Scholarly Work - Western Transportation Institute

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    Do wildlife crossing structures mitigate the barrier effect of roads on animal movement? A global assessment
    (British Ecological Society, 2024-01) Soanes, Kylie; Rytwinski, Trina; Fahrig, Lenore; Huijser, Marcel P.; Jaeger, Jochen A. G.; Teixeira, Fernanda Z.; van der Ree, Rodney; van der Grift, Edgar A.
    The widespread impacts of roads on animal movement have led to the search for innovative mitigation tools. Wildlife crossing structures (tunnels or bridges) are a common approach; however, their effectiveness remains unclear beyond isolated case studies. We conduct an extensive literature review and synthesis to address the question: What is the evidence that wildlife crossing structures mitigate the barrier effect of roads on wildlife movement? In particular, we investigated whether wildlife crossing structures prevented an expected decline in cross-road movement, restored movement to pre-construction conditions, or improved movement relative to taking no action. In an analysis of 313 studies, only 14% evaluated whether wildlife crossing structures resulted in a change in animal movement across roads. We identified critical problems in existing studies, especially the lack of benchmarks (e.g. pre-road, pre-mitigation, or control data) and the use of biased comparisons. Wildlife crossing structures allowed cross-road movement in 98% of data sets and improved movement in ~60%. In contrast, the decline of wildlife movement was prevented in fewer than 40% of cases. For most structure types and species groups there was insufficient evidence to draw generalisable conclusions. Synthesis and Applications: The evidence to date suggests that wildlife crossing structures can mitigate the barrier effect of roads on wildlife movement, but in many cases have been poorly implemented or evaluated. The most supported measures were the addition of ledges and vegetation cover to increase movement for small mammals; underpasses to prevent the decline in movement of ungulates following road construction; and improving road-crossing for arboreal mammals using canopy bridges and vegetated medians. We strongly recommend that future use of crossing structures closely adheres to species-specific, best-practice guidelines to improve implementation and be paired with a thorough evaluation that includes benchmark comparisons, particularly for measures and species that lack sufficient evidence (e.g. invertebrates, amphibians, reptiles, birds, and overpasses).
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    West-Wide Study to Identify Important Highway Locations for Wildlife Crossings
    (Western Transportation Institute, 2023-06) Paul, Kylie; Faselt, Jamie; Bell, Matthew; Huijser, Marcel P.; Theobald, David; Keeley, Annika; Ament, Robert
    Wildlife-vehicle collisions (WVCs), reduced ecological connectivity, and associated impacts to wildlife and humans are widespread problems across road networks, but mitigation measures like wildlife crossings1 that can address those problems are often considered expensive. This effort aims to support transportation agencies, wildlife agencies and other decision-makers by identifying important road segments where cost-effective wildlife crossings can be deployed to address motorist safety, ecological connectivity and other conservation values across the eleven U.S. western conterminous states of Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.
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    US-191/MT-64 Wildlife & Transportation Assessment
    (Center for large Landscape Conservation, 2023-11) Fairbank, Elizabeth; Penrod, Kristeen; Wearn, Anna; Blank, Matt; Bell, Matthew; Huijser, Marcel; Ament, Rob; Fick, Damon; Breuer, Abigail; Hance, Braden
    The US Highway 191 (US-191)/Montana Highway 64 (MT-64) Wildlife & Transportation Assessment (the “Assessment”) improves understanding of the issues affecting driver safety, wildlife mortality, and wildlife movement along the major routes that connect Yellowstone National Park, the Custer Gallatin National Forest, and other public lands to the growing population centers of Bozeman, Big Sky, and nearby communities in Southwest Montana. By engaging personnel from multiple federal, state, and local agencies along with key stakeholders to examine problems and possibilities through the lens of spatial ecology, the US-191/MT-64 Wildlife & Transportation Assessment brings new insight into the impact of two major roads that unite local communities yet divide the landscape and natural habitats. The information included in this report should inform and support area communities and agency decision-makers to select and pursue wildlife accommodation options. With the passage of the Infrastructure Investment and Jobs Act of 2021, significant funds for wildlife accommodation measures are available nationwide on a competitive basis. The US-191/MT-64 Wildlife & Transportation Assessment better equips part of Southwest Montana’s gateway to Yellowstone National Park to take advantage of new funding opportunities.
