Factors influencing the location of deer-vehicle accidents in Iowa.

Half a million deer-vehicle accidents (DVAs) occur annually on North American roads, yet the possible factors associated with these accidents are not well understood. We examined the influence of landuse patterns and highway characteristics on Iowa DVAs from 1990-97. Over 25% of DVAs occurred at 3.4% of all mileposts in Iowa. Annually, the greatest numbers of DVAs occurred in May and November. We examined 2.59-km2 areas around a set of randomly selected milepost locations (n = 1,284) to identify factors that may have influenced DVAs. Stepwise logistic regression produced a 6-variable model ($chi ^{2}{}_{6}$ = 331.543, P = 0.001) that included 4 landscape variables, the number of bridges, and the number of lanes of traffic. A factor classification tree constructed from these variables revealed that 97% of mileposts associated with ≥4 bridges were "high" DVA sites (≥14 DVAs). The logistic model correctly classified 63.3% of 245 sites in a validation data set. Our results suggest that mitigation of DVAs should be focused on areas with a high number of bridges.