The Operational Committee of the International Road and Traffic Accident Database (IRTAD) has regularly discussed the content of the data base in order to improve and increase its usage. The aggregated data base of annual accident data from the member countries is one-dimensional. In many cases, the national statistics are distributed in at least two dimensions, for example fatalities for different age groups or road types distributed among different accident types. This kind of information is not available in IRTAD. This report reflects to some extent the discussions concerning different proposals and is based on two questionnaires to the members of the operational committee. One questionnaire concerns the methods used in different countries to collect national exposure data and the other concerns killed and injured for different road user groups in different countries from accident statistics and exposure in person kilometrage for the same road user groups. Most countries have various national traffic counting systems, which are used more or less regularly in order to estimate the vehicle kilometrage on a national level for different road groups. Some countries have also introduced travel surveys in order to estimate the person kilometrage for different road groups on a national level. In the first case, IRTAD makes it possible to compare different countries, or road groups in different countries, concerning the number of accidents or number of injured in relation to the vehicle kilometrage. The same applies to killed and injured among different road user groups using estimates of person kilometrage. One limitation of IRTAD is that vehicle occupants are not divided into drivers and passengers. This information can be obtained from national accident statistics. In the report, master samples are presented as one possibility for expanding the collection of information on accident factors or the use of different traffic safety measures among road users or vehicles in traffic. The increased use of travel surveys on national levels lends a new dimension to the use of accident statistics, which is presented in the report. Fatality rates and injury rates (killed or injured in relation to person kilometrage) are presented for various countries. The effect of different levels of underreporting of accidents is also treated in comparisons of the safety situation in a number of countries. (Author/publisher)
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