An exploration of the high cost of wildlife-vehicle collisions and the
many challenges to transforming the U.S. road network.
Documentation of the safety, ecological, economic, and social benefits
anticipated to accrue from investing in highway crossings for wildlife,
including enhanced motorist safety, reduced wildlife mortality, and improved
Identification of policy and funding improvements and activities that
would further support the deployment of crossing structures.
Recommendations on how to build upon successful efforts to reduce
wildlife-vehicle collisions already underway at the federal, state, local, and
WTI Road Ecology Program Rob Ament served as one of the editors for the report, and WTI Research Scientists Tony Clevenger, Marcel Huijser, and Angela Kociolek are contributing authors.
CITATION: Ament, R.; Jacobson, S;
Callahan, R.; Brocki, M., eds. 2021. Highway crossing structures for wildlife:
opportunities for improving driver and animal safety. Gen. Tech. Rep.
PSW-GTR-271. Albany, CA: U.S. Department of Agriculture, Forest Service,
Pacific Southwest Research Station. 51 p.
The New York Times has posted an online feature article highlighting excellent footage of wildlife using various forms of highway crossings. “How Do Animals Safely Cross a Highway? Take a Look” includes footage of a herd of antelope crossing a highway in Wyoming; moose, bear, wolves and deer using crossings in Utah; and an alligator and panther using underground passages in Florida. WTI Road Ecologist Marcel Huijser was interviewed for the article in which he discusses that despite the upfront installation costs, wildlife crossings yield significant safety and conservation benefits that save money in the long run. Whisper Camel-Means, a tribal wildlife program manager who collaborated with WTI on US 93 wildlife crossing projects in Montana, was also interviewed for the article.
Roads can be dangerous for California’s reptiles and amphibians, but a five-year study and new video show that there are effective strategies to help these animals cross roads safely.
The California Department of Transportation (Caltrans) released the results of the study this week in a comprehensive, evidence-based best practices guide that explains approaches and techniques for minimizing the impact of roads on fragile and diminishing habitats and species, including frogs, toads, salamanders, turtles, lizards and snakes.
practices guide is the first of its kind for amphibian and reptile management
and conservation near California roads.
“It is no
longer a case of putting a few pipes and fences into the ground with a ‘fit and
forget’ approach,” said Tom Langton of Herpetofauna Consultants International,
Ltd., primary author on the guidance document. “This guide offers resource
managers in California opportunities and a clear plan to improve existing
crossings and build new ones to better standards where they are most needed. The guidance should be valued in
other states with similar wildlife-road issues and at the international level,
and amphibian species must cross roads to reach essential breeding and foraging
habitat, are slow moving or
are too small for drivers to see and avoid. Snakes and lizards may also be attracted to paved roads
that typically absorb and retain heat.
All these behaviors put them at high risk of vehicle collisions.
have a responsibility to maintain the highway system in a way that doesn’t
impede or disrupt wildlife, including the movement of California’s threatened
and endangered reptile and amphibian species,” said Caltrans Director Toks
Omishakin. “This study allows us to analyze feasible and
effective ways Caltrans can use ecologically-minded design to minimize
impacts on these wildlife populations.”
transportation agencies and wildlife managers have installed structures to
help amphibians, reptiles and other small animals cross highways safely, such
as tunnels under roads or barrier fencing.
agencies have made significant investments in these structures for many years,
there has been little research into how effective they are,” said Dr. Robert
Fisher, a U.S. Geological Survey (USGS) supervisory ecologist involved in the
study. “Management guidance informed by science is needed to help ensure this
critical infrastructure is safe for sensitive species.”
With these concerns in mind, the goals of the
collaborative project were to address this information gap using a logical
framework and to help transportation agencies like Caltrans plan barrier and
crossing structures more effectively.
To help Caltrans determine which reptile and amphibian
species to prioritize, USGS scientists created a ranking system for more than
160 species and sub-species, based on their vulnerability to road dangers.
Turtles, tortoises and snakes dominated the highest risk category. USGS also
developed a mapping system to allow Caltrans to easily find where the ranges of
high-risk species overlap with California highways and statewide conservation
efforts. Species ranked high and very-high risk of negative road-related
impacts include desert tortoise, California red-legged frog, sierra newt and
red diamond rattlesnake, among others.
Then, in a series of field experiments, the USGS
scientists investigated how reptiles and amphibians interact with different
types of fencing, how far high-risk migrating amphibians move along road
barrier fencing before “giving up” or finding a passage, and the effectiveness
of turnarounds at fence ends.
“We were happy to find that turnarounds at barrier fence ends were largely effective in changing the trajectory of many species to help lead them back toward a passage,” said Cheryl Brehme, the USGS project lead. A new video by USGS shows a California tiger salamander successfully make it to an underground crossing after being guided by one of these turnarounds.
“The elevated road-segment is really exciting,” said
Brehme, “because it can be made to any width and length enabling reptiles,
amphibians and other small wildlife species to freely move back and forth
across wide stretches of roadway.”
Caltrans used the results of these combined studies to produce the best management practices guide, which will inform the work of district biologists and engineers and will likely be useful to many other organizations involved in the planning and construction of transportation infrastructure. USGS has also released a comprehensive reportof its studies in conjunction with the new guidance document.
emphasizes that different landscapes – and different species – need a range of
solutions, and the needs of different species and their numbers will influence
positioning and sizes.
“Planning for smaller rare species calls for designs that take into account the sensitivities and needs of these understudied and often forgotten species” said Dr. Tony Clevenger of Western Transportation Institute, who led the development of the best management practices guide. The best practices guide was produced for Caltrans by the Western Transportation Institute of Montana State University with Herpetofauna Consultants International, Ltd and is based on existing knowledge and foundational studies by the U.S. Geological Survey Western Ecological Research Center.
