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. As part of this rationalisation, many speed zoning changes occurred across Victoria, with some of the most notable being the phasing out of 75 km/h speed zones and the introduction of 50, 70 and 80 km/h zones. Under the rationalisation, posted speed limits on some road sections were increased while on other road sections the posted speed limits were decreased. This study updates an earlier one which evaluated the casualty crash effects of the speed zone changes implemented in Victoria for speed zone changes other than 100km/h to 110km/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. Results are presented for the whole of Victoria as well as for metropolitan Melbourne and the rest of Victoria separately. 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. Results of analysis in metropolitan Melbourne showed an overall increase in casualty crash frequency of 4.7 percent with marginal statistical significance whilst no statistically significant change in casualty crash frequency was found in the rest of Victoria. The net effect of the speed zone changes over Victoria as a whole was a statistically significant increase in overall casualty crash frequency of 5.4 percent. (A)
Samenvatting