Wildlife-vehicle collisions along busy state Highway 75 through the Wood River Valley, which kill over 100 deer and elk annually, could be reduced by installing high-tech animal-detection systems or far more costly wildlife passage structures, a researcher told local officials Thursday.
Along the scenic 26-mile stretch of highway between Timmerman Junction and Ketchum, thousands of weekday commuters make daily pilgrimages. Invisible to many of them is a daily pilgrimage of an entirely different sort that sends critters large and small across the busy highway. Many of the attempted crossings result in the sudden collision of moving automobile and wildlife.
Blaine County officials would like to reduce those collisions as much as possible. They and the Idaho Transportation Department contracted with the Western Transportation Institute at Montana State University in Bozeman to conduct a study on wildlife collisions and provide recommendations for reducing them.
Early last year, researchers began to track the numbers and locations of roadkills, focusing on mule deer and elk. In March, they wrapped up the one-year study and compiled the results into a lengthy draft report.
On Thursday, one of the transportation institute's lead researchers, Dr. Marcel Huijser, presented the results of the survey to the county commissioners and the Wood River Regional Transportation Committee.
The results include roadkill survey data collected by Angela Kociolek, a field biologist working for the transportation institute, as well as carcass removal data from the Idaho Transportation Department, Idaho State Police accident reports and reports made by the public on the "Ketchum on the Road" wildlife reporting Web site.
Based on the four sources of information, a minimum of 134 collisions with deer and elk were found to have occurred in the 26-mile study area in 2007. Estimates from the years 2004 to 2006 ranged from 25 to 40 road-killed deer and elk, but those were based on ITD and Idaho State Police information only.
The study found that most collisions occur during early morning and evening, the busiest traffic hours. It also found that most live and dead deer and elk were seen along the stretch of road from the north end of Hailey to just north of Elkhorn Road. The highest concentration of wildlife-vehicle collisions was in an approximately one-mile stretch just south of Deer Creek Road. Elk are commonly viewed by passing motorists in this area during the winter as they cross the highway from west to east to access open grazing in the Peregrine Ranch area.
According to Huijser, an estimated 1 million to 2 million collisions between deer and vehicles occur in the United States anually. He said these numbers have continued to climb in the past decade. He said that each year, the collisions cause an estimated 29,000 human injuries, 211 human fatalities and $1 billion in damages.
"Animal-vehicle collisions are actually quite expensive," he said.
An issue that motivated the survey is the potential for increased wildlife collisions that could result from a proposed Highway 75 widening project.
Huijser and several colleagues at the institute considered six options for reducing wildlife-vehicle collisions. They include installation of a remote sensor animal detection system that would alert motorists to crossing wildlife. The systems use a combination of an energy beam—either microwave or infrared—that when interrupted by an approaching animal sends a signal that activates a blinking light to warn motorists. These systems could be combined with animal fencing to guide wildlife to selected crossing points, Huijser said.
On the more expensive end, officials could also consider adding wildlife overpasses or underpasses at key locations along the highway. Combined with animal control fencing, this would allow critters to cross over or under the busy highway without difficulty.
Huijser pointed to an ongoing project along U.S, Highway 93 in Montana that is using a system of similar overpasses and underpasses to allow wildlife to move more freely. Highway work being completed as part of that project will include construction of a large wildlife overpass near a place northwest of Missoula called Evaro Hill, Huijser said. The pass is a known crossing point for sensitive Rocky Mountain species like grizzly bear.
Similar structures have been successfully installed in Banff National Park in Alberta, Canada.
Remote cameras placed under the two Highway 75 bridges between Hailey and Ketchum did prove that some species of wildlife use them as a sort of critter underpass, he noted. However, no elk used the underpasses during the entire study period, likely because of the low height of these passageways, he said.
Huijser said the high number of elk that cross along the under-one-mile section near Peregrine Ranch make that portion of highway a perfect "first candidate" for some sort of mitigation project.
"That is where you would likely focus," he said.
Because of the expense of installing wildlife crossing structures, Huijser seemed more inclined to recommend the use of animal detection systems, though he admitted the effectiveness of these are not entirely known.
The seriousness of the problem, especially for elk crossing near Peregrine Ranch, was not lost on anyone, including retired Idaho Department of Fish and Game Conservation Officer Roger Olson of Hailey.
"I'm wondering why we have any elk left there," he said.
Simply lowering speed limits on key stretches of highway won't solve the problem because commuters are already driving slowly due to bumper-to-bumper conditions during the worst hours, said Blaine County Sheriff Walt Femling.
"There's just a lot of cars out there," he said.
The County Commission and Wood River Regional Transportation Committee indicated they will consider the new information and come up with recommended actions that Huijser will incorporate in a final report.