Chapter 5: Speeds (task 2)

Deliverable D3.1 of the EU FP6 project SafetyNet
Verbeke, T.; Goldenbeld, Ch.; Arsenio, E.

Road safety can be assessed in terms of the social costs of crashes and injuries. However, simply counting crashes or injuries is an imperfect indicator of the level of road safety. When crashes occur it is the “worst case scenario” of insecure operational conditions of road traffic. Work Package 3 of SafetyNet deals with Safety Performance Indicators (SPIs). A Safety Performance Indicator is any variable, which is used in addition to the figures of crashes or injuries to measure changes in the operational conditions of road traffic.

SPIs can give a more complete picture of the level of road safety and can detect the emergence of problems at an early stage, before these problems result in crashes. They use qualitative and quantitative information to help determine a road safety programmes’ success in achieving its objectives.


One of the main goals of SafetyNet WP3 is to develop a uniform methodology for measuring a coherent set of safety performance indicators in each of the 25 Member States and some non-EU Members. This report provides the first ideas from the WP3 team on this subject.

The SafetyNet team will move on to the other goals (offering technical assistance to some Member States that fail in producing the SPI data according to the developed uniform methodology & collecting current data on SPIs that meet the standards of the uniform methodology) at a later stage in the project.

Research areas

Work Package 3 of SafetyNet investigates SPIs in seven different road safety areas.

  1. Alcohol & Drug use
  2. Speeds
  3. Protective systems
  4. Daytime Running Lights
  5. Vehicles
  6. Roads
  7. Trauma management

State of the art report

This report starts off with a description of the general methodology. Then, the report describes the state of the art in the seven research areas. Firstly, the theoretical backgrounds of each research area are given. Secondly, the first results from the questionnaire (that was sent to 27 countries: the 25 EU Member States, plus Switzerland and Norway) are presented. And thirdly, the first ideas on the details of the SPIs that could be used in the future are described.

Summary Task 2: Speeds (Chapter 5)

Driving speed is an important factor in road safety. Firstly, driving speed is directly related to crash severity. Secondly, driving speed is related to the risk of getting involved in a traffic crash. Thirdly, crash rate is not only related to absolute speed, but also to speed dispersion.

The collection of speed data is often initiated by other motives than road safety alone such as traffic management and planning. It is clear that collection of speed data can help decision makers in the field of road safety to monitor safety interventions on specific road types and to make specific comparisons to study factors relevant to safety.

From the 27 countries, 17 countries responded to the questionnaire, and from these 10 provided data to all items required. This probably indicates that information about speed data is not easily accessible at a centralized source. Considering the desired properties of the speed SPI, we proposed a central tendency measure of the data and another considering its variability. The use of standardized average and/or median speed and absolute deviation will need further testing and validation across the set of countries, once the data is available, depending on levels of disaggregation and possible exposure variables. The issue of comparability may imply further adjustments in the suggested indicators, and the weighing procedures shall be validated.

Comparative assessment of road safety in a European countries and regions relies on a unified methodology for the measure of exposure, i.e. for the vehicle kilometres. The concept of speed SPIs has been inspired by the same philosophy and therefore shares the dependence on a valid and reliable methodology for exposure measurement.

Published in
State of the art Report on Road Safety Performance Indicators
SWOV (ed.)
European Commission, Brussels

SWOV publication

This is a publication by SWOV, or that SWOV has contributed to.