Wildlife Crossing Guards and ROW Escape Mechanisms

Collisions with large ungulates (like deer, elk, and bighorn sheep) pose a safety concern for motorists on highways. In an effort to reduce ungulate-vehicle collisions in the right-of-way (ROW), the Arizona Department of Transportation (ADOT) installs ungulate-proof fencing to limit access to the ROW and funnel ungulates to new or existing structures. This fencing has escape mechanisms (jump-outs or slope jumps -- to allow wildlife already on the ROW an opportunity to leave), and wildlife crossing guards (WCGs) to allow vehicles to enter or leave the ROW while limiting wildlife passage. However, minimal empirical data exists on the effectiveness of the escape mechanisms and WCGs in keeping ungulates from the ROW. Currently ADOT installs WCGs where roads intersect the ungulate-proof fencing. Types of WCGs currently include traditional (single) cattle guards, double-deep cattle guards, painted stripes, and, more recently, electrified mats. Many state departments of transportation (DOTs), including ADOT, install costly double-deep cattle guards despite lack of evidence that they are more effective compared to the other WCG types. Electrified mats have been implemented in several states (Arizona, Utah, California, New Mexico, Alaska and others) but similarly have not been fully tested against other WCG types. In the event large ungulates gain access to the ROW, opportunities to allow them to escape are warranted. Generally, ADOT has used three methods to accommodate escape: one-way gates, slope jumps, and jump-outs. Early research along SR 260 and information from other states indicate that one-way gates are relatively ineffective. Jump-outs seem to fare somewhat better while costing less, and ADOT's AGFD-designed slope jumps hold even more promise because of the idea that ungulates would more easily jump downhill over the slope jumps. Though many of these slope jumps now exist, information on their effectiveness is also limited. Despite evidence that jump-outs likely are the best option for allowing ungulate escape from the ROW, little is known about appropriate designs for different ungulate species. Early research along SR 260 began the effort to explore the effectiveness of jump-outs on elk and provided valuable insight for future planning processes; however, the number of jump-outs available for monitoring during those studies was relatively limited. Recently, ADOT installed a mix of different jump-outs that includes expensive concrete-wall types and less expensive gabion-basket types. Jump-outs are now numerous throughout the state and occur in areas with elk, deer, and bighorn sheep. Further research is needed to determine effective heights and designs for these species. Arizona, seen as one of the worldwide leaders in road ecology, has an opportunity to further explore effective escape mechanisms (given their current large numbers along SR 260, I-17, and US 93) for various species.