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Road Management & Management 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?

Roadside Wildlife Reflectors--Do They Work?

Collisions between wildlife and vehicles cause many deaths and injuries each year, and the economic cost of these collisions is high. Recognizing this growing problem, highway maintenance departments have good reason to investigate the effectiveness of preventive measures.

The Insurance Institute for Highway Safety called roadside wildlife reflectors "the most promising system for preventing deer crashes." However, researchers who have studied the effectiveness of roadside reflectors report conflicting findings.



A 1993 Federal Highway Administration report by S.G. Ford and S.L. Villa indicated that California tested Swareflex Wildlife Reflectors on a four-mile section of State Route 36 in Plumas County. This section of highway was chosen for the experiment because of its exceptionally high mule deer kill rate. After three seasons of intermittent operation, deerkill statistics showed no significant difference between times when reflectors were in operation and times when they were not.


In a 1991 Colorado Department of Transportation report, D. Woodham wrote about the installation of Swareflex Reflectors near Denver. For three months, two half-mile sections of reflectors were alternately uncovered and covered. While no deer-vehicle collisions happened in the test sections during the three months, the experiment proved too expensive to continue. Researchers mentioned the need for more investigation to find out how effective reflectors are for mule deer and suggested a large- scale, regional study using pooled funds and emphasizing valid results.


James R. Gilbert described a Maine research project in a May 1982 report called "Evaluation of Deer Mirrors for Reducing Deer- Vehicle Collisions." Between Topsham and Gardiner on newly opened I-95, twelve random half-mile test sections were established along almost fifteen miles of roadway. The research took place from October 1977 through July 1981 and used Van de Ree Mirrors (polished stainless steel squares with indentations at each corner and one in the middle) in each test section, leaving non-mirrored areas of at least a half-mile between test sections. The number of deer killed was smaller than expected and decreased markedly after the initial opening of the freeway. Researchers conjectured deer became acclimatized to the new road and remained on the highway for shorter periods, resulting in fewer deerkills. Given the small sample and "the fact that more deer were killed in the mirrored areas than the non-mirrored areas," the researchers concluded "that the mirrors were probably ineffective and anyway not justified in areas with so few deer- vehicle accidents."

Gilbert offered a chronology of experiments conducted before his 1982 report. He described the original test with Van de Ree Reflectors. That test was in the Netherlands and compared deerkill figures between 1958 and 1960, before reflectors were installed, with figures between 1960 and 1962, after reflectors were installed. Twenty deer were killed on the roadway when there were no reflectors, and none were killed during the two years after installation. Attempting to duplicate this apparent success, subsequent studies using Van de Ree Reflectors took place in Indiana, Colorado, and Michigan. All led to the conclusion that the mirrors were not effective.

The original research on Swareflex Reflectors, according to Gilbert, was conducted in Austria during the early 1970s. Before-and-after figures for forty-two segments totaling 58 miles of roadway and spanning from three to twenty-four months "indicated a reduced kill." A subsequent test in Colorado failed to find Swareflex Reflectors effective.

Gilbert criticized the design of many of the studies cited above. He contended the size of the sample used in some experiments was not large enough to represent statistically valid evidence. Moreover, he pointed out:

Very few of the studies have incorporated any statistical design into their planning. Especially critical in developing a project is to eliminate the effect of year to year fluctuation in the number of deer crossing the right- of-way. . . . Another problem which could arise is comparing the numbers of deer killed at one time of year (with no treatment) to those killed at another time of year (with treatment). That deer activity and susceptibility to vehicles varies with the time of year is well known.
Comparing Van de Ree mirrored reflectors with Swareflex's prismatic system, John Strieter of Strieter Corporation (exclusive U.S./Canadian importer and distributor of Swareflex Reflectors) observed that the single flash of the mirrors presents a different visual obstacle to deer than the traveling, red beams of light reflected by the Swareflex devices. The latter, according to Strieter, has proven more effective.

However, given the information from the Maine experiment described above and from other studies of deer reflectors, Gilbert finally concluded, "There is no statistically valid evidence that either the Van de Ree stainless steel mirrors or the red Swareflex Reflectors reduce vehicle-deer collisions."