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    Exploration of opportunities to address the impacts of roads and traffic on wildlife around Rocky Flats National Wildlife Refuge
    (Western Transportation Institute, 2023-11) Huijser, Marcel P.; Begley, James S.
    Rocky Flats National Wildlife Refuge (“the Refuge”) in Colorado near Denver, Colorado, has a history (1952-1 989) of producing components for nuclear weapons. The current goal for the area is “to restore and preserve the native prairie ecosystems, provide habitat for migratory and resident wildlife, conserve and protect habitat for Preble’s meadow jumping mouse, and provide research and education opportunities”. The grasslands of the Refuge are surrounded by busy roads to the west (Hwy 93, 18,000 AADT), north (Hwy 128, 4,200 AADT) and east (Indiana St. 7,000 AADT), and there are houses and associated roads on its southern boundary. Other open space with non-motorized trails and protected areas with predominantly grassland are to the west, north and east. Large ungulates, including mule deer, elk, and moose cross the roads. This results in large ungulate -vehicle collisions and the roads also represent a barrier to the movements of animals. Creek crossings under the roads are a concern as they are likely a barrier for species dependent on riparian habitat, including the Preble’s meadow jumping mouse. The objectives of the current project were to 1. Formulate measures that reduce collisions with large wild mammals, and 2. Formulate measures that improve connectivity across roads for large wild mammal species and one small mammal species in specific, the Preble’s meadow jumping mouse. We suggest large open span bridges at creek crossings (for deer, moose, black bear, mountain lion, and Preble’s meadow jumping mouse) and designated wildlife overpasses for elk and also f or mule deer. The crossing structures may be combined with human co-use to connect the trails on the refuge with the trail system in the surrounding areas.
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    Electrified Barriers Installed on Top of Wildlife Guards to Help Keep Large Wild Mammals Out of a Fenced Road Corridor
    (Western Transportation Institute, Montana State University, 2023-12) Huijser, M.P.; Getty, S.C.
    Most wildlife mitigation measures along highways are aimed at improving human safety, reducing direct wildlife mortality, and providing safe crossing opportunities for wildlife. Fences in combination with wildlife crossing structures are the most effective combination of mitigation measures to achieve these objectives. For fences to reliably reduce collisions with large wild mammals by 80% or more, at least 5 kilometers (3 miles) of road length needs to be fenced, including a buffer zone that extends well beyond the known hotspots for wildlife-vehicle collisions. Collisions that still occur within the fenced road sections tend to be concentrated near the fence-ends. In addition, gaps in fences, including at access roads, can result in concentrations of collisions inside fenced road sections. Gates are commonly used at gaps in the fence at low traffic volume access roads, but they are often left open allowing wildlife to access the road corridor. While cattle guards or wildlife guards can be effective for some ungulate species, double wide cattle or wildlife guards consisting of round bars or bridge grate material, situated above a pit, are generally recommended for ungulates. However, such guards are not a substantial barrier for species with paws, including many carnivore species. Electrified mats or electrified guards can be a barrier for both ungulates and species with paws, but to prevent animals from jumping across the mat, they need to be 4.6-6.6 m (15-22 ft)) wide. For this project, a combination of wildlife guards and electrified barriers on top of these wildlife guards was evaluated. Both electrified mats that were tested (Crosstek and BS Fabrications) on top of existing wildlife guards resulted in a near absolute barrier for both ungulates and species with paws (97.9% barrier for the 2 deer species combined, 100% barrier for coyotes and black bears); an improvement to a wildlife guard only without an electrified mat (89.3% for the 2 deer species combined, 54.5% barrier for coyotes and 45.5% barrier for black bears). Based on the images, there is evidence that a shock is delivered to the animals that touch the electrified mats and that most of the animals respond by returning to the habitat side of the barrier. Specifically for bears, if it was not for the electrified barriers, likely at least 3 black bears and 1 grizzly bear would have crossed into the fenced road corridor where they would have been exposed to vehicles.
