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The National Academies

NCHRP 25-25/Task 117 [Anticipated]

Valuing Wildlife Crossing Enhancements for Mitigation Credits
[ NCHRP 25-25 (Research for the AASHTO Standing Committee on the Environment) ]

  Project Data
Funds: $115,000
Staff Responsibility: Ann M. Hartell
Comments: In development
Fiscal Year: 2018


Wildlife crossings and enhancements are often integrated into transportation projects and are becoming more common within long-term mitigation planning for many state DOTs and transportation agencies. Yet, there are unknowns regarding methods to calculate the values of connected habitats, improvements to wildlife permeability, and mitigation crediting with certain types of wildlife enhancements on highways. Metrics that define improvements to individual species, their habitats or populations are important tools for streamlining state DOT transportation project environmental permitting and delivery, as they can inform requirements for mitigation within Federal Endangered Species Act (FESA) consultation, as well as other permits.  When in-place, consistent valuing and crediting methodologies, or available advance mitigation credits, may reduce transportation project administrative costs and complexity.  Further, wildlife crossing structures—such as wildlife overpasses, underpasses, bridges, and culverts—can be located completely within a state DOTs right-of-way, where state DOTs have control, and schedules for performing mitigation or constructing advance mitigation within a state DOT’s right-of-way may be more predictable than off-system. Such approaches are consistent with the Integrated Ecological Framework (IEF) that directs transportation agencies to “develop a consistent strategy and metrics to measure ecological impacts, restoration benefits, and long-term performance.” 

This Task would collect information and present the body of knowledge regarding habitat connectivity valuing methods, metrics and criteria for credit development, and project crediting mechanisms for wildlife connectivity improvements. The effort will provide an initial step towards developing valuing and crediting methods for constructed wildlife crossings that could be used by state DOTs in the process of meeting their environmental permit requirements for mitigation performing FESA consultation.

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