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Evaluation of the Use and Effectiveness of Wildlife Crossings (2008)

Chapter: Chapter 1 - Introduction and Research Approach

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Suggested Citation:"Chapter 1 - Introduction and Research Approach." National Academies of Sciences, Engineering, and Medicine. 2008. Evaluation of the Use and Effectiveness of Wildlife Crossings. Washington, DC: The National Academies Press. doi: 10.17226/14166.
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Suggested Citation:"Chapter 1 - Introduction and Research Approach." National Academies of Sciences, Engineering, and Medicine. 2008. Evaluation of the Use and Effectiveness of Wildlife Crossings. Washington, DC: The National Academies Press. doi: 10.17226/14166.
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Page 11
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Suggested Citation:"Chapter 1 - Introduction and Research Approach." National Academies of Sciences, Engineering, and Medicine. 2008. Evaluation of the Use and Effectiveness of Wildlife Crossings. Washington, DC: The National Academies Press. doi: 10.17226/14166.
×
Page 12
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Suggested Citation:"Chapter 1 - Introduction and Research Approach." National Academies of Sciences, Engineering, and Medicine. 2008. Evaluation of the Use and Effectiveness of Wildlife Crossings. Washington, DC: The National Academies Press. doi: 10.17226/14166.
×
Page 13
Page 14
Suggested Citation:"Chapter 1 - Introduction and Research Approach." National Academies of Sciences, Engineering, and Medicine. 2008. Evaluation of the Use and Effectiveness of Wildlife Crossings. Washington, DC: The National Academies Press. doi: 10.17226/14166.
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Page 14

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10 Introduction “For a generation, North Americans have been in simul- taneous pursuit of twin goals that are inherently in conflict. On the one hand, they seek to harvest the manifold benefits of an expanding road system, including a strong economy, more jobs, and better access to schools, friends, family, recreation, and cheaper land on which to build ever larger homes. On the other, they have growing concerns about threats to the natural environment, including air and water quality, wildlife habitat, loss of species, and expanding urban encroachment on rural landscapes. . . . Not surpris- ingly, these conflicting demands clash wherever transporta- tion decisions are made, whether at the federal, state, or local levels. . . . ad hoc environmental analysis has left many gaps in our understanding of effective mitigation for individual road projects and is unlikely to ever lead to ef- fective mitigation of the macro effects of a growing system of roads.” Thomas B. Deen, Executive Director (retired) Transportation Research Board, National Academy of Sciences Member, National Academy of Engineering Foreword to Road Ecology: Science and Solutions98 “In the past century, dramatic changes have been made in the U.S. road system to accommodate an evolving set of needs, including personal travel, economic development, and military transport. As the struggle to accommodate larger volumes of traffic continues, the road system is in- creasing in width and, at a slower pace, overall length. As the road system changes, so does the relationship between roads and the environment. With the increase in roads, more resources are going toward road construction and manage- ment. More is also understood about the impact of roads on the environment. To address these matters, a better under- standing of road ecology and better methods of integrating that understanding into all aspects of road development are needed.” Dr. Lance Gunderson (chair) Committee on Ecological Impacts of Road Density, National Research Council Preface to Assessing and Managing the Ecological Impacts of Paved Roads181 “My visions for the future are as follows. Road design in future will commence with selection of routes with least eco- logical impacts. Wildlife bridges and tunnels will be located and built to minimum standards. There will be ecological restoration of roadside verges. “For every square metre of road there will be at least the equivalent of land set aside for nature. Roads will become linear nature reserves with hedgerows of native species and a wide swathe on either side as a nature reserve. These linear nature reserves will be habitats for rare and endangered species. Roadside verges will be enjoyed by all and traffic will slow to allow travelers to enjoy roadside nature.” Dr. Ian F. Spellerberg, Professor of Nature Conservation Lincoln University, Aotearoa, New Zealand Chapter 8 of Ecological Effects of Roads217 These remarks suggest that transportation services and environmental concerns need to be effectively linked in a landscape context-sensitive planning, construction, and monitoring process. They also provide an optimistic vision of the future, given the concerted efforts and purposeful ac- tivity towards linking transportation services and ecological services that have increased dramatically during the past few years. For decades, environmental mitigation was not con- sidered an integral part of road construction and piecemeal and haphazard mitigation approaches did not provide high- way planners and engineers with useful data that could be generalized to different situations. However, following the completion of the interstate highway system, a new post- C H A P T E R 1 Introduction and Research Approach