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    Supporting Employment Transportation in Southern Georgia
    (Western Transportation Institute, 2023-10) Clouser, Karalyn; Villwock-Witte, Natalie; Kissel, Carrie; Allphin, Bret
    The Southern Georgia Regional Commission (SGRC) is a regional planning agency that conducts economic development, regional transportation and environmental planning, local government services, aging programs, workforce development, geographic information systems (GIS), and other services for an eighteen-county region. The region includes Atkinson, Bacon, Ben Hill, Berrien, Brantley, Brooks, Charlton, Clinch, Coffee, Cook, Echols, Irwin, Lanier, Lowndes, Pierce, Tift, Turner, and Ware Counties. Within its rural regional transportation program, SGRC develops rural transit development plans (TDPs) under contract to the Georgia Department of Transportation. SGRC also administers coordinated human services transportation for clients of agencies within Georgia’s Department of Human Services. In the summer of 2021, SGRC began to operate rural public transit services on a regional basis called SGRC Regional Transit, providing a mobility option for 15 of the 18 counties in the region. One of the region’s goals in establishing region-wide rural public transit is to address economic development, including providing mobility to existing and potential employment sites. The region’s 2020 update to the Comprehensive Economic Development Strategy (CEDS) notes: “While some growth has been experienced within the region, persistent poverty, underemployment, and unemployment continue to plague the area.” Several goals and strategies in the CEDS relate to these issues of addressing poverty and employment. These include encouraging the establishment of transportation systems and facilities that support residents and visitors to broaden mobility options. In addition, some employers have already begun transportation services at their own expense. Others, including food processing business, have expressed to area workforce development and economic development professionals that they could create additional jobs if they had access to additional workers.
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    In Search of Simultaneous Benefits of Infrastructure Provisions on Freight & Bicycle Movements
    (Western Transportation Institute, 2023-10) Villwock-Witte, Natalie; Clouser, Karalyn; Kack, David
    The United States has three million miles of rural roadways (U.S. Department of Transportation, Federal Highway Administration, 2000). Some bicyclists enjoy recreating on low-volume rural roadways because they are looking for long rides to physically challenge themselves. Some rural Americans commute to work by bicycle or travel by bike for other trips (e.g., to the grocery store), whether they are driven by environmental motivators (they do not want to further pollute the environment) or practical purposes (they have limited or no vehicles in their households but still need to make trips). Regardless of the reason, bicyclists can be found on rural roadways. While many riders may self-select onto lower-volume roadways and roadways where there are fewer large vehicles, the limited redundancy of some rural roadway networks may force bicyclists to travel on roadways with higher traffic volumes, with higher posted speed limits, and with large vehicles. With extensive miles in the rural context, the question then becomes: can providing additional pavement in the form of wide shoulders benefit both motorists, particularly those in large vehicles carrying freight, and bicyclists on roadways used by both, or should a separated facility, like a cycle highway, be considered instead? Thus, the purpose of this project is to consider whether wider road shoulders could benefit both freight and bicyclists traveling along rural roadways. Through a literature review focused on the crash experience of bicyclists, the impact of the road design on a bicyclist’s crash experience, the impact of the vehicle type and vehicle technology on a bicyclist’s crash experience, and policies impacting how and where a bicyclist may travel, recommendations and conclusions are made regarding if benefits can be had by both bicyclists and freight (a.k.a., large vehicles) within a corridor.
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    Public Willingness to Raise Transportation Revenues, Priorities for Transportation Spending, and Preferences for Types of Transportation Revenues: Evidence from Montana’s Billings and Missoula Small Urban Areas
    (Western Transportation Institute, 2023-07) Hamre, Andrea; Fisher, Jonathan; Kack, David
    This project analyzed public willingness to raise transportation revenues, public priorities for transportation spending, and public preferences for transportation revenue types using recent household travel surveys for the small urban areas of Billings and Missoula. The share of the public willing to pay more taxes or fees for transportation improvements was 44% in Billings and 36% in Missoula (including neutral or undecided responses). This level of public support for increased transportation revenues is perhaps higher than generally perceived by leaders reluctant to publicly support a gas tax increase. Our results regarding transportation spending priorities are consistent with the prioritization of preserving existing transportation assets. Maintenance and repair of existing infrastructure received the most support of transportation spending options in both the Billings and Missoula survey samples. Our results regarding the preferred type of transportation revenue mechanism (available only for Missoula) suggested that a plurality of the sample (35% including neutral or undecided responses) preferred a $0.02 per gallon increase in fuel taxes to other options (such as an increase in sales or property taxes). Together, our results suggest a public willingness to more adequately fund transportation investments, a preference for spending on existing transportation assets, and a preference for more direct road user charges over less direct alternatives.
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    Transportation Planning and Public Health: To What Extent is Health Considered in Rural Local Transportation Plans?
