Heinz Hoschopf, Ernst Tomasch

• In a first step, we have examined approximately 23 000 single vehicle accidents within the Austrian National Statistics database. In a second step, we considered 15% of all fatal "running off the road" accidents that occurred in Austria in 2003. As a result, two accident categories were specified; "leaving the road without preceding manoeuvre" and "leaving the road with preceding manoeuvre". These two categories can be basically characterised by the vehicle- heading angle and its velocity angle. In this report, we further suggest theoretical approaches for the dimensioning of a safety zone, an area adjacent to the road free of fixed objects or dangerous slopes. We also show the link between the two accident categories mentioned above and the real world accidents analysed in detail. These observations also form the basis for the required length for safety devices. Finally, we summarise accident avoidance strategies.