11 interstate era began with the passage of the Intermodal Sur- face Transportation Efficiency Act of 1991 (ISTEA), which effectively shifted responsibilities and funding from national priorities to local needs and greater state and local govern- ment authority, while at the same time placing greater em- phasis on environmental mitigation and enhancement.98 In 1998, the Transportation Equity Act for the 21st Century (TEA-21) retained this basic emphasis. The 2005 Safe, Ac- countable, Flexible, Efficient Transportation Equity Act: a Legacy for Users (SAFETEA-LU) continued this move to- ward environmental mitigation and gave even greater im- portance to facilitating both terrestrial and aquatic passage of wildlife, while also instructing that when metropolitan plans and statewide plans for transportation are developed, they must include “a discussion of potential environmental mitigation activities and potential areas to carry out these activities” (SAFETEA-LU, Public Law 109-59, Title VI, Sec.6001 Transportation Planning Transportation Bill [Con- servation provisions of interest in SAFETEA-LU found at Defenders of Wildlife site: www.defenders.org/habitat/ highways/safetea/; to read the text of the bill, see frwebgate. access.gpo.gov/cgi-bin/getdoc.cgi?dbname=109_cong_public_ laws&docid=f:publ059.109]). In Canada, Transport Canada published Road Safety Vision 2010, which calls for decreases of 30% in the num- ber of motorists killed or seriously injured. Over the last decade, legislation and policy including the National Parks Act and the Parks Canada Policy document have placed the highest priority on the protection of ecological integrity, and include mitigation for wildlife on upgrades to high- ways within National Parks. Additionally, the recent Species at Risk Act in Canada has made planning and mit- igation for WVCs even more critical a concern for highway planners and engineers. Given the mandate of these major legislative acts, highway planners and engineers across the United States and Canada have begun to integrate mitiga- tion as part of their mandate. For example, British Colum- bia has developed a 10-year strategic plan to reduce wildlife collisions by 50%. However, even with forward-looking ac- tions and excellent reports such as Assessing and Managing the Ecological Impacts of Paved Roads181 and a large litera- ture on ecological “road effects,” there remains an obvious lack of synthesis documents to inform and help guide high- way planners and engineers with environmental mitigation and enhancement. Linking transportation and ecological services effectively requires an integrated understanding of the science so that mitigation practices may be based on data. Historically, linking transportation and ecological services may have seemed inherently in conflict but they need not be so. One can envision roads as having a physical and a virtual footprint. The physical footprint is easy to see and includes the actual dimensions of the road (length and width) as well as the dimensions of associated structures, e.g., the right-of- way. The virtual footprint is much larger and includes the area where the indirect effects of roads are manifested. The roaded landscape has both direct and indirect effects on wildlife species, community biodiversity, and ecosystem health and integrity. The most prevalent direct effect is road- kill. Indirect effects include habitat loss, reduced habitat qual- ity, fragmentation, barrier effects, and loss of connectivity resulting in restricted or changed animal movement patterns. The virtual footprint, therefore, can be understood only when put into a landscape context-sensitive perspective. Here the Cinderella Principle needs to be applied, i.e., establishing mit- igation that effectively “shrinks” the virtual footprint to more closely resemble the physical footprint.26 For surface trans- portation, applying the Cinderella Principle means that high- way planners and engineers need to continue to incorporate mitigation measures that restore ecological integrity and landscape connectivity, while at the same time ensuring safe state-of-the-art transportation services in a cost-effective manner. This job is not inherently difficult, but it does re- quire purposeful activity guided by informed, synthetic analyses that reflect true benefits and costs. The research team defined transportation services to mean, among other things, safe, efficient, reliable roads; inexpensive transportation; properly constructed intersections: safe and quiet road sur- faces; good visibility; safe bridges; and good signage. By ecosystem services, the research team means clean water, clean air, uncontaminated soil, natural intact landscape processes, recreational opportunities, abundant wildlife, nor- mal noise levels, and a connected landscape that leads to restoration and maintenance of life-sustaining ecological processes. Currently across North America, a mismatch exists. Ecosys- tem services have been compromised by road construction. The virtual road footprint is too large. The research team suggests that the overarching principle that needs to guide fu- ture road construction, renovation, and maintenance also needs to link both transportation and ecological services. That is partly accomplished by reestablishing multiple connections across the landscape. The mechanism by which connectivity is established involves moving from roaded landscapes that are nearly impermeable to landscapes that are semi-permeable and finally, to landscapes that are fully permeable; when accomplished, the landscape is connected, and ecological ser- vices are restored. Nearly normal hydrologic flow, facilitated animal movement, reconnection of isolated populations, and gene flow are made possible. In other words, the Cinderella Principle of shrinking the virtual footprint has been applied effectively, restoring landscape permeability. Ecological objectives have been met coincident with a continually effec- tive roadway network.

