During late 1992 and early 1993, a rationalisation of speed limits on Victorian roads was undertaken in order to achieve credible speed limits which were uniform with the rest of Australia. Under the rationalisation, posted speed limits on some road sections were increased whilst on other road sections the posted speed limits were decreased. This study evaluates the casualty crash effects of the speed zone changes implemented in Victoria for all speed zone changes other than 100 km/h to 11O km/h. Effects are estimated for the program of speed zone changes as a whole as well as for each particular type of speed zone change. Estimated effects of speed zone changes on casualty crash frequency are further related to changes in crash type as well as results of speed monitoring. The evaluation found no statistically significant change in overall casualty crash frequency in Victoria due to speed zone rationalisation. Whilst the results of the evaluation presented here are generally based on limited quantities of data after implementation of speed zone changes, this study has established a framework under which the evaluation could be easily repeated at a later date to more precisely estimate the effects of speed zone rationalisation. (A)
Abstract