On November 25th, the first phase of construction began on Pima County’s first two wildlife underpasses on State Route 86! State Route 86 (SR 86) links Tucson to the Tohono O’odham Nation and lies within a critical corridor for wildlife movement. These underpasses were incorporated into an ADOT widening project on the Kitt Peak segment (milepost 132-137) and Santa Rosa segment (milepost 128-132) of SR 86. Milepost 130-138 has been identified as the Kitt Peak Wildlife Linkage and ranks as one of the 28 “highest priority” linkages of the 152 main wildlife linkages in the state due to its habitat value for mule deer, javelina, bighorn sheep, and the desert tortoise. It serves as a landscape-scale corridor among many “sky islands” along the Baboquivari Mountain range.
A pre-cast concrete arch being lowered by crane as part of the underpass construction.
These particular underpasses are being constructed by “dropping in” pre-cast concrete passage structures that will provide a safe and ample corridor for wildlife to pass below SR 86. Previously, narrow box culverts served as the only means for wildlife to move under the roadway; these narrow, constrained culverts were ineffective for wildlife passage and led to wildlife trying to cross SR 86 directly and often being hit and killed in the process. The new wildlife underpasses will increase wildlife and motorist safety by reducing wildlife vehicle collisions and the existing small culverts will be removed after the new underpasses are completed.
In January 2014, the next phase of underpass construction will begin, with the second half of each underpass being dropped in and continued paving of the new, widened roadway. Cameras will then be installed to monitor and document wildlife use of the underpass in the years ahead.
To further strengthen and re-connect this wildlife linkage, the Tohono O’odham Nation is pursuing federal funds to design a wildlife overpass west of the two underpasses to facilitate bighorn sheep movement. The Regional Transportation Authority’s Wildlife Linkages Committee, which recommended that the RTA fund construction of the two wildlife underpasses, will soon be reviewing a proposal from the Nation for construction of the overpass.
The construction of these underpasses is an accomplishment in ensuring connected ecosystems, healthy wildlife populations, and safety for both Sonoran Desert species and humans. We look forward to the completion and success of this project, and also to the construction of crossing structures on State Route 77 in the near future to preserve the Santa Catalina-Tortolita Mountain wildlife linkage! We will continue to post updates as both these projects move further along.
Click the links below to see a picture slideshow of the underpass construction: courtesy of Norris Dodd, ADOT Environmental Services, Wildlife Connectivity Coordinator.