The National Environmental Policy Act of 1969 (NEPA; 42 U.S.C. 4321 – 4336e) requires Federal agencies to assess the reasonably foreseeable environmental effects of any proposed major Federal actions. Major Federal actions are those that are subject to substantial Federal control and responsibility. Federal agencies must evaluate whether a major Federal action is likely to have reasonably foreseeable significant effects and conduct an appropriate level of NEPA review based on the evaluation. 

NEPA is a procedural law rather than a substantive law, meaning that it defines a process that Federal agencies must follow but does not dictate the result of that process. All Federal agencies are responsible for following the NEPA process.

NHTSA’s mission is to save lives, prevent injuries, and reduce economic costs due to road traffic crashes through education, research, safety standards, and enforcement. NEPA applies to all elements of NHTSA’s major Federal actions, including but not limited to, new or revised agency rules and regulations, as well as projects and programs that are entirely or partly financed, assisted, conducted, regulated, or approved by NHTSA. NHTSA determines which agency actions are subject to NEPA requirements, per 42 U.S.C 4336e(10) and DOT Order 5610.1D.

DOT Order 5610.1D, “Procedures for Considering Environmental Impacts,” effective July 1, 2025, describes DOT’s processes for complying with NEPA under 42 U.S.C. 4321 et seq. NHTSA has its own agency-specific requirements and processes for complying with NEPA at Subpart D of DOT Order 5610.1D. NHTSA evaluates the scope of each action to determine the appropriate level of NEPA review, as described in the sections below.  

Categorical Exclusions 

Categorical Exclusions (CEs) are categories of actions that an agency has determined normally do not significantly affect the quality of the human environment absent extraordinary circumstances. Extraordinary circumstances are factors or circumstances that indicate that a normally categorically excluded action is likely to have a reasonably foreseeable significant adverse impact and would require further environmental review.  

NHTSA is in the process of developing a list of CEs for the agency’s use. The CEs, once finalized, will be published in the Federal Register.  

Environmental Assessments 

NHTSA prepares Environmental Assessments (EAs) for proposed agency actions that do not have a reasonably foreseeable significant effect on the quality of the human environment, or if the significance of such effect is unknown. EAs conclude with a finding of no significant impact (FONSI) or determination that an environmental impact statement is necessary. The following principles apply to the development of an EA:  

• An EA must describe the purpose and need of the proposed action (42 U.S.C 4336a(d)).  
• An EA must be no more than 75 pages, not including any citations or appendices (42 U.S.C. 4336a(e)(2)).
• An EA must be completed within one year from the start of the EA to the completion of the final EA and Finding of No Significant Impact (FONSI) (42 U.S.C. 4336a(g)(1)(B)). 

In developing an EA, NHTSA evaluates all reasonable alternatives, including the proposed action and the no action alternative. NHTSA evaluates the potentially affected environment and degree of the impacts of the proposed action, discussing the impacts in proportion to their significance.    

NHTSA will notify the public of the availability of an EA and any accompanying FONSI. For rulemaking actions, NHTSA may include an EA in the regulatory notices and analyses section of the Advance Notice of Proposed Rulemaking, Notice of Proposed Rulemaking, supplemental Notice of Proposed Rulemaking, Direct Final Rule, or Interim Final Rule. 

Environmental Impact Statements  

NHTSA prepares environmental impact statements (EISs) for proposed actions requiring an environmental document that has a reasonably foreseeable significant effect on the quality of the human environment. An EIS is a more detailed environmental review documentation compared to a CE or an EA. The following principles apply to the development of an EIS:  

• An EIS must describe the purpose and need of the proposed action (42 U.S.C 4336a(d)).  
• An EIS must be no more than 150 pages, not including citations or appendices (42 U.S.C 4336a(e)(1)(A)). An EIS for a proposed agency action of extraordinary complexity must be no more than 300 pages, not including citations or appendices (42 U.S.C 4336a(e)(1)(B)).  
• A final EIS must be issued no later than two years after the issuance date of a notice of intent (NOI) (42 U.S.C 4336a(g)(1)(A)). 

As with an EA, NHTSA evaluates all reasonable alternatives, including the proposed action, and the no action alternative for an EIS NHTSA evaluates the potentially affected environment and degree of the impacts of the proposed action, and discusses impacts in proportion to their significance in the EIS.  

To formally initiate the EIS process, NHTSA publishes a notice of intent (NOI) to prepare an EIS in the Federal Register for public comment on alternatives, impacts, relevant information, studies, or analyses with respect to the proposed agency action (42 U.S.C 4336a(c)). NHTSA files EISs with the U.S. Environmental Protection Agency (EPA) in accordance with EPA filing guidance. The draft EIS is published for public review and comment on NHTSA’s website, in the appropriate docket, and on e-NEPA. Substantive comments received on a draft EIS are responded to and included in the final EIS.

For questions about NHTSA’s NEPA program, please reach out to: nhtsa.nepa_mailing@dot.gov.    

Last updated: July 24, 2025