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Road Management & Engineering Journal
Copyright © 1997 by TranSafety, Inc.
May 12, 1997
TranSafety, Inc.
(360) 683-6276
Fax: (360) 335-6402

Ohio City May Be Liable When Motorcyclist Not Warned of Stalled Front-End Loader on Roadway
Public Agencies Found Liable for Trap-Like Hazard at End of Dead-End Road and Misleading Route Sign on Highway
Deer-Vehicle Collisions are Numerous and Costly. Do Countermeasures Work?
Roadside Wildlife Reflectors--Do They Work?

Deer-Vehicle Collisions are Numerous and Costly. Do Countermeasures Work?

Deaths and Injuries

"Good national statistics don't exist on how many collisions occur between deer and motor vehicles each year," reported the Insurance Institute for Highway Safety in its April 3, 1993 (Vol. 28, No. 4) Status Report article called "Deer, Moose Collisions with Motor Vehicles Peak in Spring and Fall." The article added, "The estimate is hundreds of thousands." Michigan keeps statistics on deer-vehicle collisions. According to the Michigan Department of Natural Resources, there were 56,666 deer-vehicle collisions in that state in 1994, and each year deer-vehicle collisions in Michigan kill an average of five people and injure 1,500. The National Highway Traffic Safety Administration estimated that animal-vehicle collisions in the United States caused 120 vehicle-occupant deaths in 1991. According to the National Safety Council in Chicago, deer-vehicle collisions annually account for more than 100 motorist deaths and about 7,000 injuries. These collisions kill as many as 350,000 deer each year.

Economic Costs

Death and injury costs of deer-vehicle collisions are high; so are the economic costs. The National Highway Traffic Administration's 1990 figures set the lifetime economic costs to society of each traffic fatality at $702,000 and the average cost for each critically injured person at $589,000. Conservatively figured, the annual national cost in motorist loss of life and injury from deer-vehicle collisions is almost $200 million. In addition, the average cost of vehicle damage from hitting a deer is $2,000. Estimating 350,000 such collisions a year (based on only those deer kills reported), the total annual cost of vehicle repair is $700 million.

Moreover, deer and other game animals are a natural resource with economic value derived from hunting expenditures. The Michigan Technology Transfer Center placed the economic cost of a lost deer at between $700 and $1,000. Additional expenses resulting from deer-vehicle collisions include accident investigation and removal of dead animals from the highway.

Deer-vehicle collisions are becoming more frequent as deer populations thrive, vehicle miles traveled increase, and people continue moving to rural areas heavily populated by deer. The growing number of insurance claims that are resulting from animal-vehicle collisions contributes to escalating premiums.

Preventive Measures

Highway safety advocates emphasize that the best way to prevent deer-vehicle collisions is vigilance. In daylight hours, the watchful motorist can often see an animal at the side of the road, or on the road, soon enough to avoid a collision. In darkness, however, motorists frequently do not see an animal until it is too close to avoid. For this reason, and because many animals are most active during the evening and early morning hours, 90 percent of deer-vehicle collisions happen between dusk and dawn.

To reduce collisions between vehicles and animals, agencies responsible for highways are using several preventive measures-- including signs, fences, underpasses, diversionary feeding areas, expanded hunting seasons, and roadside reflectors. Motorists themselves are trying whistles and other noises to warn animals of an approaching vehicle.


Deer-crossing, moose-crossing, and even goose-crossing signs are common throughout the United States. Signs let motorists know that they are likely to see a certain kind of animal on the road in this area. While signs may be effective in alerting motorists of a hazard when they are unfamiliar with an area, safety experts feel the warning is largely disregarded, especially by motorists who travel a road frequently.


Highway maintenance crews sometimes install fences along roadways in areas where animals frequently cross. Fences are an expensive preventive measure to install and maintain, and they are not always effective. Deer will jump a fence or dig under it in order to follow their well-established feeding or migration path; once an animal is on a fenced roadway, it may have trouble getting off. In addition, fences are designed to prevent game from crossing the roadway--any time of the day and whether vehicles are present or not. Once animals realize that crossing in one area will always be difficult, they are likely to establish an alternate crossing at one end or the other of the fenced portion of the road.


In an article called, "Clash of Deer and Man Tests Public Ingenuity," the September 10, 1990 edition of The New York Times NATIONAL reported, "In Colorado and some other Western states, officials have even built underpasses to funnel deer beneath busy highways." Alaska has also tried providing tunnels to keep moose off freeways. The cost of building such underpasses is high.

