---
kind: "section"
citation: "23 U.S.C. § 172"
title: "23"
title_heading: "Highways"
number: "172"
heading: "Wildlife-vehicle collision reduction and habitat connectivity improvement"
release: "119-102"
date: "2026-07-12"
url: "https://uscodex.org/usc/23/172"
units:
  - "Chapter 1 — Federal-Aid Highways"
---

# §172. Wildlife-vehicle collision reduction and habitat connectivity improvement

- (a) **Study.—**
  - (1) **In general.—** The [Secretary](/usc/23/101.md?p=a-27) shall conduct a study (referred to in this subsection as the “study”) of the [state](/usc/23/101.md?p=a-28), 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) **Contents.—**
    - (A) **Areas of study.—** 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) **Methods.—** In carrying out the study, the [Secretary](/usc/23/101.md?p=a-27) 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) **Report.—**
    - (A) **In general.—** Not later than 18 months after the date of enactment of the Surface Transportation Reauthorization Act of 2021, the [Secretary](/usc/23/101.md?p=a-27) shall submit to Congress a report on the results of the study.
    - (B) **Contents.—** The report under [subparagraph (A)](#a-3-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](/usc/16/1531.md) et seq.);
          - (bb) species identified by [States](/usc/23/101.md?p=a-28) as species of greatest conservation need;
          - (cc) species identified in [State](/usc/23/101.md?p=a-28) wildlife plans; and
          - (dd) medium and small terrestrial and aquatic species;
      - (ii) an economic evaluation of the costs and benefits of installing [highway](/usc/23/101.md?p=a-11) 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](/usc/23/101.md?p=a-28) fish and wildlife agencies, and Tribal governments that agree to participate, for developing, for each [State](/usc/23/101.md?p=a-28) 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) **Workforce Development and Technical Training.—**
  - (1) **In general.—** Not later than 3 years after the date of enactment of the Surface Transportation Reauthorization Act of 2021, the [Secretary](/usc/23/101.md?p=a-27) shall, based on the study conducted under [subsection (a)](#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) **Availability.—** The [Secretary](/usc/23/101.md?p=a-27) shall—
    - (A) make the series of courses developed under [paragraph (1)](#b-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) **Standardization of Wildlife Collision and Carcass Data.—**
  - (1) **Standardized methodology.—**
    - (A) **In general.—** The [Secretary](/usc/23/101.md?p=a-27), acting through the Administrator of the Federal [Highway](/usc/23/101.md?p=a-11) Administration (referred to in this subsection as the “[Secretary](/usc/23/101.md?p=a-27)”), shall develop a quality standardized methodology for collecting and reporting spatially accurate wildlife collision and carcass data for the [National Highway System](/usc/23/101.md?p=a-16), considering the practicability of the methodology with respect to technology and cost.
    - (B) **Methodology.—** In developing the standardized methodology under [subparagraph (A)](#c-1-A), the [Secretary](/usc/23/101.md?p=a-27) 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](/usc/23/101.md?p=a-11) Safety Information System; and
      - (ii) to the extent practicable, identify and correct limitations of those existing methodologies and sources of data collection.
    - (C) **Consultation.—** In developing the standardized methodology under [subparagraph (A)](#c-1-A), the [Secretary](/usc/23/101.md?p=a-27) shall consult with—
      - (i) the [Secretary](/usc/23/101.md?p=a-27) of the Interior;
      - (ii) the [Secretary](/usc/23/101.md?p=a-27) of Agriculture, acting through the Chief of the Forest Service;
      - (iii) Tribal, [State](/usc/23/101.md?p=a-28), and local transportation and wildlife authorities;
      - (iv) metropolitan planning organizations (as defined in [section 134(b)](/usc/23/134.md?p=b));
      - (v) members of the American Association of [State](/usc/23/101.md?p=a-28) [Highway](/usc/23/101.md?p=a-11) 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) **Standardized national data system with voluntary template implementation.—** The [Secretary](/usc/23/101.md?p=a-27) shall—
    - (A) develop a template for [State](/usc/23/101.md?p=a-28) implementation of a standardized national wildlife collision and carcass data system for the [National Highway System](/usc/23/101.md?p=a-16) that is based on the standardized methodology developed under [paragraph (1)](#c-1); and
    - (B) encourage the voluntary implementation of the template developed under [subparagraph (A)](#c-2-A).
  - (3) **Reports.—**
    - (A) **Methodology.—** The [Secretary](/usc/23/101.md?p=a-27) shall submit to Congress a report describing the standardized methodology developed under [paragraph (1)](#c-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](/usc/23/101.md?p=a-27) completes the development of the standardized methodology.
    - (B) **Implementation.—** Not later than 4 years after the date of enactment of the Surface Transportation Reauthorization Act of 2021, the [Secretary](/usc/23/101.md?p=a-27) shall submit to Congress a report describing—
      - (i) the status of the voluntary implementation of the standardized methodology developed under [paragraph (1)](#c-1) and the template developed under [paragraph (2)(A)](#c-2-A);
      - (ii) whether the implementation of the standardized methodology developed under [paragraph (1)](#c-1) and the template developed under [paragraph (2)(A)](#c-2-A) has impacted efforts by [States](/usc/23/101.md?p=a-28), 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)](#c-3-B-ii); and
      - (iv) the recommendations of the [Secretary](/usc/23/101.md?p=a-27), 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](/usc/23/101.md?p=a-16), if any.
- (d) **National Threshold Guidance.—** The [Secretary](/usc/23/101.md?p=a-27) shall—
  - (1) establish guidance, to be carried out by [States](/usc/23/101.md?p=a-28) on a voluntary basis, that contains a threshold for determining whether a [highway](/usc/23/101.md?p=a-11) 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](/usc/23/101.md?p=a-11) that pose a human safety risk;
    - (B) [highway](/usc/23/101.md?p=a-11)-related mortality and the effects of traffic on the [highway](/usc/23/101.md?p=a-11) on—
      - (i) species listed as endangered species or threatened species under the Endangered Species Act of 1973 ([16 U.S.C. 1531](/usc/16/1531.md) et seq.);
      - (ii) species identified by a [State](/usc/23/101.md?p=a-28) as species of greatest conservation need;
      - (iii) species identified in [State](/usc/23/101.md?p=a-28) 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](/usc/23/101.md?p=a-11) on the movements and migrations of those species.

## Source credit

(Added Pub. L. 117–58, div. A, title I, § 11123(c)(1), Nov. 15, 2021, 135 Stat. 502.)

## Notes

### 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.