I-25 South Gap Wildlife Monitoring Study

Details

• Creators:
  Kintsch, Julia ; Singer, Paige ; Telander, Andrew ; Knoedler, Riley ; Swenson, Jared ; Hanks, Britta ; Phelan, Joy
• Corporate Creators:
  ECO-resolutions, LLC
• Corporate Contributors:
  Colorado. Department of Transportation. Applied Research & Innovations Branch ; United States. Department of Transportation. Federal Highway Administration ; Colorado Parks and Wildlife
• Subject/TRT Terms:
  • Wildlife crossings
  • Animal vehicle crashes
  • Deer
  • Ramps
  • Ungulates
  • Roadside fauna
  • Fences
  • Traffic mitigation
  • Monitoring
  • Crash data
  More +
• Publication/ Report Number:
  CDOT-2025-08
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Colorado
• Corporate Publisher:
  Colorado. Department of Transportation
• Description:
  The Interstate 25 (I-25) South Gap project was a major highway expansion project aimed at alleviating congestion by adding lanes in each direction and incorporating safety enhancements. The Colorado Department of Transportation (CDOT) and its partners committed to designing a system of wildlife crossings - including five large bridge underpasses, wildlife exclusion fencing along 14.1 miles of the interstate, escape ramps, and wildlife guards - to reduce WVCs and improve habitat connectivity. This research evaluated the effectiveness of these mitigation investments using camera data and crash datasets from 2022 through 2024. The results from this study revealed that the wildlife infrastructure was one of the most effective components of the I-25 South Gap project in terms of crash reduction, yielding an 85% reduction in WVCs in the first two years post-construction. In addition, this study established the value of the five wildlife crossings for a wide range of wildlife, including the target species frequently involved in WVCs (deer and elk) and numerous other species, large and small. Variability in use and year-over-year increases in passage rates suggest wildlife continue to adapt and may increase their use as they become more accustomed to the crossing structures. This study notably included evaluation of purpose-built cover features designed to provide passage for small prey species, resulting in the detection of 17 species not otherwise captured by monitoring at the large underpasses, including two detections of the federally threatened Preble's meadow jumping mouse. This study also assessed other mitigation components, including wildlife guards, escape ramps, and the northern terminus of the wildlife exclusion fence. Overall, the I-25 South Gap wildlife crossings system met or exceeded most performance goals for wildlife use and collision reduction established at the outset of the study. The findings and recommendations from this research will guide future planning, siting, and design of wildlife mitigation systems, promoting safer, more connected landscapes along Colorado's busiest highways. Implementation: Several implementation recommendations are made related to maintenance, adaptive management, informing future wildlife mitigation projects, and future wildlife monitoring studies.
• Format:
  PDF
• Funding:
  22-HTD-ZA-00126
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/93562/dot_93562_DS1.pdf
• File Type:
  [PDF - 6.72 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:25d0bb58af1a3b7be705dca70ec587a35518e89e86f21679afa01619e4fcf061e0af67211877b85239cac0b115404d0c4d5a2dfae0b80ab3ff2671f6b0aa943f