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Environmental Resources Information

What environmental resources are considered under NEPA?

The NEPA document should focus on those environmental resources that have been identified as significant based on the scoping process, where potentially significant impacts may result, and where data are needed to comply with other applicable environmental laws, regulations, and executive orders. The level of detail for each resource should be in proportion to the significance of the potential impact, and the potential it has to affect the decision-making process for alternative selection.

The table below highlights the environmental resources and impact areas that may need to be considered as part of the environmental review process for FTA projects. See the Environmental Training and Technical Assistance page for information on training opportunities related to specific resource areas.

Resource Area Description Additional Information
Acquisitions and Relocations

If land is to be acquired for a transit project, the project’s environmental documentation should contain a description of the land. In cases where an acquisition requires the displacement of businesses or individuals, the social impact will be analyzed as part of the environmental review process. This analysis should identify the characteristics and needs of persons and businesses to be displaced, describe inventory availability of comparable replacement dwellings and sites, discuss potential relocation problems, and describe methods to mitigate adverse impacts.

FTA-funded projects must also comply with the Uniform Relocation Assistance and Real Property Acquisition Policies Act (42 U.S.C. § 61). Federal regulations implementing the Uniform Act are contained in 49 CFR part 24.

More information on real property acquisition as it relates to the environmental review process can be found in these FAQs.

Guidance on the Uniform Act as it pertains to FTA programs and projects is contained in Chapter IV, Project Management, of FTA Circular 5010.1E, Grant Management Requirements (July 16, 2018).

FTA Final Guidance on the Application of 49 U.S.C. § 5323(q) to Corridor Preservation for a Transit Project.

Dear Colleague Letter:  Real Estate and NEPA (July 2022) – a reminder of FTA’s policies on the acquisition of real property where Federal funds will be, or are anticipated to be, used for the purchase or development of that property.

Early/Advance Property Acquisition and NEPA Webinar (passcode: X3&1Wdd.) (December 2022) –provides an overview of FTA policies on early or advance acquisition of real property for instances where federal funds will be, or are anticipated to be, used for the purchase or development of the subject property. The webinar also addresses compliance with the Uniform Act. The presentation slides  are available for download.

See FTA’s Real Estate page for additional information.

Air Quality

FTA-funded projects must meet the requirements of the Clean Air Act (42 U.S.C. § 7401 et seq.) under the NEPA process. The purpose of the Clean Air Act is to protect and enhance air quality to promote public health and welfare of the nation. To accomplish this, the Act addresses criteria air pollutants that are regulated through the National Ambient Air Quality Standards (NAAQS).

The Clean Air Act requires that, in areas experiencing air quality problems, transportation planning and projects must be consistent with – or conform to – air quality goals established in a state air quality implementation plan, or SIP.

Another applicable air quality program is the Congestion Mitigation and Air Quality Improvement Program (CMAQ). The CMAQ program provides funding to areas that face the challenge of attaining or maintaining the NAAQS for ozone, carbon monoxide, and/or particulate matter. 

More information about air quality conformity is available here.

Additional transportation conformity policy and guidance documents can be found on EPA's webpage and FHWA’s air quality webpage.

Clarification of Transportation Conformity Requirements for FHWA/FTA Projects Requiring Environmental Impact Statements (May 2003).

Greenhouse Gas Emissions from Transit Projects: Programmatic Assessment (Report 0263) - This programmatic assessment is a NEPA streamlining tool that serves to (1) report on whether certain types of proposed transit projects merit detailed analysis of their greenhouse gas (GHG) emissions at the project level and (2) be a source of data and analysis for FTA and its grantees to reference in future environmental documents for projects in which detailed, project-level GHG analysis is not vital. This programmatic assessment updates and supersedes the 2017 Greenhouse Gas Emissions from Transit Projects: Programmatic Assessment (Report 0097).

FTA's Transit Greenhouse Gas Emissions Estimator is a spreadsheet tool that allows users to estimate the partial lifecycle GHG emissions generated from the construction, operations, and maintenance phases of projects across select transit modes.

Biological Resources

Project sponsors must consider the effects of a proposed project on protected wildlife and plant species and/or their habitats as part of the NEPA process to comply with Federal laws, including the Endangered Species Act of 1973, Migratory Bird Treaty Act, Bald and Golden Eagle Protection Act, Magnuson-Stevens Fishery Conservation and Management Act, the Marine Mammal Protection Act of 1972, and Executive Order 13112 Invasive Species.

