The Wildlife Vehicle Collision Reduction and Habitat Connectivity Pooled Fund Study

 (PFS), TPF-5(358), seeks to identify cost-effective solutions that integrate highway safety and mobility with wildlife conservation and habitat connectivity.

Wildlife Vehicle Collision banner

Animal-Vehicle Collision Reduction and Habitat Connectivity
Pooled Fund Study – Literature review

Objective

The objective of this project is to identify cost-effective solutions to reduce wildlife vehicle collisions, for implementation by state departments of transportation.

Abstract

 Through a Transportation Pooled Fund, the WTI team will synthesize current knowledge from the US, Canada, and internationally; improve the cost benefit analyses of mitigation measures; field test improved designs and technologies; and coordinate and provide outreach to TPF partners and their stakeholders. Deliverables will include a Best Practices Manual for state DOTs.

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Incorporating wildlife passive use values in collision mitigation benefit-cost calculations

This project addresses the potential use of passive use economic values for wildlife to inform the mitigation of wildlife-vehicle collisions. Passive use, also known as non-use values, are the values individuals place on the existence of a given animal species or population as well as the bequest value of knowing that future generations will also benefit from preserving the species. This report provides a summary of the current literature of wildlife passive use value estimates and provides per-animal passive use values for selected species and populations. Additionally, an example of applying these values to a Montana road segment is outlined. Finally, a discussion of regional economic impacts of mitigation structure spending is outlined.

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Incorporating deer and turtle total value in collision mitigation benefit-cost calculations

Objective

This project will develop total value estimates for wildlife in a collision mitigation context. Total values include not only direct use such as hunting and viewing but also passive use values (biological conservation values).

Abstract

Wildlife-vehicle collisions and the associated damage and economic costs that result have been increasing in recent years . Damage caused by collisions with large ungulates (deer, elk, and moose) represent substantial costs in terms of vehicle damage as well as human injury and death. In ongoing efforts to mitigate these collision-caused damages and costs, there has been significant research aimed at identifying and estimating the extent of these collision costs. While the costs of adopting or constructing collision mitigation structures is generally easily measured, estimating the benefits of successful mitigation measures is less so. Factors necessary to understand the benefits of collision mitigation include considerations of the type of animal(s) involved in collisions, average costs associated with vehicle damage, human injury and death, as well as any lost value of the animal killed. In past studies the values associated with collision avoidance related to the injured/killed animals has been limited to easily identifiable direct use values of the animals, such as the value of the animal as hunted species. A second component of wildlife value heretofore omitted from the cost-benefit analysis of the cost-effectiveness of mitigation measures is passive use value for the animals. This project will develop total value estimates for wildlife in a collision mitigation context. Total values include not only direct use such as hunting and viewing but also passive use values (biological conservation values). The proposed research will focus on two specific species groups within the state of Minnesota: deer and turtles. Minnesota has been identified as a state providing a site with both widespread aquatic habitat and turtles, as well as being one of the states with the highest rate of damage from deer-vehicle collisions.

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A comparison of elk-vehicle collisions patterns with demographic and abundance data in the central Canadian Rocky Mountains.​

Objective

The objective of this project is to describe the patterns and processes that result in highway accidents involving elk, in order to provide transportation planners with the design of effective mitigation strategies in areas where elk is a dominant species.

Abstract

Since the mid-1970s, collisions between vehicles and large herbivores on the major roads in Canada’s mountain parks have been a concern for Parks Canada management. In response to increase collisions, Parks Canada initiated the construction of wildlife crossing structures and wildlife-exclusion fencing along the Trans Canada Highway (TCH) in the 1980s. These measures have been successful in reducing wildlife-vehicle collisions (WVCs), but WVCs involving elk (EVCs) in unmitigated areas remain a problem. EVCs contribute to 27% of wildlife related accidents in the Central Canadian Rockies, and are expected to increase as traffic volumes increase. The objective of this project is to describe the patterns and processes that result in highway accidents involving elk, in order to provide transportation planners with the design of effective mitigation strategies in areas where elk is a dominant species. The research team will explore age and sex patterns in EVCs, demography and condition of elk that were killed, seasonality of EVCs, EVC rates, traffic volumes, elk abundance, and other data to identify patterns and characteristics of these collisions.  

