Research for the AASHTO Committee on Environment and Sustainability. Task 113. Road Passages and Barriers for Small Terrestrial Wildlife: Summary and Repository of Design Examples

Since the Nutty Narrows squirrel bridge was constructed in Longview, Washington in 1963, a wide range of projects have been implemented by state DOTs, local governments, and non-governmental organizations to remedy situations with high levels of road-related mortality for smaller wildlife, reptiles and amphibians. These projects include incorporation of measures into new roads, retrofits of existing infrastructure, and addition of infrastructure specifically for wildlife use. Many of these projects have also implemented post-construction monitoring to evaluate effectiveness. However, many of these projects are not known beyond the local area or state where they were constructed. As a result, the designs and lessons learned from their implementation are not available to inform current projects. The purpose of this study is to gather and summarize existing information on crossing structures, passages, and exclusion barriers for small terrestrial mammals, reptiles, and amphibians. The information will be organized in a repository of design examples, plan sheets, and case studies of successes and lessons learned for a representative selection of projects.


  • English


  • Status: Completed
  • Funding: $125000
  • Contract Numbers:

    Project 25-25, Task 113

  • Sponsor Organizations:

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Hartell, Ann

  • Performing Organizations:

    Louis Berger and Associates, Incorporated

    100 Halsted Street
    East Orange, NJ  United States  07019

    Western Transportation Institute

    Montana State University, Bozeman
    P.O. Box 174250
    Bozeman, MT  United States  59717-4250

    Eco-Kare International

    Peterborough, Ontario  Canada 
  • Principal Investigators:

    Huijser, Marcel

    Gunson, Kari

  • Start Date: 20180320
  • Expected Completion Date: 20190919
  • Actual Completion Date: 20190919

Subject/Index Terms

Filing Info

  • Accession Number: 01659861
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 25-25, Task 113
  • Files: TRB, RIP
  • Created Date: Feb 12 2018 10:22PM