PROBLEMATIK PRAVENTIVER SCHALTUNGEN VON STRECKENBEEINFLUSSUNGSANLAGEN [PROBLEMS CONCERNING PREVENTIVE VARIABLE SPEED LIMITS IN DYNAMIC SPEED MANAGEMENT SYSTEMS]

This study focused on gathering empirical data on the effectiveness of preventive strategies involving dynamic speed management systems and identifying possible influential factors. The effectiveness of preventive variable speed limits was examined using several new methodical approaches based on traffic flow measurements from three German autobahns. The response in the average speed level of passenger cars attributable to variable speed displays was found to be favorable yet small. However, it was clearly demonstrated that traffic characteristics indicated improved traffic safety for all the preventive variable speed limits investigated. Surveys and laboratory investigations revealed that al safety related signs are interpreted quickly and for the most part,correctly. It was found that compliance was hampered by major discrepancies between posted speed limits and actual traffic situations. It was concluded that the greatest potential for improvement can be found in optimizing the performance of incident detection algorithms along with a clearer differentiation between warning and preventive strategies.