    (Western Transportation Institute, 2023-05) MacFarlane, Jennifer; Kack, David
    Transportation systems can impact both physical and mental health, but the effects of transportation planning decisions on health, beyond safety and air pollution, are often overlooked or undervalued (Litman, 2013). Although not the only factor contributing to health disparities, transportation systems serve as a modifiable variable contributing to health behaviors and outcomes (Nieuwenhuijsen & Khreis, 2019). Following a similar approach to Singleton and Clifton (2017), a review of transportation planning documents from the ten most populous counties within the state of Montana was conducted to analyze the extent that health was considered. A directed and summative approach was used to identify and code health-related guidance statements, performance measures, and reference data in the domains of general health, safety, air quality, physical activity, accessibility, mental health, and equity. Although all transportation plans contained health-related guidance statements and reference data, only those transportation plans from counties containing a metropolitan planning organization (MPO) included health-related performance measures. The inclusion of health-related guidance statements and reference data is evidence that local Montana communities are interested in the impacts of transportation planning on health behaviors and outcomes. Without the federal requirements that MPOs must follow, rural governments are not utilizing health-related performance measures to fully understand performance of the local transportation system related to their community’s public health priorities. The existing performance management structure required of States and MPOs could serve as a guide for further integrating health-related performance measures into small urban and rural transportation planning and can assist local decision makers in analyzing progress toward community priorities (Singleton & Clifton, 2017).
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    Bees and Butterflies in Roadside Habitats: Identifying Patterns, Protecting Monarchs, and Informing Management
    (ITD Reseach Program, 2023-07) Meinzen, Thomas C.; Debinski, Diane M.; Burkle, Laura A.; Ament, Robert J.
    Pollinating insects provide vital ecosystem services and are facing global declines and habitat loss . Roadsides are increasingly regarded as important potential areas f or enhancing pollinator habitat. Understanding which roadsides best support pollinators — and why — is essential to helping locate and prioritize pollinator conservation efforts across roadside networks. To support this effort, we assessed butterfly, bee, and flowering plant species richness and abundance on a set of 63 stratified randomized roadside transects in State-managed rights-of-way in SE Idaho. Our research evaluated pollinator diversity as a function of highway class (interstate, U.S., and state highways), remotely sensed NDVI values (a measure of vegetation greenness), and floral resources. We found that smaller highways and lower (less green) maximum NDVI values were associated with significantly more bee species and total bees. Roadsides bordering sagebrush habitats typically had low NDVI values and higher bee and butterfly species richness, potentially contributing to this observed pattern. Butterfly richness increased in association with higher floral abundance in roadsides. Additionally, we identified and mapped 1,363 roadside patches of milkweed (Asclepias speciosa), larval host plant for the imperiled monarch butterfly (Danaus plexippus), in a survey of over 900 miles of southern Idaho highways. Based on these results and a literature review, we recommend management strategies to promote the health of pollinator populations in Idaho’s rights-of-way and provide data to help ITD prioritize areas for pollinator-friendly management practices and habitat restoration within their highway system.
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    Statewide GNSS-RTN Systems: Current Practices
    (Scientific Research Publishing, Inc., 2023-01) Raza, Sajid; Al-Kaisy, Ahmed
    The applications of geospatial technologies and positioning data embrace every sphere of modern-day science and industry. With technological advancement, the demands for highly accurate positioning services in real-time led to the development of the Global Navigation Satellite System—Real-Time Network (GNSS-RTN). While there is numerous published information on the technical aspects of the GNSS-RTN technology, information on the best practices or guidelines in building, operating, and managing the GNSS-RTN networks is lacking in practice. To better understand the current practice in establishing and operating the GNSS-RTN systems, an online questionnaire survey was sent to the GNSS-RTN system owners/operators across the U.S. Additionally, a thorough review of available literature on business models and interviews with representatives of two major manufacturers/vendors of GNSS-RTN products and services were conducted. Study results revealed a great deal of inconsistency in current practices among states in the way the GNSS-RTN systems are built, operated, and managed. Aspects of the diversity in state practices involved the business models for the GNSS-RTN systems besides the technical attributes of the network and system products. The information gathered in this study is important in helping state agencies make informed decisions as they build, expand or manage their own GNSS-RTN systems.
