Title 23HighwaysRelease 119-73

§172 Wildlife-vehicle collision reduction and habitat connectivity improvement

Title 23 › Chapter CHAPTER 1— - FEDERAL-AID HIGHWAYS › § 172

Last updated Apr 6, 2026|Official source

Summary

Requires the Secretary of Transportation to study how to cut collisions between cars and wildlife and how roads affect animal habitats. The study must update the 2008 reports, look at causes and effects of wildlife-vehicle collisions, and examine how roads and traffic hurt habitat connections for land and water species. It must find solutions and best practices. To do that, the Secretary must review research and data, survey Federal and State transportation practices, and talk with experts. The Secretary must send Congress a report within 18 months after the Surface Transportation Reauthorization Act of 2021 is enacted. The report must describe causes and impacts (including effects on species listed as threatened or endangered under the Endangered Species Act, species states call “greatest conservation need,” species in State wildlife plans, and medium and small terrestrial and aquatic species), include an economic analysis of costs and benefits (including effects on jobs, property values, and economic growth for society, nearby communities, and landowners), give recommendations and best practices, and offer guidance for voluntary joint statewide transportation and wildlife action plans for any State that wants to participate. The Secretary must also create in-person and online training courses within 3 years to reduce collisions and improve habitat connections, make them available to transportation and fish and wildlife professionals, and update them at least every 2 years. The Secretary, through the Federal Highway Administration, must make a standard, high-quality method to collect and report exact location data for wildlife collisions and carcasses on the National Highway System, keeping technology and cost in mind. That work must review existing systems (for example, FARS and other crash data systems), try to fix their limits, and include consultation with federal, Tribal, State, and local transportation and wildlife agencies, planning organizations, experts, and other stakeholders. A template for State use should be developed and promoted voluntarily. A report describing the method must go to Congress no later than the later of 18 months after enactment or 180 days after the method is finished. By 4 years after enactment the Secretary must report to Congress on how much the voluntary system is being used, whether it helped reduce collisions or improve connectivity and by how much, and any further recommendations. The Secretary must also give voluntary guidance to States on when a highway should be checked for fixes, using a threshold that looks at human safety risks from collisions, highway-related wildlife deaths and effects on listed and State-priority species and medium and small species, and the road’s barrier effect on animal movements.