California Department of Transportation (Caltrans)
Amy Bailey, Supervising Environmental Planner
Public Policy magazine In These Times recently interviewed WTI Road Ecologist Marcel Huijser for an in-depth article on wildlife crossings. “Toward a World Without Roadkill” highlights efforts by residents and local organizations near Great Smoky Mountains National Park to reduce the rising number of bears, deer, and elk being hit by vehicles on Interstate 40. Marcel discusses how mitigation efforts such as wildlife crossings can have significant conservation, safety, and economic benefits.
On February 25, Road Ecology Program Manager Rob Ament was a guest on Top of Mind with Julie Rose, a BYU Radio program. For a feature segment on wildlife crossings, Rob discussed how crossing structures are designed, how they make roads safer for both animals and motorists, and where the newest structures are being built, both in the U.S. and globally. The full Wildlife Crossings interview is available to stream on the BYU Radio website.
In 2018, the Utah Department of Transportation completed the state’s largest wildlife crossing, which traverses six lanes of traffic on Interstate 80. The crossing structure made the news again last week, when research footage captured deer, moose, elk, bears, bobcats and a variety of smaller mammals using the bridge. In news coverage by Smithsonian Magazine, “Animals are Using Utah’s Largest Wildlife Overpass Earlier Than Expected,” WTI Road Ecologist Rob Ament is quoted regarding the high percentage of collision reductions that typically occur after the installation of crossing structures. Rob’s quote is also included in a similar article by Nature World News.
The U.S. Forest Service
has released a new report authored by wildlife crossing experts from WTI, ARC
Solutions, and other partner research organizations, which compiles key
guidance information that may lead to the installation of more wildlife
structures are one of the most effective means of reducing animal-vehicle
collisions on highways, while facilitating essential animal movement across the
landscape. Yet the widespread implementation of such structures, especially
wildlife overpasses, has been hindered by cost concerns. In 2014, WTI hosted a
workshop in partnership with ARC Solutions and prominent wildlife crossing
experts from Canada and the United States to determine whether there are design
parameters and construction techniques that could be added, changed, or
adjusted to reduce costs, while maintaining or improving the effectiveness of
during the workshop were developed into specific strategies. This document presents 32 potential cost
savings considerations, which were consolidated into three categories:
design and construction
procurement, delivery method, and cost accounting considerations
Citation: McGuire, Terry M.; Clevenger, Anthony P.; Ament, Robert; Callahan, Renee; Jacobson, Sandra, eds. 2020. Innovative strategies to reduce the costs of effective wildlife overpasses. Gen. Tech. Rep. PSW-GTR-267. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station.
On October 20, ARC Solutions presented former WTI Director Steve Albert with a Lifetime Road Ecology Leadership Award in recognition of his enduring legacy in making our nation’s roads safer for both people and wildlife.A not-for-profit network working to promote leading-edge solutions to improve human safety, wildlife mobility and landscape connectivity, ARC celebrated Steve’s leadership, his encouragement, and his creativity, first as a co-founder of the ARC International Wildlife Crossing Infrastructure Design Competition and then as an original member of the ARC Steering Committee. Executive Director Renee Callahan highlighted a variety of successes supported and inspired by Steve during his decade-plus tenure with ARC, including:
“Winning 4 Wildlife” – Aimed at introducing middle school students to the concepts of safe passage and the need for creative wildlife-friendly solutions to make our highways safer, this curriculum was co-developed by three Montana teachers as part of WTI’s Innovative Transportation Systems Research Engagement for Teachersprogram in 2018.
WVC Reduction and Habitat Connectivity Pooled Fund Study – ARC partnered with the State of Nevada to launch a pooled fund study on WVC Reduction and Habitat Connectivity. Study members, including Alaska, Arizona, California, Iowa, Michigan, Minnesota, New Mexico, Oregon, Washington, the Ontario Ministry of Transportation and Parks Canada, have since committed $1.275 million in research funds to identify cost-effective solutions to integrate highway safety and human mobility with wildlife conservation and habitat connectivity. WTI Road Ecologist Marcel Huijser is leading a team of researchers conducting the research task to identify and evaluate cost-effective strategies.
Fiber-Reinforced Polymer Crossing Structure – In one of the research projects under the Pooled Fund Study, WTI is teaming with ARC Solutions, Ryerson University and the California Department of Transportation to explore design-based opportunities to build North America’s first fiber-reinforced polymer (FRP) wildlife crossing in Siskiyou County, CA. A highly-versatile materialthat is durable, modular, and virtually maintenance free, FRP is widely used in Europe for bike-ped infrastructure and promises to be a game-changer in the construction of the next-generation of wildlife infrastructure in the U.S.
During the ceremony, ARC presented Steve with a keepsake card and commemorative print by renowned wildlife photographer Joe Riis depicting mule deer crossing a roadway within the Greater Yellowstone Ecosystem. Family, friends, and colleagues joined in the festivities by sharing personal and professional tributes illustrating Steve’s exceptional leadership within the field of road ecology. ARC is fiscally sponsored by the Center for Large Landscape Conservation in Bozeman, MT. To learn more about ARC’s work, please visit arc-solutions.org. To learn more about WTI’s research in this area, visit the WTI Road Ecology webpage.
WTI Road Ecologist Rob Ament is featured in a recent issue of Time Magazine for Kids. A feature article called “Safe Travels” describes the large number of animals that are killed in roadway collisions each year, and how wildlife crossing structures work to protect animals as they move across their habitats. Rob discusses successful designs – like the crossing structures in Banff National Park – and how they are models for new efforts around the world, including a project he is working on in Kaziranga National Park in India.
Time for Kids is a weekly magazine for elementary school children. It offers age appropriate learning material for students and is designed to complement curriculum.