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    Transportation Research Record: Journal of the Transportation Research Board
    (SAGE Publications, 2023-02) Raza, Sajid; Al-Kaisy, Ahmed; Washburn, Scott; Barrios, Jorge; Tsui Moreno, Ana; Schroeder, Bastian
    Understanding the influence of intersections on operating conditions along connecting roadway segments is important for the analysis of highway facilities and corridors. This study aims at assessing the influence area at signalized and stop-control intersections along rural corridors. The study used speed as a performance measure in examining the spatial extent of operational effects at intersections. High-fidelity connected vehicle (CV) trajectory data, collected at 11 different sites in Florida, was used in this study. The CV trajectory data consists of individual waypoints that included timestamps and location coordinates along with other attributes. Drivers’ speed profiles while driving through the intersection were established and analyzed to determine the length of upstream and downstream influence areas. Quantile regression models were developed to estimate the 50th, 70th, and 85th percentiles of upstream and downstream influence areas separately for signalized and stop-control intersections. Study results indicate that the upstream influence area is longer for a signalized intersection than for a stop-control intersection for comparable segment running speeds. Further, the downstream influence area is significantly longer than the upstream influence area at signalized intersections, and this was consistent at all study sites. Traffic flow level did not have a significant effect on the upstream or downstream influence area; however, midblock running speed, percent heavy vehicles, and facility type (multilane versus two-lane) were found to significantly affect the upstream and downstream influence areas at signalized intersections.
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    Statewide GNSS-RTN Systems: Current Practices
    (Scientific Research Publishing, Inc., 2023-01) Raza, Sajid; Al-Kaisy, Ahmed
    The applications of geospatial technologies and positioning data embrace every sphere of modern-day science and industry. With technological advancement, the demands for highly accurate positioning services in real-time led to the development of the Global Navigation Satellite System—Real-Time Network (GNSS-RTN). While there is numerous published information on the technical aspects of the GNSS-RTN technology, information on the best practices or guidelines in building, operating, and managing the GNSS-RTN networks is lacking in practice. To better understand the current practice in establishing and operating the GNSS-RTN systems, an online questionnaire survey was sent to the GNSS-RTN system owners/operators across the U.S. Additionally, a thorough review of available literature on business models and interviews with representatives of two major manufacturers/vendors of GNSS-RTN products and services were conducted. Study results revealed a great deal of inconsistency in current practices among states in the way the GNSS-RTN systems are built, operated, and managed. Aspects of the diversity in state practices involved the business models for the GNSS-RTN systems besides the technical attributes of the network and system products. The information gathered in this study is important in helping state agencies make informed decisions as they build, expand or manage their own GNSS-RTN systems.
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    Influence Area at Signalized and Stop-Control Intersections: Operational Analysis
    (SAGE Publications, 2023-02) Raza, Sajid; Al-Kaisy, Ahmed; Washburn, Scott; Barrios, Jorge; Moreno, Ana Tsui; Schroeder, Bastian
    Understanding the influence of intersections on operating conditions along connecting roadway segments is important for the analysis of highway facilities and corridors. This study aims at assessing the influence area at signalized and stop-control intersections along rural corridors. The study used speed as a performance measure in examining the spatial extent of operational effects at intersections. High-fidelity connected vehicle (CV) trajectory data, collected at 11 different sites in Florida, was used in this study. The CV trajectory data consists of individual waypoints that included timestamps and location coordinates along with other attributes. Drivers’ speed profiles while driving through the intersection were established and analyzed to determine the length of upstream and downstream influence areas. Quantile regression models were developed to estimate the 50th, 70th, and 85th percentiles of upstream and downstream influence areas separately for signalized and stop-control intersections. Study results indicate that the upstream influence area is longer for a signalized intersection than for a stop-control intersection for comparable segment running speeds. Further, the downstream influence area is significantly longer than the upstream influence area at signalized intersections, and this was consistent at all study sites. Traffic flow level did not have a significant effect on the upstream or downstream influence area; however, midblock running speed, percent heavy vehicles, and facility type (multilane versus two-lane) were found to significantly affect the upstream and downstream influence areas at signalized intersections.
