JACKSON, Wyo. — The WY22 bridge expansion, and the potential road expansion anticipated to follow in the future between Jackson and Wilson, includes four new wildlife crossings. But research suggests those crossings might not be enough to offset the impact on local species of construction for a high-capacity road.
Last month, conservation author Ben Goldfarb came to Jackson Hole to discuss his research on road ecology in light of WY22’s road work. His research identifies a collection of problems that Goldfarb says compromises the ability for wildlife crossings to alleviate the pressures of roads on the local ecology. He notes that roads can be sources of pollution, vectors for non-native plant invasion and zones of erosion that can smother streams.
But according to Goldfarb, the primary concern for wildlife is noise pollution from construction and increased traffic that can mask songbird mating calls and create an acoustic envelope that impedes the abilities of all species. Since most road noise above 30mph is tire noise, not engine noise, electric vehicles contribute to that noise pollution just as much as other cars on WY22, where the speed limit reaches 50mph in some sections.
Goldfarb says every three decibel increase in noise can reduce an animal’s listening area, or the area in which an animal can pick up a signal like an alarm call or indication of prey, by 50 percent. According to the National Processing Center, an individual car traveling at 50mph produces an average of 70 decibels of sound in a 50-foot radius. An individual truck at the same speed averages 81 to 85 decibels of sound at 50 feet.
“The idea of using wildlife crossings to justify large road construction and expansion projects is dubious at best.”
Ben Goldfarb
“We know that wildlife crossings are good, but we also know they don’t make roads ecologically benign,” Goldfarb said in his author talk. “There are all of these problems…that wildlife crossings really don’t address. The idea of using wildlife crossings to justify large road construction and expansion projects is dubious at best.”
But Environmental Services Manager for the Wyoming Department of Transportation (WYDOT) Scott Gamo says installation of wildlife crossings has been proven to effectively reduce wildlife-vehicle collisions, which remain a critical part of both human and wildlife safety. He tells Buckrail that reductions in collisions have been seen at several project areas in the state where installed underpasses and overpasses exist, most recently at the newly constructed underpasses at Dry Piney.
“WYDOT routinely monitors wildlife use of crossing structures for multiple years post-construction to evaluate their effectiveness,” Gamo says. “We also continue to sponsor wildlife research projects through our research program.”
Gamo says WYDOT has begun an environmental study process on addressing WY22, which WYDOT Public Relations Specialist Stephanie Harsha tells Buckrail will be used in conjunction with the 2014 Planning and Environmental Linkages (PEL) study. The new corridor study aims to help identify what improvements on WY22 will look like based on the needs assessed in the PEL.
The PEL does contain potential plans for expanding certain segments of WY22 into four-lane highways. According to Goldfarb, highway expansion increases habitat fragmentation and risks to wildlife safety. But the PEL suggests that “because wildlife has likely already habituated to traffic disturbance on WY22, they may also habituate to disturbance from increased traffic levels resulting from widening the highway.”
To Goldfarb, though, that doesn’t ring true. Goldfarb explains to Buckrail that as larger highways carry more traffic, more traffic then carries more noise and light pollution. With this in mind, Goldfarb suggests any expansion of WY22 supporting heavier traffic flow will render the wildlife crossings less effective as wildlife is deterred from the area. He goes so far to say the extent of noise, light and environmental pollution disproves wildlife crossings as mitigation for the road’s impact as a whole.