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Conservation Science and Practice

Improving Connectivity: Innovative Fiber-Reinforced Polymer Structures for Wildlife, Bicyclists, and/or Pedestrians-Final Report

Objective

The research will identify cost-sensitive and environmentally friendly fiber-reinforced polymer (FRP) materials and systems suitable for bridge superstructure elements that can be used for both wildlife and bike/ped crossings.  The project will seek to develop a system whereby the foundation and the FRP superstructure is interchangeable with different treatments of decking that specifically addresses the needs of wildlife, bicyclists and/or pedestrians. This research will reduce the impact of wildlife collisions in rural areas and improve motorist safety through the use of innovative FRP materials for the superstructure of the bridge. The modularity of FRP bridges will also make safer travel for bicyclists and pedestrians.

Abstract

Ecologists and engineers are constantly exploring new methods and adapting existing techniques to improve mitigation measures that increase motorist safety and wildlife species conservation. Crossing structures, combined with fences, are some of the most highly effective mitigation measures that are employed around the world due to their ability to not only reduce wildlife-vehicle collisions (WVCs) with large animals and increase motorist safety, but they also provide an additional benefit that other measures don’t, they help maintain habitat connectivity across transportation networks for many types and sizes of wildlife. Published research on bridge designs and materials for wildlife crossings is limited and suggests relatively little innovation has occurred. Given wildlife crossing structures are a critical contribution to highway mitigation strategies for reducing WVCs while also providing for habitat connectivity, species movement and migrations, the need for new, resourceful, and innovative techniques is warranted. This research explores the promising application of fiber-reinforced polymers (FRPs) to wildlife crossing structures. If FRP structural designs can meet all bridge specifications set by transportation agencies and prove to have less expensive life cycles, they will provide a new approach that is more efficient, more quickly deployed, lasts longer, requires less maintenance and is ultimately more adaptable than traditional materials. This project explores what is know about FRP bridge structures and materials that can be adapted for use in crossing structures over highways for wildlife and, by extension, for bicyclists and pedestrians as well.

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A Before-After-Control-Impact Study of Wildlife Fencing
Along a Highway in the Canadian Rocky Mountains

Wildlife exclusion fencing has become a standard component of highway mitigation systems designing to reduce collisions with large mammals. Past work on the effectiveness of exclusion fencing has relied heavily on control-impact (i.e., space-for-time substitutions) and before-after study designs. These designs limit inference and may confound the effectiveness of mitigation with co-occurring process that also change the rate of collisions. We used a replicated before-after-control-impact study design to assess fencing effectiveness along the Trans-Canada Highway in the Rocky Mountains of Canada. We found that collisions declined for common ungulates species (elk, mule deer and white-tailed deer) by up to 96% but not for large carnivores. The weak response of carnivores is likely due to combination of fence intrusions and low sample sizes. When accounting for background changes in collision rates observed at control sites, naïve estimates of fencing effectiveness declined by 6% at one site to 90% and increased by 10% at another to a realized effectiveness of 82%. When factoring in the cost of ungulate collisions to society as a whole, fencing provided a net economic gain within 1 year of construction. Over a 10-year period, fencing would provide a net economic gain of >$500,000 per km in reduced collisions. In contrast, control site may take upwards of 90 years before the background rates of collisions decline to a break even point. Our study highlights the benefits of long-term monitoring of road mitigation projects and provides evidence of fencing effectiveness for reducing wildlife-vehicle collisions involving large mammals. 

