The National Academies

NCHRP 25-27 [Completed]

Evaluation of the Use and Effectiveness of Wildlife Crossings

  Project Data
Funds: $568,996.78
Research Agency: Utah State University
Principal Investigator: John A. Bissonette
Effective Date: 6/1/2004
Completion Date: 12/31/2007


Every year, the costs of personal injuries and property damage resulting from animal/vehicle collisions are considerable. Various means have been employed to mitigate these collisions, with varying degrees of success. In recent years, highway agencies have placed a growing emphasis on protecting the environment. While many smaller species of animals do not pose a threat to vehicles through collisions, they experience significant habitat loss and fragmentation as a result of roadway alignments. Transportation corridors limit the natural movement of wildlife, affecting individual species and ecosystems. There has been considerable research on the provision of wildlife crossings, but there is a lack of data on their effectiveness and on the methods most effective for a particular species in a particular landscape. It also appears that crossings may work well for one species but not for others. An international scan on wildlife habitat connectivity documented various strategies and designs used in Europe to improve the connectivity of wildlife habitats. Developing successful designs, methods, and strategies to make roadways more permeable to wildlife is but one aspect of managing highways to avoid or minimize affects to the natural environment and maintaining safety for motorists. There is a need to provide state DOTs with guidance on the use and effectiveness of wildlife crossings to mitigate habitat fragmentation and reduce the number of animal/vehicle collisions on our roadways.


The objective of this project was to develop guidelines for the selection (type), configuration, location, monitoring, evaluation, and maintenance of wildlife crossings.

Accomplishment of the project objective involved the following tasks.


Phase I (1.) Analyze, describe, and critique pertinent domestic and international research, based on applicability, conclusiveness of findings, and usefulness for the accomplishment of the project objective. Include both completed research and research in progress. (2.) Conduct a survey of current domestic and international practices in the use of wildlife crossings. This survey should update but not duplicate information collected for NCHRP Synthesis 305: Interaction between Roadways and Wildlife Ecology. (3.) Identify and prioritize gaps and needs in the current body of research and practices, and determine where additional research and field evaluation will be required in order to achieve the project objectives. (4.) Within the time and budget constraints of the project, develop a plan for new research and field evaluation to fill the gaps identified in Task 3. In Phase II field testing, it is anticipated that there may be a need to partner with federal, state, or local agencies to evaluate existing wildlife crossings or to install and evaluate new crossing types. (5.) Prepare a draft outline and a recommended format for the proposed guidelines. The outline should be presented in sufficient detail to provide an indication of the structure and decision process that will be incorporated into the guidelines. At the conclusion of the project, the final guidelines will be provided both in print format and as an electronic decision tool. It is expected that the guidelines will include, but not be limited to, the following:

  • Methods to identify species impacted by roadways and methods to determine the impacts on their population.
  • Methods to quantify the impacts of animal-vehicle collisions.
  • Methods for determining the location of problem areas.
  • Crossings for new roadway alignments and realignments as well as for retrofit of existing roads and structures.
  • Selection and configuration of crossing types appropriate for specific species.
  • Approaches to address specific species at problem locations and ecosystem-level approaches.
  • Development of measures of effectiveness.
  • Cost-benefit and cost-effectiveness considerations.
  • Secondary, cumulative, or other impacts resulting from installation of wildlife crossings (e.g., modified wildlife movement patterns, construction impacts, or changes to local drainage patterns).
  • Other mitigation treatments to keep wildlife off the roadway.
  • Passive and active warning signals to alert motorists of crossings.
  • Long-term maintenance strategies and requirements.

(6.) Submit an interim report, within 6 months, to document Tasks 1 through 5 for review by the NCHRP. The contractor will be expected to meet with the NCHRP panel approximately 1 month later. A decision on whether or not to proceed with any or all of proposed Phase II activity will be made by the NCHRP. The contractor shall not begin work on Phase II without NCHRP approval.

Phase II (7.) Conduct the research and field evaluation outlined in the Task 4 plan as approved by the NCHRP. (8.) Based on the results of Tasks 1 through 7, develop draft guidelines, and the prototype electronic decision tool. (9.) Submit a second interim report, within 24 months of contract execution, to document the results of Tasks 7 and 8. The contractor will be expected to meet with the NCHRP panel approximately 1 month later. (10.) Based on NCHRP review of the second interim report, finalize the guidelines and the electronic decision tool for the selection (type), configuration, location, monitoring, evaluation, and maintenance of wildlife crossings. (11.) Submit a final report that documents the entire research effort and includes the Task 10 guidelines and the decision tool as stand-alone products. In addition, provide a companion executive summary and PowerPoint presentation that outlines the background, methodology, and findings of the research.

Status: Completed.   

Product Availability: NCHRP Report 615: Evaluation of the Use and Effectiveness of Wildlife Crossings.  The contractor's  final report is available as an Adobe PDF document . 

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