"Safe Passage: Making state Route 260 safer for motorists and wildlife,"
by Norris Dodd
If you live in or visit Rim Country or the White Mountains of east-central Arizona, you’ve driven picturesque state Route 260 east of Payson up and over the Mogollon Rim. And if you’ve taken this highway at night, especially on Monday or Tuesday, you’ve risked a close encounter of the “cervid” kind. In 2004, vehicle collisions killed at least 81 Rocky Mountain elk and 10 white-tailed and mule deer on a 17-mile section of this highway. One black bear and a mountain lion met a similar fate.
The growing number of collisions between wildlife and vehicles in Arizona is a major safety concern. Collisions with wildlife result in many serious human injuries and one or two human deaths each year in Arizona, along with millions of dollars in property damage. On several rural highways, wildlife-vehicle collisions account for over 60 percent of all single-vehicle accidents.
Since 2000, the Arizona Department of Transportation has been reconstructing state Route 260 from a narrow two-lane to a divided four-lane highway, not only to carry more cars to and from the White Mountains, but also to address safety and wildlife issues. This project is one of the most comprehensive efforts in North America to make a highway friendly to the passage of wildlife. When complete, 11 sets of large, bridged underpasses will facilitate wildlife passage under the highway. Six sets of large bridges over streams will also serve as wildlife passage structures. To date, ADOT has finished seven underpasses and six bridges in the first three of five construction phases.
Electronic Eye on Animals
Are we succeeding at making state Route 260 safer for drivers and more passage-friendly to wildlife? Since 2001, the Arizona Game and Fish Department has worked with ADOT and its other partners in the project, the Tonto National Forest and the Federal Highway Administration, to find out.
We keep an electronic eye on animals, using integrated four-camera video surveillance systems in and around the underpasses. These systems employ banks of infrared lights (whose illumination humans cannot see) to record animals approaching and using the underpasses at night. To date, we’ve captured more than 9,000 animals in 11 species on videotape. Elk account for nearly 80 percent of the animals caught on tape. Half of the critters seen on tape crossed through the underpasses — that’s 4,500 animals that motorists didn’t have to dodge.
We used this system to assess which kind of underpass elk prefer. Two underpasses were built only 750 feet apart at the Little Green Valley meadow complex. One underpass has natural-looking earthen sides and vegetation. The other has 30-foot-high concrete walls that create a tunnel effect. Three times more elk used the more natural-looking underpass compared to the one with walls. Elk appeared to fixate on the tops of the walls, possibly concerned about lurking predators such as mountain lions that often hunt from atop rocky ledges. Based on our Little Green Valley data, ADOT redesigned a planned underpass at Indian Gardens, eliminating concrete walls to enhance wildlife acceptance and use — a prime example of the adaptive management process at work.
Technological Tools of the Trade
In addition to using cameras to watch animals, the Arizona Game and Fish Department uses Global Positioning System technology to track elk movements and highway-crossing patterns. To date, we’ve fitted 110 elk with GPS telemetry collars that receive and store the collar’s location.
- During our first two phases (of three) of elk tracking, we obtained over 230,000 locations from 64 elk. Almost half of these locations were within one-half mile of the highway.
- We counted 6,037 highway crossings, an average of 94 crossings per elk.
- One cow crossed 692 times — and lived. But crossing the highway frequently is risky business: Seven of 14 elk that crossed at least once every other day were killed in vehicle collisions, while only one of the 50 that crossed less often was killed.
Before Fencing:
- 12 percent of elk and deer approaching the highway used the underpasses
- 79 percent of elk crossed the highway “at grade”
After Fencing:
- 56 percent of elk and deer monitored by video systems used the underpasses
- No elk crossed the highway “at grade” near the underpasses
Recorded Traffic Levels
- Average traffic levels on Fridays and Saturdays: more than 9,200 vehicles
- Average traffic level on Mondays: 6,000 vehicles
- Average traffic level on Tuesdays: 5,300 vehicles
Good Fences Make Good Neighbors
From our GPS tracking, we found that elk prefer to cross the highway at specific places. High-crossing areas are close to lush meadows and streams that attract elk for foraging (especially during our prolonged drought). In sections of the highway without such habitats, we recorded few crossings by GPS-collared elk (and few collisions).
The information has proved useful in deciding which sections of the highway should be fenced to reduce crossings over the highway. To construct 8-foot-high elk-proof fencing along the whole highway would be expensive, costly to maintain, visually unattractive, and it would further limit wildlife passage. So we’ve recommended fencing high-crossing zones to intercept elk and funnel them toward underpasses.
