The Section 139 Environmental Review Process: Efficient Environmental Reviews for Project Decisionmaking and One Federal Decision Interim Final Guidance provides project sponsors with information concerning the statutory framework at 23 U.S.C. 139 applicable to the Agencies’ environmental review processes. The guidance supersedes and replaces the “Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) Environmental Review Process Final Guidance” that was jointly issued by FHWA and FTA in November of 2006. The Interim Final Guidance covers numerous statutory changes to the Section 139 environmental review process made by the Moving Ahead for Progress in the 21st Century Act (MAP-21), the Fixing America's Surface Transportation (FAST) Act, and the Bipartisan Infrastructure Law (BIL).

Refer to the accompanying process charts for an overview of the environmental review process for a major project EIS and an EA.