Report numberRA-2006-94
TitleFeasibility study for the correction of the accident figures
SubtitleFinal report
AuthorsPascal Lammar
Published byPolicy Research Centre for Traffic Safety 2002-2006
Number of pages122
Document languageDutch
Work packageOther: Knowledge traffic unsafety

This study clearly indicates the extent of the problem of underreporting, as well on the national as on the international level. This underreporting is closely linked with the registration procedure. This registration procedure as well as the different factors that are contributing to this underreporting are discussed. Next to these factors misclassification can also make the situation more complicated. 

Various information sources are being used abroad to get an idea of the extent of underreporting. Taking into account these international initiatives and results it was investigated which Belgian secondary information sources are useful to this end. Following secondary information sources were identified: medical files (hospitals, ambulance, medical emergency services (MUG), emergency call services, general practitioners), insurance companies, national health service, surveys and local police figures. Next to a discussion of the different secondary information sources, the use of injury piramids and the most important results of national and international studies concerning reporting rates are discussed.


The police data are quite reliable for traffic deaths provided that a good communication procedure is established between police services and the hospitals concerning traffic victims dying in the hospital within 30 days after the accident.


The Minimal Clinical Data (hospital admission data) are, at present, the best source to get an idea of the number of seriously injured traffic victims, on condition that the external cause of injury codes are correctly used and always applied.


The periodical Health interview surveys generate information about the number of traffic accidents among the general population and are currently the best information source for the total number of traffic victims.  However, the sample is too small to calculate detailed correction factors (e.g. for age and means of transport).


Using the most appropriate Belgian information sources, an estimation of the ‘real’ number of traffic deaths, ‘real’ number of seriously injured traffic victims, ‘real’ number of slightly injured traffic victims, ‘real’ total number of traffic victims and number of damage-only accidents was made. The correction factors were calculated based on the following reporting rates: 92% for traffic deaths, 48% for seriously injured traffic victims, 35.6% (Belgium) and 31.7% (Flanders) for the number of traffic victims (without deaths). Out of these figures following reporting rates were calculated for slightly injured traffic victims: 34.5% (Belgium) and 30.4% (Flanders), and for the total number of traffic victims (including traffic deaths): 35.9% (Belgium) and 31.9% (Flanders).

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The Policy Research Centre for Traffic Safety carries out policy relevant scientific research under the authority of the Flemish Government. The Centre is the result of a

cooperation between Hasselt University, KU Leuven and VITO, the Flemish Institute for Technological Research.


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