Mortality Effects of Continuous Concrete Highway Median Barriers on Wildlife

Focus Area

Wildlife & Ecosystems


Natural Resources







Research Idea Scope

TERI Administrator Note (March 2008) Research Completed:
HIGHWAY MEDIAN IMPACTS ON WILDLIFE MOVEMENT AND MORTALITY – State of the Practice Survey and Gap Analysis, CalTrans, 2006

Problem Statement:

Along Interstate 5 (I-5) in northern Shasta and southern Siskiyou counties, California, Caltrans has installed 12 miles of continuous concrete median barrier with no provisions for animal crossing. In addition, 20 miles of additional barrier are planned, connecting on the southern end of this existing barrier. There is a high number of animals (predominantly deer) killed while crossing I-5 before any median barrier was installed and it is anticipated that this mortality rate will increase with the new barrier. This baseline mortality is based on Caltrans and Department of Fish & Game biologist observations and on a 1970-1980 Caltrans research project on animal road kill in northern California. Caltrans will incorporate mitigation for the planned 20 miles of barrier, which will include small openings and changes in signing to alert motorists. Also, seven small openings will be retrofitted into the existing 12 miles of median barrier.
Proposed Research:
A study that collects baseline data (animal kill) for the 20 miles of yet-to-be installed and for the existing barrier prior to retro-fit with openings. Subsequently, follow up this baseline data with one to three years of post-barrier/retrofit to provide valuable information regarding the impacts of barrier and the effectiveness of this type of mitigation. This information could help design future projects that reduce animal kill and increase the success of mitigation.

Suggested By

2002 Research Needs Conference Idea Daniel Whitley Associate Environmental Planner (Biologist) Dept. of Transportation

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