster will reduce overall travel time, which is not true in urban environments. Traffic moves most smoothly at a speed of 20-30 kph. The following-distance between cars may be shorter at lower speeds, but it still allows traffic from side streets to filter in and encourages the continuous movement of traffic. A speed of 30 kph allows the road system to smoothly accommodate the maximum number of cars (more cars than at higher speeds). Thus, lower speed limits generally mean less recurring congestion and faster overall travelling time for all. In a world where time is money, this is a significant advantage.
Furthermore, traffic congestion in urban areas is a major consideration for assessing various modes of transport. Lowering speed limits will encourage more walking and cycling, and – given that an adequate walking and cycling infrastructure is provided – this shift will free up capacity to your roads, reduce the strain on public transport and has positive effects for the environment.
You want to know more? Learn from studies published by SWOV and Monash University.
From a road safety perspective increasing traffic speeds is generally is a very dangerous idea (unless the infrastructure fully supports the change). Even rather small increases in speed dramatically raise the number of people killed or seriously injured in road crashes.
High speeds reduce the possibility for the drivers to respond in time when necessary. People need time to process information, to decide whether to react, and finally, to execute a reaction. At higher speeds the distance covered in this period as well as the distance between starting to brake and a complete stand still are longer. Therefore, the possibility to avoid a crash becomes smaller as speed increases.
Another very important aspect is that more kinetic energy must be absorbed during a high-speed impact. The kinetic energy during a crash greatly increases due to velocity rather than mass and consequently, small increases in vehicle speed will result in major increases in the risk of injury.
Thus, higher speeds not only increase the likelihood of crashes (see Question 1.6) but also their severity. Sound scientific relationships have been established between speed and crash risk: The general relationship is valid for all speeds and all roads, but the rate of increase in crash risk varies with initial speed level and road type.
Furthermore, large speed differences between different types of vehicles – for example between faster cars and slower lorries on an expressway – also increase the likelihood of a crash. Higher speed variance results in less predictability, more encounters and more overtaking maneuvers. The probability of a rear-end crash with a slower car in front, or a head-on crash when overtaking a slower car increase. Therefore, when speed differences increase, the crash risk increases as well.
The good news is that even a small reduction in the mean speed reduces the number of crashes and the severity of injuries. In this context the more severe crashes get influenced the most.
The following tables show the impact of a 1 kph and 2 kph average speed reduction, respectively, on the severity of crashes for roads with different reference speeds. The reference speed is the ‘original speed’ driven on a road before a change in speed.
The tables clearly show the importance of even small reductions in average speed on the severity of crashes. On slower roads, typically in urban areas, the impact of a small speed reduction is generally bigger. However, the relationship between speed and crashes on a particular road will also depend on other factors such as traffic characteristics and road user behavior (drink-driving, seat belt wearing etc.).
You want to know more? Click here.
Often a traffic sign might not be enough to convince the road users to actually drive at or below the posted limit. It is often the case that drivers do not respect these limits – despite being aware of them – mainly because for the drivers seemingly identical roads have different limits.
There are many different ways to encourage people to drive at lower speeds, but evidence shows that self-enforcing speed limits are the most successful way to reduce speeds. A self-enforcing speed limit means that people are more likely to drive within the signed speed limit because they feel it's the easiest and safest speed to drive along that road. This is generally because of the way the road looks and has been designed. Engineering treatments have to be applied in addition to the speed signs to encourage – or force – the drivers to drive more slowly. A wide range of engineering solutions (see question 3.1) are available that have the effect of making it impossible or uncomfortable to drive in excess of the legal or recommended speed. But even in those cases where the speed sign is the only measure there is at least some good news: A new (lower) posted speed limit usually leads to at least some reduction in speed (typically around 3 kph for every 10 kph reduction in speed limit) – and even these small reductions in speed equate to substantive safety benefits (learn more in question 1.9).
You want to know more? Visit this website or look here for the effects of lowering default speed limits on road safety.
A lower speed limit may indeed impact the economy, but in a positive way. Drivers often assume that the faster they drive, the quicker they reach their destination. However, the cost of this assumption is high to the driver, to the driver’s family, to the insurance companies, government agencies and hospitals involved in caring for the trauma victims. The WHO Global Status Report on road safety (2018) confirms that the most impacted age category from road trauma is between 5 to 29 years old. Losing young people of working age impacts the economy. Costs related to injury and loss of life from traffic crashes as a result of excessive speed include the following:
→ Medical costs: money hospitals need to pay to treat injuries
→ Productivity loss: production loss can be calculated as loss of hours worked
→ Property damage: vehicle repair costs
→ Settlement costs: insurance or third-party costs
→ Congestion costs when a crash occur.
