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Development of Reptile/Amphibian Road Crossing Design Options for National Park Service

Project #: 4W9989
Start Date: 09/15/2022
End Date: 12/31/2024
Status: Current

Significant amphibian declines have occurred in protected areas not subjected to obvious changes in habitat (e.g., national parks, wildlife refuges, and wilderness areas) to an extent that these declines should be considered a potential environmental crisis. Because many reptiles and amphibians use both aquatic and terrestrial habitat for breeding, development, foraging, and overwintering, they require high levels of connectivity within and between aquatic and terrestrial habitats. As a result, amphibians and reptiles are particularly sensitive to the negative effects of roads, such as habitat fragmentation and vehicle collisions, because of their slow movements, small size, and propensity to travel long distances. They also do not avoid roads, and, as ectotherms, snakes and lizards are often attracted to sun-warmed pavement. Deaths due to vehicles collisions are causing detrimental population effects by reducing genetic diversity and population abundance.


This project will develop road crossing and barrier fencing system designs that can be customized for specific species of concern at any given location in the United States. This work will focus on requirements gathering, literature review, field assessments, stakeholder outreach, developing minimum design requirements, assessment of current designs, and developing conceptual designs on behalf of the National Park Service. The follow-on research project will focus on developing detailed designs, constructability review, and evaluative monitoring. A number of crossings constructed in next few years will be selected for long-term monitoring program.


  • Marcel Huijser
    Marcel Huijser