Full Legal Text

Title 23, §172

Highways — Source: USLM XML via OLRC

(a)(1)The Secretary shall conduct a study (referred to in this subsection as the “study”) of the state, as of the date of the study, of the practice of methods to reduce collisions between motorists and wildlife (referred to in this section as “wildlife-vehicle collisions”).
(2)(A)The study shall—
(i)update and expand on, as appropriate—
(I)the report entitled “Wildlife Vehicle Collision Reduction Study: 2008 Report to Congress”; and
(II)the document entitled “Wildlife Vehicle Collision Reduction Study: Best Practices Manual” and dated October 2008; and
(ii)include—
(I)an assessment, as of the date of the study, of—
(aa)the causes of wildlife-vehicle collisions;
(bb)the impact of wildlife-vehicle collisions on motorists and wildlife; and
(cc)the impacts of roads and traffic on habitat connectivity for terrestrial and aquatic species; and
(II)solutions and best practices for—
(aa)reducing wildlife-vehicle collisions; and
(bb)improving habitat connectivity for terrestrial and aquatic species.
(B)In carrying out the study, the Secretary shall—
(i)conduct a thorough review of research and data relating to—
(I)wildlife-vehicle collisions; and
(II)habitat fragmentation that results from transportation infrastructure;
(ii)survey current practices of the Department of Transportation and State departments of transportation to reduce wildlife-vehicle collisions; and
(iii)consult with—
(I)appropriate experts in the field of wildlife-vehicle collisions; and
(II)appropriate experts on the effects of roads and traffic on habitat connectivity for terrestrial and aquatic species.
(3)(A)Not later than 18 months after the date of enactment of the Surface Transportation Reauthorization Act of 2021, the Secretary shall submit to Congress a report on the results of the study.
(B)The report under subparagraph (A) shall include—
(i)a description of—
(I)the causes of wildlife-vehicle collisions;
(II)the impacts of wildlife-vehicle collisions; and
(III)the impacts of roads and traffic on—
(aa)species listed as threatened species or endangered species under the Endangered Species Act of 1973 (16 U.S.C. 1531 et seq.);
(bb)species identified by States as species of greatest conservation need;
(cc)species identified in State wildlife plans; and
(dd)medium and small terrestrial and aquatic species;
(ii)an economic evaluation of the costs and benefits of installing highway infrastructure and other measures to mitigate damage to terrestrial and aquatic species, including the effect on jobs, property values, and economic growth to society, adjacent communities, and landowners;
(iii)recommendations for preventing wildlife-vehicle collisions, including recommended best practices, funding resources, or other recommendations for addressing wildlife-vehicle collisions; and
(iv)guidance, developed in consultation with Federal land management agencies and State departments of transportation, State fish and wildlife agencies, and Tribal governments that agree to participate, for developing, for each State that agrees to participate, a voluntary joint statewide transportation and wildlife action plan—
(I)to address wildlife-vehicle collisions; and
(II)to improve habitat connectivity for terrestrial and aquatic species.
(b)(1)Not later than 3 years after the date of enactment of the Surface Transportation Reauthorization Act of 2021, the Secretary shall, based on the study conducted under subsection (a), develop a series of in-person and online workforce development and technical training courses—
(A)to reduce wildlife-vehicle collisions; and
(B)to improve habitat connectivity for terrestrial and aquatic species.
(2)The Secretary shall—
(A)make the series of courses developed under paragraph (1) available for transportation and fish and wildlife professionals; and
(B)update the series of courses not less frequently than once every 2 years.
(c)(1)(A)The Secretary, acting through the Administrator of the Federal Highway Administration (referred to in this subsection as the “Secretary”), shall develop a quality standardized methodology for collecting and reporting spatially accurate wildlife collision and carcass data for the National Highway System, considering the practicability of the methodology with respect to technology and cost.
(B)In developing the standardized methodology under subparagraph (A), the Secretary shall—
(i)survey existing methodologies and sources of data collection, including the Fatality Analysis Reporting System, the General Estimates System of the National Automotive Sampling System, and the Highway Safety Information System; and
(ii)to the extent practicable, identify and correct limitations of those existing methodologies and sources of data collection.
(C)In developing the standardized methodology under subparagraph (A), the Secretary shall consult with—
(i)the Secretary of the Interior;
(ii)the Secretary of Agriculture, acting through the Chief of the Forest Service;
(iii)Tribal, State, and local transportation and wildlife authorities;
(iv)metropolitan planning organizations (as defined in section 134(b));
(v)members of the American Association of State Highway Transportation Officials;
(vi)members of the Association of Fish and Wildlife Agencies;
(vii)experts in the field of wildlife-vehicle collisions;
(viii)nongovernmental organizations; and
(ix)other interested stakeholders, as appropriate.
(2)The Secretary shall—
(A)develop a template for State implementation of a standardized national wildlife collision and carcass data system for the National Highway System that is based on the standardized methodology developed under paragraph (1); and
(B)encourage the voluntary implementation of the template developed under subparagraph (A).
(3)(A)The Secretary shall submit to Congress a report describing the standardized methodology developed under paragraph (1) not later than the later of—
(i)the date that is 18 months after the date of enactment of the Surface Transportation Reauthorization Act of 2021; and
(ii)the date that is 180 days after the date on which the Secretary completes the development of the standardized methodology.
(B)Not later than 4 years after the date of enactment of the Surface Transportation Reauthorization Act of 2021, the Secretary shall submit to Congress a report describing—
(i)the status of the voluntary implementation of the standardized methodology developed under paragraph (1) and the template developed under paragraph (2)(A);
(ii)whether the implementation of the standardized methodology developed under paragraph (1) and the template developed under paragraph (2)(A) has impacted efforts by States, units of local government, and other entities—
(I)to reduce the number of wildlife-vehicle collisions; and
(II)to improve habitat connectivity;
(iii)the degree of the impact described in clause (ii); and
(iv)the recommendations of the Secretary, including recommendations for further study aimed at reducing motorist collisions involving wildlife and improving habitat connectivity for terrestrial and aquatic species on the National Highway System, if any.
(d)The Secretary shall—
(1)establish guidance, to be carried out by States on a voluntary basis, that contains a threshold for determining whether a highway shall be evaluated for potential mitigation measures to reduce wildlife-vehicle collisions and increase habitat connectivity for terrestrial and aquatic species, taking into consideration—
(A)the number of wildlife-vehicle collisions on the highway that pose a human safety risk;
(B)highway-related mortality and the effects of traffic on the highway on—
(i)species listed as endangered species or threatened species under the Endangered Species Act of 1973 (16 U.S.C. 1531 et seq.);
(ii)species identified by a State as species of greatest conservation need;
(iii)species identified in State wildlife plans; and
(iv)medium and small terrestrial and aquatic species; and
(C)habitat connectivity values for terrestrial and aquatic species and the barrier effect of the highway on the movements and migrations of those species.

Legislative History

Notes & Related Subsidiaries

Editorial Notes

References in Text

The date of enactment of the Surface Transportation Reauthorization Act of 2021, referred to in subsecs. (a)(3)(A), (b)(1), and (c)(3), is the date of enactment of div. A of Pub. L. 117–58, which was approved Nov. 15, 2021. The Endangered Species Act of 1973, referred to in subsecs. (a)(3)(B)(i)(III)(aa) and (d)(1)(B)(i), is Pub. L. 93–205, Dec. 28, 1973, 87 Stat. 884, which is classified principally to chapter 35 (§ 1531 et seq.) of Title 16, Conservation. For complete classification of this Act to the Code, see

Short Title

note set out under section 1531 of Title 16 and Tables.

Statutory Notes and Related Subsidiaries

Effective Date

Section effective Oct. 1, 2021, see section 10003 of Pub. L. 117–58, set out as an

Effective Date

of 2021 Amendment note under section 101 of this title.

Reference

Citations & Metadata

Citation

23 U.S.C. § 172

Title 23Highways

Last Updated

Apr 6, 2026

Release point: 119-73