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    Animal Vehicle Collision Reduction and Habitat Connectivity Cost Effective Solutions - Final Report
    (Nevada Department of Transportation, 2022-07) Ament, Rob; Huijser, Marcel; May, Dana
    Wildlife-vehicle collisions (WVCs) are a significant component of overall crashes in the US and Canada. Roads and their traffic also create partial or total barriers to the movement of wildlife, both large and small. There are several well-studied proven mitigation measures that significantly reduce WVCs, provide for safe animal passage across roads, and maintain habitat connectivity. Highly effective measures, such as overpasses and underpasses with fencing can reduce large animal WVCs by over 80% – 100% on average; yet these structures can be costly and there is room for improvement in their design, the use of new materials, adding elements that improve their use by smaller animal species, such as reptiles and amphibians and improving their cost effectiveness. This Transportation Pooled Fund Study, TPF-5(358) (TPF Study), allowed researchers to evaluate the latest information on the effectiveness of 24 different highway mitigation measures designed to decrease collisions with large wildlife, large feral and domestic animals. Also reviewed were these same measures’ ability to protect small mammals, reptiles, and amphibians from collisions. The TPF Study also explored the effectiveness of the 24 measures ability to maintain or enhance habitat connectivity. It conducted 11 different research projects that variously explored a) the costs and benefits of animal-vehicle collisions and the mitigation measures that seek to reduce them, b) the ecological effectiveness of various mitigation measures, and 3) new designs for crossing structures for a variety of species. The project developed a manual of best practices and concluded with a final report.
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    Best Practices Manual to Reduce Animal-Vehicle Collisions and Provide Habitat Connectivity for Wildlife
    (Nevada Department of Transportation, 2022-09) Huijser, M.P.; Fairbank, E.R.; Paul, K.S.
    The goal for this manual is to provide practical information for the implementation of mitigation measures that aim to: 1. Improve human safety through reducing collisions with large animals, including large wild mammal species, select free roaming large feral species, and select free roaming large livestock species, and 2. Improve or maintain habitat connectivity for terrestrial wildlife species and selected feral species through safe crossing opportunities. This manual does not include all possible measures that can or may reduce animal-vehicle collisions and maintain or improve habitat connectivity for wildlife. The measures included in this manual are: Barriers (fences) in combination with crossing structures (for large wild mammals and for small wild animal species), roadside animal detection system, Barriers (fences), Barriers (fences) in combination with crossing structures (for free roaming livestock), and culling, relocation, anti-fertility treatment, roadside animal detection systems, barriers (fences), and barriers (fences) in combination with crossing structures (for large feral mammal species such as feral horses and burros).
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    Long-term responses of an ecological community to highway mitigation measures
    (Nevada Department of Transportation, 2022-07) Ford, Adam T.; Huijser, Marcel; Clevenger, Anthony P.
    In road mitigation systems characterized by multiple wildlife crossing structures (CS) and multiple-focal species, these species-specific design criteria are important to meeting management goals. CS types and locations are fixed in place and cannot be manipulated experimentally; long term studies may offer the best chance to inform evidence-based designs for new CS projects in the future. Long-term data from Banff National Park are uniquely posed to answer these critical questions. More recently, highway mitigation along US93 in Montana provides an additional case study with which to understand the responses of large animals to different CS designs. The purpose of this study is to identify factors affecting movement of large mammals through CS using data sets from both mitigation projects. Year-round monitoring of CS use was used in an analytical framework to address questions regarding species-specific and community level use of CS; design and habitat factors that best explain species-specific variation; and whether importance of design parameters changes over time. Over the 17 years of the Banff study, and the six years of the Montana study, CS facilitated over 200,000 crossing events at 55 locations. There were significant changes in annual crossing events over time. Variables associated with CS passage rates were species specific, but aligned with a few clusters of preference. With the exception of coyotes, all large carnivore species preferred open span bridges or overpasses to other CS types. In Montana, fencing was positively associated with passage rates for black bears and cougars. We found that wider CS tend to be preferred by most species, irrespective of their location. We also found that wider CS tend to have shorter ‘adaptation’ curves than narrower ones for grizzly bears, coyotes, cougars, and moose. Depending on the heterogeneity of the landscape near the highway, more CS may not create more crossing opportunities if local habitat conditions do not favor animals’ access to the road. At the scale of ecological communities, the flows of mass and energy are likely enough to alter the distribution of ecological processes in the Banff and Montana ecosystems. Our results highlight the value of long-term monitoring for assessing the effectiveness of mitigation measures. Our work confirms the species-specific nature of measure CS performance, leading to our primary recommendation that a diversity of CS designs be considered an essential part of a well-designed mitigation system for the large mammals of western North America. Short-term monitoring efforts may fail to accurately portray the ecological benefits of mitigation for populations and ecological communities. Our results will help to inform design and aid in the establishment of robust, long-term performance measures.
