Performance Evaluation of a Highway Retrofit for Wildlife: I-17 Munds Park to Woods Canyon

Interstate-17 is the primary route connecting Phoenix to Flagstaff and is the main artery serving northern Arizona and supporting the transport of goods along I-40 to the east and west. Interstate-17 is traveled by millions of tourists each year visiting area national parks (NP) and recreation areas, including the Grand Canyon NP, Petrified Forest NP, Sunset Crater National Monument, Glen Canyon Recreation Area, etc. As Arizona continues to grow, traffic on I-17 will also increase. This stretch of highway is considered one of the highest elk-vehicle collision areas in Arizona; the majority of these collisions (97%) occur between Stoneman Lake Road and Flagstaff. Further, I-17 is considered a very high volume highway, and as such, is predicted to pose a significant barrier to wildlife (Mueller and Berthoud 1997). Wildlife passage structures have shown benefit in promoting passage for a variety of wildlife species, have reduced the incidence of wildlife-vehicle collisions, and yielded substantial economic benefit (Dodd et al. 2007). As such, the Arizona Department of Transportation (ADOT) has committed funds to support a SAFETEA-LU project that will link existing bridges and transportation interchanges to reduce elk-vehicle collisions and promote permeability across the I-17 corridor. This represents a tremendous commitment on the part of ADOT and warrants thorough evaluation to assess the efficacy of this fencing in promoting permeability, particularly since few retrofit opportunities have been attempted and can lead to future cost-savings and accident reductions for many highways throughout Arizona and the rest of the nation. Research here will also complement that ongoing on SR 260, I-17, US 89, SR 64, and Interstate 40 and provide valuable insights into wildlife-highway interactions for a range of wildlife and approaches to mitigate highway and traffic impacts. This project will assess: (1) Elk movement and highway crossing patterns, including calculating permeability across the highway after fencing is constructed to compare to movement patterns and permeability evaluated during pre fencing research; (2) Movements of wildlife through the bridges and transportation interchanges; and 3. Wildlife-vehicle collision patterns following implementation of fencing.