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Wildlife barriers at fence ends and at access roads, and wildlife jump-out design ​

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Wildlife jump-outs

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Long-term responses of an ecological
community to highway mitigation measures​

Wildlife exclusion fencing has become a standard component of highway mitigation systems designing to reduce collisions with large mammals. Past work on the effectiveness of exclusion fencing has relied heavily on control-impact (i.e., space-for-time substitutions) and before-after study designs. These designs limit inference and may confound the effectiveness of mitigation with co-occurring process that also change the rate of collisions. We used a replicated before-after-control-impact study design to assess fencing effectiveness along the Trans-Canada Highway in the Rocky Mountains of Canada. We found that collisions declined for common ungulates species (elk, mule deer and white-tailed deer) by up to 96% but not for large carnivores. The weak response of carnivores is likely due to combination of fence intrusions and low sample sizes. When accounting for background changes in collision rates observed at control sites, naïve estimates of fencing effectiveness declined by 6% at one site to 90% and increased by 10% at another to a realized effectiveness of 82%. When factoring in the cost of ungulate collisions to society as a whole, fencing provided a net economic gain within 1 year of construction. Over a 10-year period, fencing would provide a net economic gain of >$500,000 per km in reduced collisions. In contrast, control site may take upwards of 90 years before the background rates of collisions decline to a break even point. Our study highlights the benefits of long-term monitoring of road mitigation projects and provides evidence of fencing effectiveness for reducing wildlife-vehicle collisions involving large mammals. 

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Final Report, TPF-5(358) Task 1 Project Synthesis

Final Work In Progress

Best Practices Manual

Wildlife exclusion fencing has become a standard component of highway mitigation systems designing to reduce collisions with large mammals. Past work on the effectiveness of exclusion fencing has relied heavily on control-impact (i.e., space-for-time substitutions) and before-after study designs. These designs limit inference and may confound the effectiveness of mitigation with co-occurring process that also change the rate of collisions. We used a replicated before-after-control-impact study design to assess fencing effectiveness along the Trans-Canada Highway in the Rocky Mountains of Canada. We found that collisions declined for common ungulates species (elk, mule deer and white-tailed deer) by up to 96% but not for large carnivores. The weak response of carnivores is likely due to combination of fence intrusions and low sample sizes. When accounting for background changes in collision rates observed at control sites, naïve estimates of fencing effectiveness declined by 6% at one site to 90% and increased by 10% at another to a realized effectiveness of 82%. When factoring in the cost of ungulate collisions to society as a whole, fencing provided a net economic gain within 1 year of construction. Over a 10-year period, fencing would provide a net economic gain of >$500,000 per km in reduced collisions. In contrast, control site may take upwards of 90 years before the background rates of collisions decline to a break even point. Our study highlights the benefits of long-term monitoring of road mitigation projects and provides evidence of fencing effectiveness for reducing wildlife-vehicle collisions involving large mammals. 

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Permeability of large underpasses to wildlife: effects of ledges and addition of structure for facilitating movement of small mammals and herpetofauna (USGS)​

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Research to Inform Passage Spacing for Migratory Amphibians and to Evaluate Efficacy and Designs for Open Elevated Road Segment (ERS) Passages (USGS)

Evaluating the effectiveness of an elevated road segment to reduce road mortality and maintain connectivity between wetlands and uplands: Case study with the Yosemite toad (USGS)​

Abstract
This research was conducted to; 1) help inform the distances required between crossings to provide high permeability across roads for migratory amphibians (i.e., Yosemite toad), 2) to assess the permeability of a new passage design for amphibians and other small animal species, and 3) to provide engineering evaluation of this concept for primary roads and highways.
1) Although the sample size was low due to severe drought conditions in the last two years of the study and sampling constraints, we found similarities between the fence movement behavior of Yosemite toads and other migratory amphibians. Approximately 90% of toads were estimated to move 20 m or more along the fence, with an average distance of 46 m before “giving up”. These preliminary results suggest that passages spaced within 20m of one another along Yosemite toad migratory pathways are likely to provide connectivity to 90% of the population.
2) Initial results of passage permeability showed that the elevated road segment (ERS) crossing has a high potential to provide increased connectivity for Yosemite toads and a wide range of other amphibian, reptile, and small mammal species while greatly reducing road mortality.
3) The ERS concept designs, engineering evaluation and guidance document for primary roads and
highways provide a starting point for local and DOT engineers to design and build permanent ERS structure(s) to enhance the movement of small wildlife, particularly for, but not limited to, migrating amphibians over wide stretches of roadway.

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