Reduced roadkill: Fencing cuts collisions; more sections erected
Ever since the Colorado Department of Transportation erected wildlife fencing along Colorado Highway 82 in the Carbondale area in 2009, “it’s made a remarkable difference in roadkill,” said local wildlife advocate and Carbondale town Trustee Frosty Merriott.
Indeed, CDOT’s own numbers bear that out. The agency says animal-vehicle collisions in the Carbondale area of Colorado 82 fell to below 100 in 2010 from the roughly 175 the previous year, and were well under 50 by 2011.
In 2010, CDOT completed a similar project involving fencing and escape ramps for Interstate 70 east of Gypsum in Eagle County. And now, encouraged by the results of fencing work to date, it is undertaking a $4.2 million fencing project in another problem area for wildlife collisions, the I-70 stretch from west Rifle to Canyon Creek, east of New Castle. It’s also doing fencing work as part of a Colorado 82 resurfacing project east of Carbondale this year.
“Wildlife fencing, particularly when installed with other measures like signs and ramps, is typically the most cost-effective way to reduce the incidence of these types of collisions,” CDOT engineer Roland Wagner said in a news release announcing the Rifle project.
From a public safety perspective, such projects make a lot of sense, and Colorado Parks and Wildlife generally supports them, said Dean Riggs, assistant northwest regional manager. But for wildlife, “it’s sort of a good news, bad news thing.”
Although the fencing saves animals’ lives, it also can cut off migration patterns and reduce interaction between herds, and thus genetic variability, Riggs said.
“That somewhat limits or can interfere with our ability to manage those populations in the long run,” he said.
CDOT, which consults with Colorado Parks and Wildlife in considering wildlife measures, also continues to study reduced speed limits and higher fines in wildlife zones as another possible approach but remains unconvinced of their effectiveness. But if the solutions to the problem of animal-vehicle collisions in Colorado aren’t crystal-clear, the problem itself is. Many Colorado roads cross through prime wildlife habitat. I-70 from Vail Pass to the Utah line is largely “right in the middle of winter range,” Riggs said.
That stretch may be bad, but the portion of it from Canyon Creek to west Rifle is even worse, CDOT says. Animal-vehicle collisions from Utah to Vail Pass on I-70 account for 13.6 percent of all reported collisions on that stretch. But they make up 31.6 percent of all collisions from Canyon Creek to west Rifle, and the Rifle area of I-70 ranks in the top 5 percent of roadways statewide in animal-vehicle collisions, CDOT says.
To reduce that problem, CDOT is contracting to have 48 miles of fencing — 24 miles on each side — installed in the project area. Also planned are 54 one-way escape ramps for animals that make it into the highway corridor, and deer guards that act like cattle guards to keep deer from getting into the corridor at highway accesses.
High price tag
Merriott said one concern he had with fencing is that it might result in increased collisions where the fencing stops and animals can cross the roads, but that doesn’t seem to have been a problem where the Carbondale fencing was installed.
“Apparently, no, they don’t just walk down the fence until they can get across like a person might do,” he said.
Riggs said short stretches of fencing might simply cause animals to go around the end of a fence, whereas long stretches may lead them to learn to go someplace else rather than crossing the highway.
Both Riggs and Merriott think wildlife underpasses and overpasses could help retain habitat connectivity even as roadways get fenced off.
“It is certainly a thing that we need to be thinking more about as a state — how do we include these types of structures in highway systems, and fencing opportunities as well,” Riggs said.
But he acknowledged that an overpass is an expensive proposition, and paying for such structures would be a challenge.
Collisions with animals also come with a price tag. CDOT cites Rocky Mountain Insurance Information Association data showing the average property damage costs of collisions involving wildlife during the second half of 2010 and first half of 2011 was $3,171.
A less expensive solution than fencing and overpasses could be reduced speed limits combined with higher fines. CDOT has been experimenting with lower nighttime speeds, partly based on the direction of 2010 legislation sponsored by state Sen. Gail Schwartz, D-Snowmass Village, and former state Rep. Kathleen Curry of Gunnison.
That bill “called for lowered nighttime speeds and doubled fines for speeding at night in designated ‘wildlife crossing zones,’ ” CDOT said in a news release. Based on its direction, CDOT identified 100 miles of such zones where nighttime speed enforcement was feasible.
Where speeds in those zones were posted at 60 to 65 mph, the nighttime speeds were reduced to 55 mph during the migration season, now identified as Oct. 1 through June 1. All 100 miles were posted as wildlife corridors, with doubled fines for nighttime speeding.
Among the corridors that are part of the study are parts of Colorado Highway 13 in the Rifle and Meeker areas, U.S. 50 at Blue Mesa Reservoir, and U.S. 550 between Ridgway and Montrose.
CDOT found an overall 9 percent decrease in animal-vehicle collisions after two years, compared to the prior two years. But it says several variables could be in play, and it is continuing the experiment for two more years, with plans to report back to the Legislature in August 2014.
“We’ve certainly seen (collision) numbers go down in some of these corridors, but not all, and in some corridors it’s gone down day and night,” CDOT spokeswoman Nancy Shanks said.
She said one thing CDOT will do is study speeds in some of the corridors to see if the doubled fines and reduced speed limits actually are resulting in slower driving. If speeds aren’t changing, then the reduced collisions presumably aren’t related to those initiatives.
Statewide, such collisions have generally fallen slightly since 2006, after having exceeded 3,500 per year for several years prior.
CDOT also has found it challenging to set nighttime, lower-speed hours during the migration season. The hours it ultimately designated, 5 p.m. to 7 a.m., are dark in the winter, but some of them are light in the spring, which might confuse motorists.
Riggs said the reduced speed limits should help, but he agreed a lot of variables could be involved and said a lot of collisions will still occur due to issues such as compliance.
To make a significant reduction probably would require speed limits quite a bit lower than even 55 mph, he said.
But he added, “There’s a reality check to that, too. As a society that depends on automobiles for getting from point A to point B, there’s a limit to what we’re going to go down on speed limits.”
“We need to set realistic speed limits, speed limits that are set for specific reasons and are reasonable so they will be followed,” Shanks said.
Ultimately, the best way to reduce the chances of a collision is for drivers to exercise care.
“Keep your eyes open. Expect to see wildlife. Don’t let your guard down,” Parks and Wildlife spokesman Mike Porras said.