During late 1992 and early 1993, 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 whilst on other road sections the posted speed limits were decreased. This study evaluates the casualty crash effects of the speed zone changes. Analysis of the effects of speed zone changes on casualty crash frequency showed an overall increase in casualty crash frequency of 6.9 percent, although this result was of marginal statistical significance. Assessment of the general effects on casualty crash frequency of increasing zoned speed or decreasing zoned speed showed no statistically significant change in casualty crash frequency when the zone speed was decreased, and an 8.7 percent casualty crash increase (with marginal statistical significance) when zone speed was increased. Most of the speed zone changes which occurred in the rest of Victoria took place on the fringes of country towns in the speed transition zones between 100 km/h zones of the open highway and 60 km/h zones of the built up town area. The overall casualty crash frequency change for all speed zone changes combined in the rest of Victoria was estimated as a 32.9 percent reduction; however, the statistical significance of this result was marginal. (A)
Samenvatting