Virginia has consistently been among the top 10 states for wildlife-vehicle collisions (WVCs), which make up over 6% of all reported collisions. Based on carcass removal studies, the number of WVCs that occur along roadways in the state are likely much higher than what is officially reported. Mitigation efforts can greatly reduce the financial burden and loss of life (both human and animals) caused by WVCs. Locating areas along major roadways where WVCs occur more often is an important first step to focus on effective, cost-effective mitigation efforts.
In 2020, the state of Virginia enacted the Wildlife Corridor Action Plan (WCAP) to “identify wildlife corridors, existing or planned barriers to movement along such corridors, and areas with a high risk of wildlife-vehicle collisions.” As part of this plan, VTTI researchers were tasked by VDOT to analyze WVC occurrences. The primary goal was to observe the occurrence rate of WVCs along roadways—if possible, specifically deer and bear collisions—and conduct a hotspot analysis of these occurrence rates. Other states that introduced similar legislation were studied to find what methods were used, and what could be applied to Virginia’s WCAP.
Datasets were sourced and compiled in ArcGIS, the primary of which was from the Virginia Roads database, to analyze the animal crash data between 2013 and 2020. The current crash report only differentiates by deer and other animals, but with the help of DMV personnel, data were searched by the keyword, “bear” in the publicly omitted comments section, which then made it possible to separately analyze bear crash data. Additionally, because the crash dataset is believed to be an underrepresentation of the true number of WVCs, carcass removal data sourced from VDOT’s HMMS database were used to create a supplementary layer, to help support the findings of the crash dataset.
Roadways were segmented by first using “Generate Points Along Lines” at 1 mile, then “Split Line at Point” to create the segment layer. WVCs were then spatially joined to the nearest road segment that occurred along each of these segments. WVC occurrence rates were created using a calculation to find the average rate (WVCs-per-mile, per-year) along each segment and were classified by top percentiles of the average occurrence rate. An “Optimized Hot Spot Analysis was run to confirm the findings of the road segmenting analysis, and to confirm WVCs are spatially clustered and not random. The conclusion of the analysis provided several heatmap layers to include in Virginia’s WCAP, both as interactive feature layers and as static images. These maps will be used to inform efforts made by the state of Virginia to mitigate WVCs along the chosen roadways. Possible improvements to this analysis would include allowing the reporting system to be more specific of different animal species, both wild and domesticated, as well as improving the carcass removal data system to be a more reliable source of information.
wildlife-vehicle collisions
Mitigation
hotspot analysis