Guidance on Legal Sufficiency Criteria for Adequate Cumulative & Secondary Impacts Analysis in EIS Documents

Focus Area

Indirect Effects/Cumulative Impacts


Air Quality, Environmental Process




Under $99k



Research Idea Scope

TERI Administrator Note (January 2009): Funded as NCHRP Project 25-25, Task 43, “Guidance on legal sufficiency criteria for adequate cumulative and secondary impacts analysis in EIS documents.”  Report submitted September 2008.

Review latest information from FHWA and AASHTO and provide guidance to state DOTs.

To meet the requirements of the National Environmental Protection Act (NEPA), a transportation agency must evaluate the secondary and cumulative impacts of proposed transportation projects, along with the direct impacts, in Environmental Impact Statements or Environmental Assessments. The Council on Environmental Quality’s (CEQ) regulations for implementing the National Environmental Policy Act (NEPA) define cumulative effects as “the impact on the environment which results from the incremental impact of the action when added to other past, present, and reasonably foreseeable future actions regardless of what agency (Federal or non-federal) or person undertakes such other actions” (40 CFR ~ 1508.7). Secondary, or indirect, impacts are defined as “effects which are caused by the action and are later in time or farther removed in distance, but are still reasonably foreseeable.” (40 CFR 1508.8(b). In spite of these definitions, the legal sufficiency of many such analyses of indirect and cumulative impacts have been called into question by the courts. The objective of this project is to develop guidelines on the most effective ways to analyze cumulative and indirect impacts in the context of NEPA requirements.

Suggested By

SCOE 2004 Meeting