The opposite is also true. High speeds may have a positive impact on economy. High function roads, such as motorways and freeways, with few access points, moving a high number of people and goods, connecting across multiple cities, can have a higher posted speed limit. In such circumstances, the infrastructure measures will need to be supportive of high speeds so that where a crash occurs it shall not result in a fatality or serious injury.
Individual and collective risk at high speeds are different. At an individual level, the risk of being involved in a crash resulting in a fatality or serious injury is relatively small. Collectively, at a community level, the risk of excessive speed is well documented as being a major contributor factor to road trauma. Therefore, balancing the individual and the needs of a community as a whole is a challenging task and a difficult argument from an economic perspective.
Learn more about topic from Australian examples, or from a World Bank study on the High Toll of Road Traffic Injuries.
Many evaluation studies clearly show that speed humps and rumble strips produce positive road safety benefits. Both elements are often used as part of a broader area-wide speed management approach.
Transverse rumble strips, which are laid across the road, can alert drivers to hazards ahead (e.g., intersections, bends, or areas with pedestrian activity), thus slowing them down. They may also be used as part of a gateway treatment at the entrance into a town or village to make drivers aware of the fact that they are about to enter a built-up area and decrease their speed accordingly.
Longitudinal rumble strips, which are laid in the direction of travel either on the centerline or the edge line, can assist vehicles in keeping within their lane and may also be used to optically narrow the road and thus encourage drivers to slow down. Rumble strips do indeed induce higher levels of noise as vehicles pass over the strips. Thus, rumble strips are normally not used in residential areas.
Speed humps are very effective in slowing drivers down, especially in urban areas and locations with pedestrian traffic. If carefully designed and placed with the correct height, ramp profile, and width they result in minimal disruption for residents in terms of noise. It is essential that speed humps be well marked and signed in advance so road users are aware of their presence and prepared to slow to an appropriate speed. Lack of appropriate warning, especially in higher-speed environments, can create a road hazard, leading to issues such as instability of vehicles (especially motorcycles).
For further information, see here for information on rumble strips, and here (see Chapter 4) for information on speed humps.
Speed is a major contributing factor in serious road trauma, globally – see FAQ 1.9 for more information.
But what is the origin of this myth about “bad drivers”? There are two potential answers: 1) the conventional notion about road trauma causation, and 2) our innate biases and distorted individual risk perceptions. Let’s look at these and investigate their validity.
Road trauma causation – the conventional notion
Since the 1970’s, human error has consistently been considered as the major causal factor in a high proportion of road crashes and injuries (Salmon et al., 2005). Recent research claims that the driver error contributes to as much as 75% of all road crashes.
Relying on this, some members of the public and professional community argue that the focus on ‘Speed Management’ is misplaced and should be put into educating ‘bad drivers.’
While it is possible that the application of error management techniques and human factors could enhance road safety, it is proven that:
→ Speeding is a key driver risky behavior causing road crashes and injuries, and needs to be effectively managed (see FAQ 1.7 for more information)
→ No matter what causes a crash, higher speeds mean that more crash forces and energies are there to be absorbed, potentially, by human beings involved
→ Even experienced drivers can make mistakes, and this doesn’t make them bad drivers. This is just human nature. But speed is crucial when a mistake occurs, as it can make the difference between a minor injury, or a severe crash outcome (see FAQ 1.4)
Our innate biases and distorted individual risk perception
Self-enhancement bias: Human beings tend to describe themselves more positively than than the average population. For example, around 88% of American drivers consider themselves to be above average at driving (Roy and Liersch, 2013) which is simply not possible.
Distorted individual risk perception: Only one in fifty people (2%) report to have been involved in a crash in the last five years where someone was hospitalized (Road Safety Monitor, 2019). This percentage is even less for speeding-related injuries.
The combination of ‘self-enhancement bias’ and ‘distorted individual risk perception’ means that some members of the public are likely to believe that ‘bad drivers’ are the issue and not speed, or, at least, ‘speed management’ should not apply to ‘them.’
While more research is warranted, the existing research and surveys show that both ‘self-enhancement bias’ and ‘distorted individual risk perception’ are stronger for men than for women.
In summary, these are the key points to debunk this myth:
→ Speed is a major contributing factor to road crashes and consequent road trauma
→ No matter what causes a crash, higher speed result in more road trauma and more severe ones
→ As human beings, we are likely to overestimate our driving skills – the Safe System approach states that we all are humans and will make mistakes no matter how perfect we or the system are
→ We are very bad at working with low probabilities such as our individual crash or injury risk – however, when added together, these low probabilities generate huge social, human, public health, and economic consequences.
Some of the best speed management measures can be challenging and complex. While these measures are shown to work in some jurisdictions, any jurisdiction newly adopting them potentially needs to carry out organizational, cultural or at the very least technical change management. We all know change management can be a challenge.