12 The concept and practical application of permeability might best be understood by an example. Imagine a couple who live in a small town or suburb. They work close to their home and shop in the neighborhood. They have walking access to a gro- cery store, a church, a pharmacy, a movie theater, a medical clinic—in short, all of the amenities they need for a happy and comfortable life. Then suppose that a major road that runs through the suburb is enhanced and made into a four-lane di- vided interstate highway, with its accompanying fences and barriers, to accommodate the increased traffic and to provide the requisite and expected transportation services. Because of the location of the road, it now separates the imaginary couple from their work and the amenities that they depended on and could access easily before. The couple, who always walked to access these amenities and resources, is now blocked by the highway. The highway does, however, provide connectivity in the form of crosswalks spaced approximately six to eight blocks apart. The couple has a choice. They can either use their car and bear with the heavy traffic, or walk many more blocks to access the crosswalks that would allow them to cross the road. It is unsafe for them to cross the highway in any place other than the crosswalks provided. Their cohesive neighborhood is still connected, but much less permeable. This is the critical difference between connectivity and permeability. Regardless of the choice they make, the couple now find accessing the resources they need for everyday life to be much more difficult and to entail much longer distances and a greater time commitment. Although fanciful, this everyday urban situation is analogous to what happens to ecosystem resources for wildlife when high- ways are built across natural landscapes. Connectivity can be maintained by crossings, but the placement, type, and configuration of the crossing will determine whether permeability is impacted. Think of cross- ings as a funnel that guides animals under or over roads. Then imagine a context-sensitive road design that incorporates dif- ferent types and designs of crossings in appropriate locations. The result can be thought of as a “sieve” that facilitates ani- mal movement, rather than a “funnel.” Connectivity evolves to permeability. Restoring connectivity is a land-based con- cept and easy to understand. However, as can be seen by the example given previously, it is not necessarily equivalent with the idea of landscape permeability, which is an animal- centered concept. The difference between the two concepts involves the idea of scale-sensitive (allometric), animal-based movement. Perme- ability implies the ability of the animal to move across its home range or territory (its ecological neighborhood) in a relatively unhindered manner, i.e., movement ease can be indexed by es- sentially a straight-line distance to resources. In scientific terms, the fractal measure of the pathway is non-tortuous and is of low dimension. Anything that hinders movement or increases dis- tance moves the landscape in the direction of impermeability. Scale-sensitivity considerations enter the picture because dif- ferent animals have different movement capabilities and re- spond to the same landscape in very different ways. A mouse does not use or move across its home range in the same way a moose does. Hence, an assessment of the local animal commu- nity that exists in the landscape that the road crosses is essential and will suggest different crossing types, configurations, and locations in order to achieve permeability in roaded land- scapes. Understanding animal behavior is critical in achieving permeability. Providing guidance on the use and effectiveness of wildlife crossings to mitigate habitat fragmentation and reduce the number of WVCs involves thinking in a large-scale, context- sensitive framework that is based on sound ecological princi- ples. Connectivity is intimately linked to permeability. Permeability is the goal of smart roads and intelligent mitiga- tion. The goal for this research project is based on this prem- ise: understanding and establishing landscape permeability guidelines that lead to effective landscape connectivity and the restoration of ecosystem integrity—while continuing to provide efficient and effective transportation infrastructure in a cost-effective economic manner. Research conducted for this project was undertaken with the goal to evaluate how the selection, configuration, and location of crossing facilities can help restore landscape permeability as well as provide for improved motorist safety. According to Evink,79 motorist safety and the problems re- sulting from vehicular collisions with wildlife are important concerns. Wildlife–vehicle collision studies are used as an analytical guide to identify overall trends and problem areas because collisions with larger animals can result in substan- tial damage and personal injury. However, available datasets often do not include collisions with elk, moose, or caribou and seldom address collisions caused by “swerve to miss” responses by the driver, phenomena that will certainly in- crease the valuation of damage caused by WVCs. There are serious methodological problems associated with current WVC research. The research of relevance to safety concerns addressed in this document use relevant data and models to identify collision-prone locations and to evaluate the safety effectiveness of wildlife crossing measures. Research Approach The objectives of this project are to provide clearly written guidelines for: • The selection of crossing types, • Their configuration, • Their appropriate location, • Monitoring and evaluation of crossing effectiveness, and • Maintenance.