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    The effectiveness of electrified barriers to keep large mammals out of fenced road corridors
    (Nevada Department of Transportation, 2022-09) Huijser, M.P.; Getty, S.C.
    For this project the researchers investigated the effectiveness of different types of electrified barriers for varying traffic volume and traffic speed. Some barriers were investigated for carnivores only, whereas others were evaluated for both ungulates and carnivores. Finally, we combined the data from our field studies with those reported in the literature and conducted a meta-analysis to investigate the effectiveness of different types and dimensions of barriers for both ungulates and carnivores. In general, electrified barriers can be a substantial barrier to species with paws, including black bears. However, careful maintenance and monitoring is required for these measures to succeed.
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    Modified jump-outs for white-tailed deer and mule deer
    (Nevada Department of Transportation, 2022-09) Huijser, Marcel; Getty, S.C.
    The height of the jump-outs should be low enough for the target species to readily jump down to the safe side, or the habitat side, of the fence. At the same time, the jump-outs should be high enough to discourage animals that are on the habitat side of the fence from jumping up into the fenced road corridor. Previous research along US Hwy 93 North in Montana showed that only about 32% of the mule deer and about 7% of the white-tailed deer that appeared on top of the jump-outs, jumped down to safety. For this project, 10 of the jump-outs along US Hwy 93 North were lowered in height and provided with a bar on top. The height of the bars (made from rebar) and their setback from the vertical face of the jump-outs was adjustable and the researchers applied 4 different treatments: 2 different heights (18 and 15 inches) and 3 different setbacks (4, 12, and 15 inches). The overall effectiveness of the lowered jump-outs in allowing white-tailed deer to jump down, regardless of the height and setback of the bar, was only just above 5% (no improvement). For mule deer the effectiveness of the lowered jump-outs in allowing them to jump down, regardless of the height and setback of the bar, was about 64% (this was double the effectiveness of non-modified jump-outs).
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    Implementing wildlife fences along highways at the appropriate spatial scale: A case study of reducing road mortality of Florida Key deer
    (Pensoft Publishers, 2022-03) Huijser, Marcel P.; Begley, James S.
    Florida Key deer mortality data (1966–2017) showed that about 75% of all reported deer mortalities were related to collisions with vehicles. In 2001–2002, the eastern section of US Hwy 1 on Big Pine Key (Florida, USA) was mitigated with a wildlife fence, 2 underpasses, and 4 deer guards. After mitigation, the number of reported Key deer road mortalities reduced substantially in the mitigated section, but this was negated by an increase in collisions along the unmitigated section of US Hwy 1 on Big Pine Key, both in absolute numbers and expressed as a percentage of the total deer population size. The data also showed that the increase in Key deer collisions along the unmitigated highway section on the island could not be explained through an increase in Key deer population size, or by a potential increase in traffic volume. The overall Key deer road mortality along US Hwy 1 was not reduced but was moved from the mitigated section to the nearby unmitigated section. Thus, there was no net benefit of the fence in reducing collisions. After mitigation, a significant hotspot of Key deer-vehicle collisions appeared at the western fence-end, and additional hotspots occurred further west along the unmitigated highway. Exploratory spatial analyses led us to reject the unmitigated highway section on Big Pine Key as a suitable control for a Before-After-Control-Impact (BACI) analysis into the effectiveness of the mitigation measures in reducing deer-vehicle collisions. Instead, we selected highway sections west and east of Big Pine Key as a control. The BACI analysis showed that the wildlife fence and associated mitigation measures were highly effective (95%) in reducing deer-vehicle collisions along the mitigated highway section. Nonetheless, in order to reduce the overall number of deer-vehicle collisions along US Hwy 1, the entire highway section on Big Pine Key would need to be mitigated. However, further mitigation is complicated because of the many buildings and access roads for businesses and residences. This case study illustrates that while fences and associated measures can be very effective in reducing collisions, wildlife fences that are too short may result in an increase in collisions in nearby unmitigated road sections, especially near fence-ends. Therefore it is important to carefully consider the appropriate spatial scale over which highway mitigation measures are implemented and evaluated.
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