Available exposure measures

Exposure measures can roughly be classified into two groups.

• Traffic estimates: road length, vehicle kilometres, fuel consumption, vehicle fleet
• Persons at risk estimates: person kilometres, population, number of trips, time in traffic, driver population

This categorisation is somewhat arbitrary and some measures can well be considered within the other category. For instance, often person kilometres are preferred over vehicle kilometres when fatalities are to be compared, because differences in vehicle occupancy rates may be captured by person kilometres (and not by vehicle kilometres). However, when the subject of a study is the occupancy rate, a comparison based on vehicle kilometres may be more reasonable.

A distinction can be made between indicators that are generally available in Europe and indicators that are not. The generally available indicators are (1) population, (2) vehicle fleet, (3) road length, (4) fuel consumption, (5) driver kilometres and (6) vehicle kilometres. With the exception of fuel consumption, these generally available indicators are compatible with CARE (Community Road Accidents Database) and are usable for EU road safety risk comparisons.

The indicator "fuel consumption" is not compatible with CARE. Also, some indicators are at best partially available: person kilometres, number of trips, and time in traffic. This does not mean that these indicators are useless. They can still provide valuable information on national or small-scale international level. For European wide comparison these indicators are not yet suitable for usage in the common framework.

A first classification of the EU member states on availability, compatibility and usability of exposure and risk data.