SOP No. 23 Biological Resources contains guidance on coordination and documentation requirements for projects affecting listed or protected wildlife, plants, fish, birds, reptiles, amphibians, marine mammals and their habitats.

Programmatic Biological Opinion for Transportation Projects in the Range of the Indiana Bat and Northern Long-Eared Bat (February 2018)

Community Impacts

Transit projects may affect the social environment in several ways and change the physical layout, demographics, and sense of neighborhood in local communities. As part of the NEPA process, project sponsors should work with local planning agencies and conduct public outreach to determine the impacts a proposed project may have on communities and identify methods to avoid, minimize, and mitigate impacts. Specific community impacts may include physical and psychological barriers, changes in land use patterns, a change in access to services, changes in population densities, and disruptions to neighborhood cohesiveness.

Economic Impacts

Proposed transit projects may have economic impacts that should be included in the environmental review document. Projects may create direct and indirect taxation changes, cause substantial displacement of businesses and individuals, disrupt business activities, and influence regional construction costs. There may also be economic benefits of a project including accessibility to markets and job creation.

Energy Conservation

NEPA requires that, as part of the discussion of environmental consequences, energy requirements and conservation potential be included (40 CFR 1502.16(a)(6)).

Environmental Justice

Executive Order 12898, Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations (February 11, 1994), requires FTA to make environmental justice part of the agency’s mission by identifying and addressing disproportionately high and adverse human health and environmental effects of FTA programs, policies, and projects on minority populations and low-income populations. Collectively, these populations are referred to as EJ populations.

FTA funding recipients are required to incorporate EJ principles into transportation planning and decision-making processes as well as project-specific environmental reviews.

FTA’s Environmental Justice Circular implementing Executive Order 12898 is meant to ensure that FTA funding recipients avoid, minimize, or mitigate disproportionately high and adverse health and environmental effects, including social and economic effects, on minority populations and low-income populations, consistent with the U.S. DOT’s EJ Order and CEQ’s guidance.

An FTA FAQ provides additional clarification on EJ analysis and requirements.

Geology and Soils

The environmental analysis for transit projects should consider the geologic and soil conditions (including hazard areas) in the vicinity of the project area. The documentation should include a discussion on the potential significant adverse construction and operational impacts of the project alternatives on these conditions, as well as potential impacts of identified geologic hazards on the project alternatives.

Hazardous Substances and Brownfields

Transit projects may encounter hazardous materials during construction, especially if a project is built on a brownfield or a previously disturbed site. “Hazardous substance” is a broad term that includes all substances that can be harmful to people or the environment. The discovery of hazardous materials within a proposed project area may have an adverse impact on timely completion of the project. Project sponsors must ensure proper due diligence prior to selecting and purchasing properties through an assessment of potential contamination during the environmental review process.  

SOP No. 19 Consideration of Contaminated Properties including Brownfields provides guidance on assessment and acquisition considerations for property that is or may be contaminated.

Additional guidance is available as follows:

Historic and Archeological Resources

Section 106 of the National Historic Preservation Act and its implementing regulations (36 CFR part 800) require Federal agencies to consider the effects of their undertakings on historic properties and to seek out consulting parties to request their views and participate in consultation regarding a project's effect on historic properties before Federal funds are committed or a license is issued for a project.  The goal of the consultation is to identify historic properties potentially affected by the undertaking, assess its effects, and seek ways to avoid, minimize, or mitigate any adverse effects on historic properties.

SOP No. 21 Section 106 Process contains guidance on roles, responsibilities, and consultation procedures in the Section 106 process.

In 2018, the Advisory Council on Historic Preservation (ACHP), in coordination with US DOT, issued a "Program Comment to Exempt Consideration of Effects to Rail Properties within Rail Rights-of-Ways" to accelerate Section 106 reviews for certain activities affecting rail properties located within railroad and rail transit ROW. More information on the program comment is available here.

Land Use and Development

Transit projects need to be consistent with official plans for the comprehensive development of an area, as well as with a community’s goals and objectives. The environmental analysis should consider the compatibility of the project with local and State plans and zoning regulations.