Ontario, Canada

In a report for the Ontario Ministry of Transportation, J.J. Armstrong described an installation of Swareflex Wildlife Reflectors during the summer of 1990 on a two-lane section of a highway in southern Ontario. For a year, crews covered and uncovered the reflectors during alternate weeks and counted the number of deer killed. Results showed the mirrors made no significant difference. Individuals who observed deer behavior when a vehicle passed claimed the animals seemed to react more to the passing vehicle than to light patterns created by headlights bouncing off the reflectors. Researchers concluded it would not be cost-effective to use reflectors to reduce deer-vehicle collisions on this section of Ontario roadway.

Washington State

In May 1992, Mary Ossinger wrote a report on a Washington State deer-reflector study then in progress on Highway 101 near Discovery Bay (northwestern Washington on the Olympic Peninsula). Hoping to duplicate a successful test in Eastern Washington, for three years the Washington Department of Transportation alternately covered and uncovered reflectors installed in six test sections. The test sections were in densely forested areas inhabited by blacktail deer. Of nighttime deerkills, twenty happened when the reflectors were active and twenty-one when they were covered. Ossinger concluded, "Analysis of the test data shows that the Swareflex Reflectors do not significantly reduce deerkill in the Discovery Bay area."


Archie F. Reeve and Stanley H. Anderson called their report on a Wyoming test of wildlife reflectors "Ineffectiveness of Swareflex Reflectors at Reducing Deer-Vehicle Collisions." The report appeared in a 1993 Wildlife Society Bulletin. Crews installed reflectors on U.S. Highway 30 and alternately uncovered and covered them for one-week and two-week periods for three years (October 1986 through the summer of 1989). During the test period "the observed number of deer killed when Swareflex Reflectors were uncovered was greater than expected," leading Reeve and Anderson to conclude, "Without asserting that Swareflex Reflectors actually increased deer-vehicle collisions, they did not diminish the problem on our study area." The authors cited numerous inconclusive studies as further evidence that Swareflex deer reflectors are ineffective. It is interesting to note the report's assertion that "[t]he reflectors deteriorated during the 3-year study." The authors went on to explain that only 61 percent of the reflectors were functioning properly by the end of the study. Apparently crews did not maintain the devices.


British Columbia, Canada

In the Smithers area of British Columbia, Canadian highway officials and the Canadian automobile insurance company shared the cost of installing Swareflex Reflectors on highways and railroad lines. John Young wrote about the project in The Interior News, calling his article "Moose Reflectors Target Hot Spots." In British Columbia, where moose-vehicle collisions are a major problem, 6,411 wildlife-vehicle collisions in 1994 cost the insurance company $11.3 million. According to Eric Becker, area highway manager for Smithers, "Animal collisions dropped dramatically in other areas of B.C. when reflectors were set up. In all cases there's been a reduction."


Reflectors were installed along a quarter-mile section of Dubuque Street in Iowa City at a cost of $4,406 for reflectors (including extras for replacement needs), materials, installation labor, pruning labor, and equipment rental. In an area with a high deerkill rate, the reflectors completely eliminated deer- vehicle collisions during the first two months after installation. According to her December 5, 1994 memo, Lisa C. Goodman, Director of Animal Control for the Iowa City Police Department, found the reflectors are "worth the money, when public safety, public relations, animal safety and the costs incurred by accidents, is taken into consideration."

G. I. Hoilien of Harpers Ferry wrote to Strieter Corporation, distributor of the Swareflex Reflectors called Strieter-Lite, to report, "After thirty years as an Iowa Conservation Officer (Game Warden) in the business of protecting wildlife, I've seen something 'Really Work'!" He explained that he had documented about fifty deerkills, mostly at night, each year on Highway 76 in the three years before the installation of Swareflex Reflectors. Hoilien wrote, "After 7 years only 7 deer have been reportedly killed in this area at night, which makes a saving of 350-400 deer car accidents."

The conservation officer added personal testimony on the effect reflectors have on deer and other wildlife. He explained:

On patrol one night, I just entered the reflected area and in my lights observed several deer running hard towards the highway. When they neared the reflectors, it was as if they had hit a fence. They skidded to a stop, turned and ran back the way they had come. On other occasions, I've observed fox and coyote with the same reaction.


