| Subject/Title | 
        Resource URL | 
    
    
        | Title 23: Highways | 
    
    
        | Chapter 1 – Federal-Aid Highways, Sec. 109 – Standards | 
        23 U.S.C. 109 | 
    
    
        | 23 CFR Part 771 Interim Final Rule (July 3, 2025) | 
        Interim Final Rule | 
    
    
        | Environmental Impact and Related Procedures | 
        23 CFR 771 | 
    
    
        | Preamble to the Regulation on Environmental Impact and Related Procedures (March 24, 2009) | 
        Preamble | 
    
    
        | Preamble to the Regulation on Environmental Impact Statements and Related Documents (August 28, 1987) | 
        Preamble | 
    
    
        | Procedures for Abatement of Highway Traffic Noise and Construction Noise | 
        23 CFR 772 | 
    
    
        | Parks, Recreation Areas, Wildlife and Waterfowl Refuges and Historic Sites (Section 4(f)) | 
        23 CFR 774 | 
    
    
        | Mitigation of Impacts to Wetlands and Natural Habitat | 
        23 CFR 777 | 
    
    
        | Establishing Discipline and Accountability in the Environmental Review and Permitting Process for Infrastructure Projects | 
        E.O. 13807 | 
    
    
        | Expediting Environmental Reviews and Approvals for High Priority Infrastructure Projects | 
        E.O. 13766 | 
    
    
        | Environmental Stewardship and Transportation Infrastructure Project Reviews | 
        E.O. 13274 | 
    
    
        | Subject/Title | 
        Resource URL | 
    
    
        | Fixing America’s Transportation (FAST) Act | 
    
    
        | In-Depth Questions and Answers on the changes to 23 U.S.C. § 139 as they relate to FHWA, FRA, and FTA projects – SUPERSEDED BY: THE REVISED SECTION 139 GUIDANCE | 
        Q&A – SUPERSEDED | 
    
    
        | Questions and Answers on the Applicability of 23 U.S.C. § 139 to FHWA, FRA, and FTA Projects | 
        Q&A | 
    
    
        | Changes to 23 U.S.C. §§ 326 and 327 through Implementation of Sections 1307 and 1308 of the Fixing America's    Surface Transportation (FAST) Act | 
        Memorandum | 
    
    
        | Categorical Exclusion for Projects of Limited Federal Assistance | 
        Guidance | 
    
    
        | Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) | 
    
    
        | Environmental Review Process Final Guidance – SUPERSEDED BY: Section 139 Efficient Environmental Reviews for Project Decisionmaking and One Federal Decision Interim Final Guidance | 
        Guidance – SUPERSEDED | 
    
    
    | Section 139 Efficient Environmental Reviews for Project Decisionmaking and One Federal Decision | 
    | Section 139 Notice of Availability | 
    Notice of Availability | 
    | Section 139 Efficient Environmental Reviews for Project Decisionmaking and One Federal Decision Interim Final Guidance | 
    Guidance | 
    | Section 139 Environmental Impact Statement (EIS) Process Chart | 
    EIS Process Chart | 
    | Section 139 Environmental Assessment (EA) Process Chart | 
    EA Process Chart | 
    
        | Other Guidance | 
    
    
        | Clarifying Fiscal Constraint Guidance | 
        Memorandum | 
    
    
        | Guidance on Financial Planning and Fiscal Constraints for Transportation Plans and Programs | 
        Memorandum | 
    
     
        | Guidance on Purpose and Need | 
        Memorandum | 
    
      
        | NEPA Re-Evaluation Joint Guidance for FHWA, FRA, & FTA | 
        Guidance | 
    
    
        | Interim Guidance on the Application of Travel and Land Use Forecasting in NEPA | 
        Guidance | 
    
    
        | TECHNICAL ADVISORY (T 6640.8A): Guidance for Preparing and Processing Environmental and Section 4(f) Documents | 
        Guidance | 
    
    
        | The Development of Logical Project Termini | 
        Guidance | 
    
    
        | Additional Flexibilities in Developing Categorical Exclusions (May 2017) | 
        Memorandum | 
    
    
        | Additional Flexibilities in Developing Categorical Exclusions (June 2018) | 
        Memorandum | 
    
    
        | The Importance of Purpose and Need in Environmental Documents | 
        Guidance | 
    
    
        | Guidance on FHWA Prior Concurrence Procedures for EISs | 
        Guidance |