Speed Survey Tool (Time-Based)

Knowing the speed of vehicles at a location is very important for making speed management decisions, including selection of appropriate road safety initiatives. The spot speed is defined as the instantaneous speed of a vehicle at a certain point in time or a specific location.

Spot speed measurements are used to assess free-flow speeds on a representative sample of vehicles on urban or rural roads. The free-flow speed is a driver’s 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).

Speed collected from a number of different vehicles provides a useful picture regarding road user behavior, and can be used for a variety of purposes. This includes monitoring change in vehicle speeds over time (including against speed targets), intervention selection and evaluations following the implementation of speed-related initiatives.

GRSF has created two Excel-based speed survey tools to help users record and analyze data at spot locations. The "speed-based" version of the tool can be used when a speed measurement device, such as a radar or laser, is available. This "time-based" version of the speed survey tool can be used even when this equipment is not available -- in this case, the assessment can be undertaken using a stopwatch to measure the time it take a vehicle to travel between two points.

Usage instructions are provided within the tool. We hope that it will be useful to practitioners and decision makers, and that it will encourage the greater collection of speed-related data to help in road safety decision making.