The Swiss federal road accident statistics are based on accidents reported by police authorities. It comprises accidents that result in injury or death on public roads and places, involving at least one vehicle. Every accident recorded by the police has to be reported to the federal office of statistics. Although every accident with 'damage to persons' has to be reported to the police by law, for different reasons not all of them are reported. In fact, there is a substantial underreporting of road traffic casualties. In addition the statistics might be biased by the fact that the injury severities are estimated by policemen and not by professionals. Additional source of bias might be the fact that a certain part of the fatal road accidents are actually not accidents but suicides.

In order that in the future preferably all accidents with injured persons can be registered without the mentioned biases, the police reported accident data should be complemented by medical data of hospitals, medical practitioners and accident insurence agencies.

The resulting complemented and corrected accident data base would then allow the planning of more effective prevention measures. As the data base would be updated yearly, it could also be used for checking the performance of realised measures.