EVALUATION OF THE CRASH EFFECTS OF THE CHANGES IN SPEED ZONES IN VICTORIA DURING 1993-1994 (EXCLUDING 100 to 110km/h)
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 either increased or decreased on many roads. This study estimated the casualty crash effects of the speed zone changes implemented in Victoria for speed zone changes other than the 100km/h to 110km/h changes. Effects have been estimated for the program of speed zone changes as a whole, for Melbourne and the rest of Victoria, general increase and decrease of zoned speed and for each particular type of speed zone change. Results are further related to results of speed monitoring.
In Metropolitan Melbourne, assessment of the general effects on casualty crash frequency of increasing zoned speed showed a statistically significant 9.3% increase. In contrast decreasing zoned speed resulted in no statistically significant change in casualty crash frequency. Results for particular speed zone changes were also obtained. These were generally consistent with the results of speed monitoring. Analysis of the casualty crash frequency change for all speed zone changes combined in the rest of Victoria as well as analysis by specific speed zone changes showed no statistically significant changes in crash frequency. The net effect of the speed zone rationalisation over Victoria as a whole was a statistically significant increase in overall crash frequency of 5.4%.