In the field of traffic safety it is essential that estimation of crash severity from real world accidents can be made with sufficient precision. Systematic as well as random errors in crash severity estimation together with other types of errors in the response of the accident forces makes the possibility to draw conclusions from accident data limited. It is therefore important to reduce different kinds of errors. In this paper a crash severity indicator which can be mounted into cars is presented. The indicator is a low cost mechanical device that can measure the deceleration in an accident, and under some conditions, also the velocity change (delta-v). The theoretical background is described as well as the results of some full-scale barrier tests with severity indicators mounted into the test cars.

It is concluded that the severity indicator can give a fairly high precision and together with other types of data collected will give valuable information for a low cost. The indicator is already mounted into rearward- facing child restraints used among the public.