Susan Mulvihill, Accident Surveillance/Safety Engineer for the Minnesota Department of Transportation, reported on the effectiveness of Swareflex Reflectors in a May 1990 letter to John Strieter. For several sites where reflectors had been installed, she estimated an overall deerkill rate reduction of 60 percent. While the reflectors reduced deer-vehicle collisions wherever they were installed, the rate of reduction varied with deer population, roadway traffic volumes, and number of roadway miles in areas densely populated with deer.

The Tri-County River Bottom Bucks Chapter in Paynesville, Minnesota purchased reflectors for use in that area. In a letter from their secretary/treasurer, they reported a drop from 30 deer killed per year to three and added:

These Reflectors have been working better than expected. We like to keep them replaced because we have learned that if one is missing, it's like opening up a gate, and roadkills occur there.


From Rhododendron, Oregon, Michael P. Jones of The Wildlife Fund wrote to Strieter Corporation in September of 1989. He reported that installing Swareflex Reflectors on Highway 26 in the Mount Hood corridor had resulted in a decrease in the number of deer and other wildlife killed on the highway. Writing about the effect of installing reflectors, Jones shared:

No longer are we observing dead skunks, raccoons, jackrabbits, porcupines, or opossums in or alongside the highway. Swareflex is a "godsend" for wildlife. This reflector system is one of the most important devices ever designed to benefit our wildlife.

Washington State

A test of Swareflex Wildlife Reflectors on Highway 395 in Eastern Washington near Spokane was the source of information in a Washington Department of Transportation report dated August 1984. James A. Schafer, Stephen Penland, and William P. Carr wrote the report entitled "Effectiveness of Wildlife Warning Reflectors in Reducing Deer-Vehicle Accidents in Washington State." They described an experiment from 1981 to 1984 in which reflectors in four test sections were alternately covered and uncovered. Resulting figures showed fifty-two deer killed in the test sections at night while reflectors were covered and six while they were uncovered. This significant difference suggested "the reflectors were effective on this highway during this time period."

Mary Ossinger's 1992 report on the ineffectiveness of reflectors in Western Washington mentioned these Eastern Washington tests and the conflicting results. She suggested the difference might be due to the terrain and the species of deer involved. The Eastern Washington test was in an area of open ponderosa pine inhabited by whitetail deer, while the Western Washington experiment took place in a densely forested area populated by blacktail deer.

Click Here to see Graph


According to an article in the July/September 1995 issue of the Michigan Transportation Technology Transfer Center newsletter, Wisconsin's Fond du Lac County Highway Department collaborated with Whitetails Unlimited to install Swareflex Reflectors along a one-mile section of Highway 26. Whitetails Unlimited purchased the system--at a cost of $7,000 to $9,000 per mile for a two-way, two-lane roadway--and county workers installed and maintained it. On this stretch of highway, which is wooded on one side and has a cornfield on the other, vehicles had been killing one or two deer each week. Steve Chicka, county engineer, reported that the figure had dropped to only five or six deerkills for the entire year. Moreover, in a letter to Strieter Corporation in 1990, Chicka commented on three deerkills that happened in the reflector area during the winter of 1989- 1990. He explained:

All 3 of the "kills" occurred right in the area where the reflectors had been missing or knocked down. The effectiveness of the reflectors became quite obvious when we discovered that all of the kills had occurred in places where we had "gaps" or "holes" in our reflector coverage. Since replacing the missing/broken reflectors, we have recorded no new "kills" in this area as of this time.

Within the city limits of the city of Menomonie, the deerkill rate was at nine to twelve per month, and a local woman died in November of 1986 when her vehicle struck a deer. After a joint effort of federal and state highway departments and private agencies funded installation of Swareflex Reflectors on two sections of the freeway in 1993 and 1994, the nighttime deerkill rate dropped by as much as 67 percent at one milepost where deer crossed frequently. Authorities believed the rate would have dropped more if snow did not occasionally cover the reflectors and render them ineffective.

In Kewaunee County, where 40 percent of reported accidents involved deer, Swareflex Reflectors reduced that accident rate from 50 to 100 percent. These figures came from Michael A. Hessel of the Kewaunee County Sheriff's Department. The November 20, 1991 issue of the Wisconsin State Journal shared a comment from Kirk Konkel, a state area maintenance supervisor responsible for Kewaunee County. Konkel had seen deer react to the reflectors along Highway 33, and he claimed, "I've seen them line up like cattle line up at a fence."

Copyright © 1997 by TranSafety, Inc.

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