If a proposed project alternative alignment would not be compatible with surrounding land uses or would encourage land use and development inconsistent with local plans, goals, and objectives, the expected impacts on the area and a discussion of alternative locations should be presented in the environmental analysis. In addition, documentation should identify measures that would be used to mitigate any anticipated adverse impacts.

FTA’s Transportation Planning webpage and the Transit-Oriented Development webpage for additional information.

Noise and Vibration

Noise and vibration are sometimes among the major concerns regarding the effects of a transit project on the surrounding community and are key elements of the environmental impact assessment process for public transportation projects. A transit system is often placed near population centers by necessity and may cause noise and vibration at nearby residences and other sensitive types of land use.

FTA’s Transit Noise and Vibration Impact Assessment Manual provides guidance on how to assess noise and vibration impacts of proposed public transit projects, and includes a range of measures for controlling excessive noise and vibration.

The procedures for a General Noise Assessment are incorporated in a spreadsheet program (MS Excel) that allows users to readily predict noise levels from a proposed project and assess impact based on FTA’s noise impact criteria.

Public Involvement

FTA’s environmental impact procedures require project sponsors to conduct early coordination and public involvement throughout project development (23 CFR 771.111). In addition, EAs and EISs have specific public involvement requirements. Establishing a meaningful public involvement process is a strategic effort that sometimes requires assembling a selection of techniques.

See SOP No. 11 Receiving and Responding to Public and Agency Comments and other relevant SOPs for more.

The USDOT’s Promising Practices for Meaningful Public Involvement in Transportation Decision-Making guide provides strategies for meaningful engagement. (October 2022).

Safety and Security

Safety and security should be addressed in a project’s environmental document when appropriate for the specific project. Projects should be evaluated to identify potential pedestrian and traffic hazards, as well as user and employee security issues.

See FTA’s Transit Safety and Oversight webpage for more information.

Section 4(f) Requirements

Section 4(f) requirements (23 CFR part 774) prohibit USDOT agencies, including FTA, from using land from publicly owned parks, recreation areas (including recreational trails), wildlife and water fowl refuges, or land from public and private historic properties. Use may only be permitted if there is no feasible and prudent alternative to that use, and the action includes all possible planning to minimize harm to the property resulting from such a use.

SOP No. 18 Section 4(f) Evaluations contains guidance on FTA’s roles and responsibilities and aligning Section 4(f) with NEPA.

FHWA Section 4(f) Policy Paper, adopted by FTA as guidance (per November 9, 2012 memo)

FTA adopted two of FHWA’s nationwide Section 4(f) programmatic evaluations (effective on January 7, 2021) for certain transportation projects:  the Nationwide Net Benefit Programmatic Evaluation and the Nationwide Historic Bridges Programmatic Evaluation  (per December 8, 2020 Federal Register notice).

Transportation Impacts

By definition, any proposed transit project will potentially influence elements of the local transportation system, including transit facilities and services, road traffic patterns and volumes, and parking. Environmental documents for transit projects should include a discussion of potential transportation impacts and their impact on the environment, human and natural, as applicable.

More guidance on transportation impacts is available here.

Water Resources

FTA-funded projects or actions affecting water resources, including coastal zones, floodplains, navigable waterways, water quality and stormwater, wetlands and other waters of the U.S. must comply with applicable Federal requirements. Such requirements include the Clean Water Act (33 U.S.C. § 1344), Rivers and Harbors Act of 1899 (33 U.S.C. § 401 et seq.), Executive Order 11990—Protection of Wetlands, U.S. DOT Order 5660.1A—Preservation of the Nation's Wetlands, Executive Order 11988— Floodplain Management, U.S. DOT Order 5650.2—Floodplain Management and Protection, Coastal Zone Management Act of 1972 (16 U.S.C. § 1451 et seq.), Coastal Barrier Resources Act of 1982 (16 U.S.C. § 3501 et seq.), Wild and Scenic Rivers Act of 1968 (16 U.S.C. § 1271-1287), and the Safe Drinking Water Act (42 U.S.C. § 300f et seq.).

SOP No. 22 Water Resources provides guidance on the analysis required for projects or actions affecting water resources to comply with Federal environmental requirements.


Transit projects may impact utilities by requiring utility relocation or adjustment of utility lines and facilities. Coordination with utility providers, such as the local electricity or telecommunications providers, should occur during the environmental review process to minimize service disruption later.