Developing a Road Risk Model for Large Animal Crashes in Virginia: A Safe System Approach to Cost-Effective Safety Improvements

About the report

In 2020, the Virginia General Assembly enacted the Virginia Wildlife Corridor Action Plan (WCAP; Code of Virginia § 29.1-579), which directed the Virginia Department of Transportation (VDOT) and other state agencies to identify wildlife corridors and areas with a high risk of wildlife-vehicle collisions to prioritize wildlife crossing projects that improve driver safety and habitat connectivity. Elements of this directive align with VDOT’s adoption of the Safe System Approach, which emphasizes proactive road design and management to reduce crash risk. Meeting both WCAP and roadway safety objectives requires reliable tools to identify roadway segments where wildlife crashes are most likely to occur. However, police-reported crash data substantially underrepresent large animal crashes and do not account for road and landscape factors that influence crash risk.

The study developed a predictive large animal road risk model to identify Virginia road segments with elevated risk of white-tailed deer and black bear crashes. The model integrates police-reported crash data with road characteristics, traffic volumes, land cover, and other variables to produce crash risk estimates across the road network. To address crash underreporting, correction factors were evaluated using additional crash data sources, and these factors were incorporated into model outputs and subsequent benefit-cost analyses. A benefit-cost calculator spreadsheet was developed to support the evaluation of the appropriate level of investment based on expected safety benefits.

Model performance evaluation demonstrated that a small proportion of roadway segments identified as highest risk account for a disproportionately large share of reported deer and bear crashes, including crashes that occurred after the study period on which the model was developed. This occurrence indicates that the model is effective at targeting high-risk roadway segments. The large animal road risk model and supporting benefit-cost approach will contribute to the WCAP prioritization process and will supplement VDOT safety efforts by improving evaluation of large animal crash risk, the cost-effectiveness of safety countermeasures, and decision-making that is consistent with VDOT safety evaluation practices. It is recommended that VDOT (1) provide the deer and bear road risk model and accompanying report to the team developing the next version of the WCAP for use in wildlife crossing project prioritization and (2) incorporate the study findings and deliverables into its safety evaluation and reporting practices to support roadway risk assessment and benefit-cost analyses.

Supplemental materials can be found at https://library.vdot.virginia.gov/vtrc/supplements.

_{Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.}

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