The impact of replacing heavy passenger vehicles (LTVs and SUVs) in the British Columbia fleet with lighter versions.

Objective: The study reported in this article addressed the potential safety impact of consumer movement toward smaller vehicle choices by examining the makeup of the full British Columbia (BC) vehicle fleetfrom smaller cars to heavy commercial vehicles. The basic assumption made was that some operators of heavy light trucks/vans (LTVs) or sport utility vehicles (SUVs) would, in the short term, be induced to downsize to lighter vehicles of the same type. Method: The 2000-2007 BC crash-claim data at the Insurance Corporation of British Columbia (ICBC) was used to create matrices of average information by culpable and nonculpable entities in two-vehicle collisions in 15 weight categories. Models for the effects of various driver/crash characteristics on injury potential were created and used to adjust the effect calculated solely on the basis of weight change. Levels of heavy LTV/SUV replacement from 0.05 to 0.95 of the current population were tested and the redistribution of vehicles was done in such a way that the relationship between small-large vehicle injury ratio and large-small vehicle mass ratio over the whole fleet remained constant as did the relative proportions of culpable and nonculpable involvements. Results: The net effect of downsizing in the manner assumed for this study was mildly positive in terms of overall injury riskthat is, downsizing resulted in slightly fewer total injuriesbut not in the case of fatalities, which tended to be increased by a more substantial margin. However, the results showed that even replacing substantial proportions of the heavy LTV/SUV population would not result in a large impact on safety. Conclusions: Replacing almost all the heavy LTV/SUVs with lighter versions should reduce injuries by less than 1 percent and increase fatalities by 3.5 percent percent. Nevertheless, in terms of persons impacted and the associated costs, the effects would be noticeable. The issue for policy-makers is to judge how the environmental benefits associated with encouraging such change compare with the net costs in terms of safety outcomes.