Abstract
A policy aimed at the traffic safety of pedestrians, cyclists and moped riders requires safety and exposure data. Traffic safety can best be measured in terms of accidents of the resulting damage. But, for various reasons, there is a continuous search for alternative data on conflicts, feelings of unsafety, and behaviour. The role of the alternative data is shortly discussed. Very often accident figures are related to exposure data. The data in use vary widely. Attention is drawn to the distinction between exposure data for safety policy and for research in accident causation or countermeasure evaluation. The use of exposure data for research purposes is discussed in detail.