However, saving lives and preventing serious injuries are worth the effort. Therefore, the commonly raised excuse that “Things are different here” is just not acceptable or productive.
But why is this a myth and not true at all?
Firstly, it is highly likely that the road transport system in your jurisdiction is fairly similar to that of advanced road safety countries.
At the very basic level, the transport system is composed of roads, assets, vehicles and people. More and more, the design standards and guidelines managing roads, assets and vehicles are converging, globally. The advent of international initiatives such as the Global NCAP and Global Designing Cities show that the fundamental principles are fairly similar, if not identical, everywhere.
Secondly when it comes to road users, it is argued that the human body and our biomechanics are not vastly dissimilar across the globe. Furthermore, the laws of physics apply universally and no matter where you are the survivable speeds (See FAQ 1.4) are fundamentally the same. While there is cultural and behavioural diversity, which is indeed refreshing, these do not mean that our basic human aspirations to live a long and healthy life are different.
Thirdly, there is a long history of initially resisted road safety measures that later proved to not only work, but also become a source of cultural pride.
In the late 1960's & '70's, the Netherlands was far from the pedestrian and cyclist epicentre it is today. Road deaths numbered in the thousands, and cyclists, pedestrians, and children paid most of the price. This triggered the historic ‘Stop de Kindermoord’ (literally "Stop the Child Murder" in Dutch) grassroot movement in the Netherlands. The movement initiated such vast systemic changes in the Netherlands that the country now boasts one of the best national walking and cycling networks, globally.
Another interesting story is the development of modern roundabouts. Widespread use of the modern roundabout began when the UK's Transport Research Laboratory engineers re-engineered and standardized circular intersections during the 1960s. While initially resisted and denigrated, as being ‘so different and not fitting our transport system,’ modern roundabout took off in France and Norway, in the 1970s, in the Netherlands, other parts of Europe and parts of Asia in the 1980s, and in the United States in the 1990s. Now modern roundabouts are not questioned and dismissed off-handedly.
Fourthly, there is significant experience in LMICs of successful application of speed management measures.
The World Bank’s report on ‘Road safety interventions: evidence of what works and what does not work’ offers a range of recommendations with a focus on interventions in LMICs, although the information may also be of relevance to all countries.
On the top of specific speed-related interventions, many safe road interventions are recommended for adoption, including integrated public transport, roadside and central barrier systems, medians, infrastructure to support appropriate operational speed for road users, roundabouts, grade separation and interventions to reduce exposure to risk at intersections, pedestrian footpaths and crossings, separated bicycle and motorcycle facilities, and traffic signs and line marking (including audio-tactile line marking). Some of these are highly effective, with up to a 70 or 80 percent reduction in fatalities and severe injuries (for example, safety barriers and roundabouts).
Finally, as adopted and emphasized by the United Nations and other global organizations, the vision to eliminate fatal and serious injuries on our roads goes beyond cultures and borders. No one should be killed or seriously injured on the road, and speed management is a proven preventive measure.
Time savings from speeding are mostly irrelevant on our daily trips. Our average car journey is less than 20 km per trip, and a World Bank study on mobility and congestion in over 150 cities in India shows a mean trip length of even less than 10 km per trip.
Travelling 5 kph over the speed limit in a 50 kph road on a 10 km journey will save about 1 minute of travel time. That is without considering delays due to congestion or stopping at traffic signals.
In busy urban environments the average journey speeds are often already considerably lower than the set speed limits. Travel time is mostly influenced by frequent stopping or slowing down, for example at intersections or at railway crossings. Drivers assume that driving faster will reduce overall travel time, which is often not true in urban environments. Traffic moves most smoothly at a speed of around 30 kph. At lower speeds the following distance between cars is shorter. Still, lower speeds allow traffic from side streets to filter in. This encourages the continuous movement of traffic.
At a speed of 30 kph, the road can accommodate the maximum number of cars (more cars than at higher speeds). Thus, lower speed limits generally mean less congestion and faster overall travelling time for all.
Also in rural areas time savings are only significant over very long distances. For example, raising the speed limit from 100 kph to 110 kph will save a little over 5 minutes if you are travelling 100 km – always assuming there are no other delays at all.
Lower speed limits may even reduce travel times by minimizing flow breakdown in some instances. Flow breakdown is a disruption to the steady flow of vehicles at uniform speed. It occurs when traffic volumes are close to the capacity of the road and any erratic or unexpected driving maneuvers, such as lane changing or sudden breaking, lead to stop start driving conditions. Reduced speed limits nearing these peak times have been found to both improve safety outcomes as well as improve traffic flow, thereby reducing journey time.
Nonetheless, any potential benefits can be made irrelevant when considering the increased crash risk and the monetary and social costs to the drivers and their families.
Learn more about this topic from the European Commission.