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Tunnel use by wildlife aids driver safety
20130131-Verulam Farm Underpass
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Tunnel under I-64 at Verulam Farm
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by Tim Shea | Sunday, February 10, 2013 at 12:02 a.m.

Below Interstate 64, wild animals are making use of their own transportation network. By avoiding the roadways here and around the state, they are saving drivers millions of dollars in damage to health and personal property.

I-64 runs through the 1,700-acre Verulam Farm in Albemarle County, which has a 10- by 12- by 189-foot tunnel that goes under the highway. The tunnel was installed during the highway’s construction in 1968 for cattle to access the other side of the road.

“Deer use it all the time,” Verulam owner Melton McGuire said. “And there aren’t collisions here. I see far more [collisions] on Route 250 than I do on 64.”

The financial savings were most recently documented in a 2005 study by the Virginia Center for Transportation Innovation and Research, which estimated that in 2003 Virginia likely saw more than 34,000 deer-vehicle collisions and about $40 million in property damage.

The study, “The Use of Highway Underpasses by Large Mammals in Virginia and Factors Influencing their Effectiveness,” recommended that the Virginia Department of Transportation consider constructing wildlife crossings when building roads.

Bridget Donaldson, a senior research scientist at the innovation center and study author, said that no wildlife crossings have been built in Albemarle since the article’s publication.

“One reason we’re not doing anything here is that we don’t have a lot of new road construction,” Donaldson said, “but, hopefully, we’ll start to do more, or do more with [the roads] we’ve already got.”

From June 2004 to May 2005, Donaldson monitored seven existing box culverts and underpasses throughout the state — all constructed for purposes other than wildlife — to determine the structural and geographical attributes of successful crossings. The tunnel at Verulam was one of the sites.

The researchers affixed remote cameras near them to monitor wildlife usage.

The cameras captured 2,702 wildlife pictures and confirmed that 1,040 white-tailed deer crossings occurred in the most popular structures. Six of the images were of black bears, but no bears entered any of the monitored underpasses. Deer were the heaviest users.

Due to small sample sizes, and to determine how effective the underpasses were at preventing deer-vehicle collisions in the years prior to the study, Donaldson consulted data collected by Virginia’s Highway Traffic Records Information System from 1997 to 2001.

That data shows that as far as 1.25 miles east and three-quarters of a mile west of the underpass at Verulam Farm, there were no deer-vehicle collisions in that five-year period.

Donaldson recorded 319 deer crossings at Verulam Farm during the study.

The structures that are attractive to deer had heights of 12 feet or more and natural features such as dirt floors, nearby forest cover and clear visibility to the other side of the underpass.

However, while the study’s focus was wildlife, its purpose was finding ways to protect humans by preventing deer-vehicle collisions.

“When it comes to [deer-vehicle collisions]," Donaldson said, “deer aren’t an endangered species here, so [preventing such wrecks is] about the human safety factor.”

Albemarle police spokeswoman Carter Johnson confirmed that in 2012, there were 115 wildlife collisions, 109 of which involved deer, and that there are significantly more deer-vehicle collisions that go unreported. (According to Donaldson’s study, only one in six deer-vehicle collisions are reported in Fairfax County.)

In a 2009 animal-vehicle collision cost-benefit analysis, research ecologist Marcel P. Huijser found that the average total cost per deer-vehicle collision in the United States was $6,617.

This average number includes, among other expenses, $2,622 for vehicle repairs; $2,702 for human injury; $125 for towing, accident attendance and investigation; and $50 for carcass removal and disposal.

Using that data, Albemarle drivers spent at least $721,253 on deer-vehicle collisions in 2012.

Donaldson noted that constructing underpasses after a highway is already built is very expensive, but that there are ways to guide wildlife to the existing crossings.

“It may be that the most effective thing to do for existing structures is to add fencing,” she said.

Often, fencing will be added along the highway’s shoulder near an underpass to keep animals from approaching the road. The fences run parallel to the road and then angle into the woods. When approached from the forest, the fencing guides the animal toward the underpass.

“Once the animal knows it’s there, they will continue using it,” Donaldson said. “In large, every study that has looked at wildlife crossings with fencing finds them to have an 87 percent effective rate.”

Could more wildlife tunnels be built as new roads are constructed in parts of rural Albemarle? A leading contender might be the planned U.S. 29 Western Bypass as it bisects farms between Barracks Road and the South Fork Rivanna Reservoir.

McGuire said that if the Western Bypass bisected land he owned, he would prefer to have a wildlife crossing.

“Yes, I’d like to have one,” McGuire said, “though I’m not sure that you have any legal right to require VDOT to build one.”

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