Diversionary Feeding Areas

The number of collisions between deer and vehicles increases in the spring and fall. Deer move more widely throughout their entire feeding range in the spring; therefore, they cross roads more frequently. Also, in late winter and early spring deer in mountainous western states move to lower elevations to feed. The fall mating season contributes to the increased movement of deer and other animals. In some mountainous western states, game officials and biologists have set up diversionary feeding areas away from roadways so that animals coming down from higher elevations in search of food will not cross the road. This practice is labor intensive and expensive, and it is only effective in certain types of terrain.

Expanded Hunting Seasons

In states where deer herds are thriving, officials have lengthened the hunting season and increased the limit on the number of animals hunters can take. Michigan's deer population peaked at 1.7 million in 1989. Since then, longer fall hunting seasons had decreased that number by nearly 10 percent. The goal, according to an official from the Department of Natural Resources, is to cut the herd to 1.3 million by 1992.

Roadside Reflectors

Given the high percentage of deer-vehicle collisions that happen at night, some highway departments are installing reflectors at regular intervals along the side of the roadway in areas where deer and other animals frequently cross. The most commonly used of these devices, the Swareflex Wildlife Reflector, reflects light from an approaching vehicle's headlights to create a low-intensity red beam that bounces across the roadway and into ditches and woods. Drivers will not see the reflected light; however when an animal comes upon the unnatural and apparently moving light patterns, it is stopped from crossing the road. After the vehicle has passed, the lighted "fence" disappears, and the animal may continue safely on its way.

The Insurance Institute for Highway Safety described the reflectors as "the most promising system for preventing deer crashes."

Whistles and Other Noisemakers

Ultrasonic whistles mounted on vehicle bumpers emit a shrill tone when air passes through them as the vehicle travels over thirty miles per hour. Manufacturers claim these whistles are audible to deer (but not to humans) and effective in frightening deer from the roadway. The whistle is about two inches long and bullet shaped. In 1990, according to The New York Times NATIONAL, deer whistles cost about $25, and such groups as the California, Iowa, and Kansas state police were using them on their patrol cars.

While manufacturers contend deer can hear the whistle up to a quarter mile away, no published research verifies the device's effectiveness. The Insurance Institute for Highway Safety presented evidence refuting claims promoting the whistles:

Georgia's Game and Fish Department, for example, found that in hundreds of observations from vehicles equipped with deer whistles, deer didn't respond. Whistles on vehicles going 25-30 mph produced no ultrasonic sound, although some ultrasonic and lower frequencies were produced when the whistles were blown by mouth. According to wildlife biologists at the University of Georgia, neither deer nor humans can hear ultrasonic sound. Whistles blown by mouth near captive deer produce no response.

A University of Wisconsin study found that three types of whistle did produce low-pitched and ultrasonic sounds at speeds of 30 to 70 miles per hour; however, researchers were unable to verify that deer responded to the sounds, even at distances well below the distances from which manufacturers claim the whistles are heard. Moreover, deer would only be able to hear the whistles if there were a straight shot between the deer and the whistle. If curves, trees, or other obstacles came between the deer and the whistle, the device would be ineffective.

According to an article called "Blowing the Whistle on Deer Scare Devices" in the Mid-February 1993 Farm Journal, the Ohio State Police installed deer whistles on their patrol vehicles; however, they reported finding no significant decrease in collisions between patrol cars and deer. The same article indicated that a panel of the World Society for the Protection of Animals could find no data proving "that such a device can actually stop an animal crossing the road, which is the main purpose of the device." Finally, Washington State University researcher Leonard Askham felt the evidence tended to favor a conclusion that deer whistles do not work. "Even if the devices were effective," Askham warned, "they would soon become clogged with insects and dirt and stop working."

The New York Times NATIONAL described a different, creative way to use sound to frighten deer and other animals off the road and out of the path of oncoming vehicles. The article explained:

Before he discovered deer whistles, a supervisor for an Arkansas utility came up with his own plan to scare deer off dark country roads. He taped the barking of his neighbors' dogs, rigged an amplified speaker to the front of his truck and then broadcast the tape as he cruised down highways.

But he abandoned the scheme, amid concern that the barking was not only scaring deer, but awakening residents of southern Arkansas.

Copyright © 1997 by TranSafety, Inc.

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