For example, we projected that fencing only half of the Christopher Creek section of state Route 260 would intercept 89 percent of elk crossings. Given the high competition for highway construction dollars, this approach gives a good “bang for the buck.” This highway section was rebuilt and re-opened to the public for nearly a year before fencing was installed. During that year we compared the elk-vehicle collision rate, underpass use and passage-friendliness before and after fencing, so we could find out how important fencing is to the overall success of the project.
We discovered that, by funneling elk toward the underpasses where they can cross unimpeded without traffic racing by, fences increase safe passage. And since the fencing was completed we’ve seen an amazing 83 percent reduction in elk-vehicle collisions in this location.
Elk Don’t Like Mondays, Either
Highways have huge impacts on wildlife. Direct loss of animals in collisions is one part of the story. (Vehicles kill more than a million deer each year in the United States.) Another part is the “barrier effect” created by highways. When animals cannot get from wintering to summering areas, or from food to cover to water, a highway has become a barrier. This isolates wildlife populations, limits genetic interchange and affects the dispersal of young. The indirect impacts associated with highways go far beyond the actual roadway “footprint,” extending out as much as 10 to 15 times the width of the road.
Highways become barriers to wildlife, simply because of the number of cars using the road. The average daily traffic volume on state Route 260 surpassed 8,700 vehicles per day in 2003. It stands to reason that more animals should be killed on the days with the heaviest vehicle traffic, right? But most collisions between elk and vehicles occur on Mondays and Tuesdays, when traffic is lighter.
Why? Because GPS-collared elk crossed the highway most often on Mondays and Tuesdays. Though vehicle traffic decreases on these days, elk use increases. It seems elk avoid crossing on high traffic days like weekends, instead waiting to cross on the next low traffic days. This is why Mondays and Tuesdays are particularly bad days for elk (and motorists).
Animals Crossing — Slow Down!
In December 2006, Arizona activated its first-ever electric “wildlife crosswalk” on state Route 260 to reduce wildlife collisions that pose a risk to drivers and cost millions in property damage each year.
The system uses thermal infrared cameras that send images to sophisticated software normally used by the military to find targets. The software determines if the object could be a crossing deer or elk and sends signals to electronic warning signs, to capture the attention of motorists.
A 3-mile stretch of elk-proof fencing near the highway will funnel animals either to the crosswalk on the fence’s west end, or to the east, where there are underpasses.
Several partners — the Arizona Game and Fish Department, the ADOT, Federal Highway Administration, Tonto National Forest and contractors ElectroBraid Fence, Inc., and AZTEC Engineering, Inc. — developed the system.
Its success will be measured by monitoring the wildlife-vehicle collision rate, tracking elk with GPS telemetry, counting animals at the crosswalk with video cameras, and tracking and comparing average vehicle speeds before and after the warning signs are activated.
“If the data shows this project to be successful, the crosswalk concept could be considered elsewhere as a way of making other roads safer for wildlife and motorists,” says Steve Thomas of the Federal Highway Administration.
Making Highways Safer
ADOT has garnered well-deserved international acclaim for the state Route 260 construction project. In 2004 the Federal Highway Administration recognized the reconstruction project and associated research as an Exemplary Ecosystem Initiative for exceptional environmental stewardship.
Our research efforts are helping to increase the effectiveness of the underpasses and fencing that ADOT built as an investment in highway safety and wildlife permeability. Motorists who travel state Route 260 reap the benefits of this investment, traveling a highway that’s safer for people and wildlife alike. Eventually the lessons learned here will make more of Arizona’s highways safer.
Tips for Traveling Highways in Elk Country
- Be an alert driver.
- If possible, don’t travel after dark. Along state Route 260, nearly 30 percent of all elk-vehicle collisions occurred within one hour of sunset or sunrise.
- When traveling at night, stay within or below posted speed limits. Allow plenty of time to avoid animals.
- Be especially careful on Mondays and Tuesdays while traveling at night, though encounters with wildlife can occur on any day of the week.
- Be especially cautious when driving in the fall (September–November), as 49 percent of all annual collisions along state Route 260 occurred during these months. This period coincides with the elk breeding season and migration of animals toward wintering areas.
This article was published in the March-April 2007 issue of Arizona Wildlife Views magazine. To subscribe or give a gift, order online or call (800) 777-0015.
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