After successfully introducing projects to reduce traffic accident deaths, the European Union focuses on lowering the seriously injured as defined by the Abbreviated Injury Scale (AIS). We used in-depth crash investigation data for injury severity projection to get MAIS3+ (Maximum AIS) injury severity distribution information for a national data set.

In contrast to the projection method by weighting, the approach presented here maps the distribution of interest, i.e., the distribution of a particular variable, from the in-depth study to the national level. The scheme works by transferring conditional probabilities—estimated using the in-depth survey—to the national level and using these conditional probabilities to supplement the distribution information from the national database. Even though the enhanced national data set provides only injury severity distribution information, it can be used to analyse the temporal stability of the crash environment at different injury severity levels.

As an application of the method, we added MAIS2+, 3+, and 4+ injury severity distribution information, using the German in-depth Accident Study (GIDAS) information, to the German national crash data set and investigated the shift in injury severity over the crash years. Each new crash test standard shows a statistically significant injury severity reduction.