Two separate and distinct hypotheses or conditions must be valid if a speed limit is to make a contribution to a significant reduction in accidents and casualties: 1) Imposing a speed limit decreases the speeds of faster vehicles; II Decreasing the speed of faster vehicles diminishes the probability of accident occurrence and reduces accident severity. The objective of this study was to test the validity of these hypotheses for the 60 mph general speed limit in Ireland and for the conditions which prevailed during the study period. Conclusions are presented.
Abstract