by Matt Rosenberg August 31st, 2011
SUMMARY: Collisions between vehicles and animals exact a large toll in injury and property damage every year in the U.S. and also have a significant impact in Washington state. A new study led by the director of a transportation research laboratory at the University of Washington in Seattle shows the probability of animal-vehicle collisions is increased on rural two-lane roads near white-tailed deer habitats, while the likelihood of such accidents is lowered if the road is wider, the animal is male rather than female, and the vehicle is a truck, not a car.
BACKGROUND: There are an estimated 1.5 million annual deer-vehicle collisions in the U.S. and in Washington State, about 3,000 a year between vehicles and deer or elk on Washington state highways alone. Animal-vehicle collisions cause about 200 human fatalities and 20,000 human injuries per year in the U.S. and result in annual property damage exceeding $1 billion. A new statistical model was devised by a University of Washington research team to improve understanding of the human, animal and interactive factors contributing most greatly to such mishaps. In their study researchers used animal carcass removal data from the Washington State Department of Transportation including location, date, weather, animal type, sex and age; GIS-based maps showing population distribution in the state for mule-deer, white-tailed deer and elks; and official data on road and shoulder width, and speed limits.
KEY LINK: “Modeling Animal Vehicle Collisions Considering Animal-Vehicle Interactions,” draft of paper to be published in November, 2011 edition of Accident Analysis and Prevention. Lead author: Yinhai Wang, Department of Civil and Environmental Engineering; Director, Smart Transportation Applications and Research Laboratory; University of Washington.
- Higher speed limits and higher driving speeds increase the probability of an animal vehicle collision. Vehicles traveling at higher speeds need a longer stopping distance if an animal is spotted in the road, and the reaction time is less. The driver’s probability of an ineffective response “goes up significantly” when the speed limit on the road is greater than 50 mph.
- Rural, two-lane roads and the presence of a white-tailed deer habitat also increase the likelihood of collisions between vehicles and animals. There are more animals in rural areas, and data show that driving through white-tailed deer habitat makes the probability of a collision “much higher.” Transportation agencies should consider lowering speed limits on roads which go through or adjacent to white-tailed deer habitats.
- Animal-vehicle collisions are less likely to occur if the animal is male, the vehicle is a truck, and the road has a relatively large number of lanes. Male animals have a lower risk of collision because they’re more alert; they respond to collision threat and run away faster than females. Trucks typically go slower than passenger vehicles and the driver’s seating is elevated, improving sight lines. In addition, trucks are noisier, improving warning signs to animals in or near the road.
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