The Loop 202 South Mountain Freeway is a 22-mile long new alignment completing the southwest portion of a loop freeway in Phoenix, Arizona. A portion of the project runs between the South Mountain Park/Preserve and the Gila River Indian Community (Community). Construction required cuts through two ridges of the South Mountains in this area. Drainage structures throughout this roughly 6 mile segment were designed to allow animal movement, with the focal species including deer and Sonoran desert tortoises and other reptiles. An Environmental Impact Statement was completed for the project and extensive coordination was conducted with the Community to address impacts to cultural and biological resources in the area. A contract for final design, construction and 30 years of maintenance of the alignment was awarded as part of a public-private partnership (P3). The contract was written with performance based requirements (technical provisions) rather than the typical specifications for a design-bid-build project.
Five multi-use crossings were designated in the freeway segment adjacent to the South Mountains. One crossing is shared with a regional county trail and another with a natural gas pipeline; the remaining three are designed for use by wildlife and access for Community members across the alignment. Wildlife exclusion fencing including buried mesh to exclude desert tortoises was installed throughout the 6-mile segment. Dumped riprap was not permitted to be used at the outlets of any culverts that cross the alignment in this freeway segment as well as at two additional culvert locations where higher reptile/amphibian roadkill numbers were observed prior to construction. Articulated block was used at many culvert outlets throughout the segment, a first for an ADOT project. Camera traps at the five multi-use crossings will be monitored for at least 3 years beginning in January 2021.
This presentation will address challenges encountered in the P3 process in both design and coordination as well as solutions and recommendations for future projects.