13 Figure 1. Vision for NCHRP Project 25-27. The guidelines take the form of this final report and a web- based interactive decision guide (www.wildlifeandroads.org). The project vision was to integrate safety and ecological approaches to the problem of WVCs and the loss of ecological permeability along roads. Identification of the gaps and pri- orities for both research and practice were used to develop a state-of-the-art analysis that influenced the approach to the research conducted for this project. Integration of two very different research efforts, safety and ecological, required a clear focus and overt action to accomplish. Here is why: The safety analyses and the ecological analyses use essentially the same basic data (i.e., carcass and animal collision data); however, different auxiliary data are needed depending on the focus of the modeling and analyses, either safety or ecological. For ex- ample, for the safety modeling and analyses, right-of-way data, commonly referred to as “geometrics,” are coupled with AVC data to provide the bases for the rigorous empirical Bayesian approach. The primary objective for this modeling and analyses was safety. For the environmental modeling, mapping, and analyses, off-road variables, coupled with either carcass or WVC data, provided the basis for the rigorous ap- proaches used, although some ROW variables were included. The primary objective for this modeling and analyses was aimed at landscape permeability and healthy animal popula- tions. In other words, the fundamental dataset (carcass data or animal collision data) was used with different variables for very different purposes. Both safety and ecological approaches are necessary to effectively select the type, number, and loca- tion of crossing facilities. When integrated, issues of both safety and landscape permeability are satisfied (Figure 1). The goal of this project was to develop and integrate these two fundamentally different research approaches and incorporate them effectively into the final interactive decision guide. Structure of the Report The project was divided into two phases. Phase 1 entailed an investigation of current relevant research and practices concerning wildlife crossings (Tasks 1 and 2) and an identifi- cation of significant gaps and priorities in both research and practice (Task 3). Phase 2 entailed five distinct research efforts to help bridge the knowledge gaps in research (Task 7) and de- velopment of a web-based decision guide (Task 8). This report documents the research team’s activities for the project. Chapter 2 includes results for Tasks 2 and 3 from Phase 1. Chapter 3 covers the research conducted in Phase 2 in five sec- tions. Section 3.1 discusses the application of reported WVC data typically available in state DOT databases and investigates how the application of two databases, reported WVCs and carcass removals, can lead to different roadway improvement decisions. Section 3.2 includes analyses of WVC data and explores the limiting effects of roadkill reporting data due to

14 spatial inaccuracy. Section 3.3 investigates various WVC hotspot identification (clustering) techniques that can be used in a variety of landscapes, taking into account different scales of application, from project-level to state-level analysis, and transportation management concerns (e.g., motorist safety, endangered species management). Section 3.4 investigates the influence highways may have on the relative abundance of small mammals and how far any observed effect might extend into adjacent habitats. Section 3.5 explores whether the relationship between dispersal distances and home range size of mammalian species can be used to develop scaling relationships to decide on the placement of wildlife crossings that will help restore landscape permeability across fragmented habitat networks. Each of these sections is organized into five subsections: (1) Introduction; (2) Research Approach: Methods and Data; (3) Findings and Results; (4) Interpretation, Appraisal, and Applications; and (5) Conclusions and Suggested Research. Section 3.6 explains the distinctions among three of these re- search methods: safety data analysis, accuracy modeling, and hotspot modeling. Chapter 4 provides a brief description of the web-based interactive decision guide (www.wildlifeandroads.org) and instructions on how to use the guide. The References and appendices, which provide material that supports the information in the chapters, are given at the end of the document.

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TRB’s National Cooperative Highway Research Program (NCHRP) Report 615: Evaluation of the Use and Effectiveness of Wildlife Crossings explores the development of an interactive, web-based decision guide protocol for the selection, configuration, and location of wildlife crossings. The decision tool as outlined in the report is available online.

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