Arizona Department of Transportation
Comprehensive Approach to Wildlife Protection on State Route 260
SR 260 wildlife crossings by construction section (AGFD)
Pedestrian-Wildlife Underpass along the Christopher Creek Section showing the solar panel, and monitoring equipment. (Norris Dodd)
Elk Harem in Beaver Creek, AZ. (Robert Shantz)
Rocky Mountain elk attempting to cross 17 miles of Arizona's State Route 260 have a new lease on life, thanks to some innovative wildlife underpasses at accident "hot spots" along the route.
To improve safety on SR 260 from Payson to the Mogollon Rim, the Arizona Department of Transportation (ADOT) is upgrading the highway from a 2-lane route to a 4-lane divided highway. In the process, ADOT is collaborating with FHWA, the Tonto National Forest, the Arizona Game and Fish Department (AGFD), and other partners to build 17 sets of open-span bridges which will enable elk and other animals to safely cross under the highway to reach critical winter range, key watering sites and other habitat vital to their survival. Eleven of these structures are underpasses specifically constructed to provide wildlife passage, improving highway safety and habitat connectivity. Eleven of these structures are underpasses specifically constructed to provide wildlife passage, improving highway safety and habitat connectivity.
In addition to a set of massive bridges over 700-800 feet of Preacher Canyon, the first 2 sets of wildlife underpasses on State Route 260 span 115 feet and provide passage near Little Green Valley, a foraging area for elk, deer and other wildlife. Construction of 4 wildlife underpasses and 3 other bridged crossings at another section - Christopher Creek - -is nearly complete. Construction at another section - Kohls Ranch - began last summer and includes a major wildlife underpass and 2 sets of bridges over streams. These three sections exhibit some of the highest incidences of elk-vehicle collisions below the Mogollon Rim, averaging as many as six collisions per mile per year.
At Preacher Canyon, ADOT is using a comprehensive package of measures to keep elk off the highway, including wildlife-proof fencing, escape ramps, and one-way gates.
Experimental, low-maintenance "elk rock" (large angular rocks placed so close together elks cannot walk through them) is being used as an alternative fencing in some places on the Christopher Creek Section. Another innovative "fence" alternative is steep-cut side slopes. Both measures are helping funnel elk toward the underpasses and away from the highway.
The SR 260 underpasses are a "first" for Arizona, so the agency is cooperating with AGFD in thoroughly evaluating them for their effectiveness. What ADOT learns from the research will be applied to other highway upgrades.
The first research phase was initiated under a 2002 intergovernmental agreement between ADOT and AGFD, with AGFD focusing its research on the Preacher Canyon Section. In this "pilot study," AGFD biologists fitted 36 elk with Global Positioning Satellite collars to track the animals' movements up to and through the underpasses, as well as determining seasonal movements and where and when they cross the highway. Also, hidden, camouflaged video cameras allow researchers to assess passage rates, animal behavior, use of escape structures, traffic levels, and wildlife movement around the ends of the fencing. A second phase of research was recently begun by AGFD focusing on the new Christopher Creek Section. It will run through 2006.
AGFD's research has resulted in "adaptive management" strategies that have benefited both wildlife and ADOT. For example, at Preacher Canyon ADOT and AGFD learned that fences had to be longer than anticipated, and that elk prefer underpasses with natural sloped earthen sides to underpasses with unnatural concrete walls. Consequently, ADOT has extended fencing on various sections of the highway and redesigned the important underpass on the Kohls Ranch Section to eliminate concrete walls. On the Christopher Creek Section, AGFD found that "elk rock" had to be placed closer together to keep elk from walking through them.
The preliminary research on the 260 project is encouraging. Elk are using the underpasses, and though traffic volume has increased, the number of elk-vehicle accidents along the Preacher Canyon Section has not.
When AGFD's research is complete, biologists and transportation planners will have answers to questions like these: How many elk approaching an underpass actually use it? How many continue to the other end? How much fencing is necessary for highway safety? Are concentrated crossing zones created at the end of a fence? How can you make sure an underpass for elk will be effective? How far should fences extend to "intercept" a greater proportion of animals?
Once completed in a few years, the SR 260 project may represent one of the most comprehensive efforts in North America to reduce the risk of wildlife-vehicle collisions and enhance wildlife movement across and beyond the highway.
For more information, contact Norris Dodd, AGFD Research Biologist at email@example.com