Office of Location and Environment

Primary Projects

Transportation projects vary in type, size, complexity, and potential to affect the human and natural environment. To account for the variability of project impacts, three basic "classes of action" are allowed and determine how compliance with NEPA is carried out and documented.

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Environmental impact statement

Transportation projects vary in type, size, complexity, and potential to affect the human and natural environment. To account for the variability of project impacts, three basic "classes of action" are allowed and determine how compliance with NEPA is carried out and documented.

An environmental impact statement (EIS) is prepared for projects where it is known that the action will have a significant effect on the environment. The following are examples of actions that normally require an EIS.

  • A new controlled access freeway.
  • A highway project of four or more lanes on a new alignment.
  • New construction or extension of fixed-rail transit facilities.
  • New construction or extension of a separate roadway for buses or high-occupancy vehicles not located within an existing highway facility.
  • 23 CFR 771.115
    23 CFR 771.123

Environmental assessment

An environmental assessment (EA) is prepared for actions in which the significance of the environmental impact is not clearly established. Should environmental analysis and interagency review during the EA process find a project to have no significant impacts on the quality of the environment, a finding of no significant impact (FONSI) is issued. If during processing of the EA it is determined that significant impacts will occur; an environmental impact statement will be prepared.

    23 CFR 771.115
    23 CFR 771.119

Section 4(f)

The Department of Transportation Act (DOT Act) of 1966 included Section 4(f), a special provision which stipulated that the Federal Highway Administration (FHWA) and other DOT agencies cannot approve the use of land from significant publicly owned parks, recreational areas, wildlife and waterfowl refuges, or public and private historical sites unless the following conditions apply.
  • There is no feasible and prudent alternative to the use of land.
  • The action includes all possible planning to minimize harm to the property resulting from use. 
When a Section 4(f) document is prepared, impacts to 4(f) resources are addressed with either a; Section 4(f) statement, a programmatic Section 4(f) statement or a de minimus impact finding depending on the severity of impacts to a 4(f) resource.

de minimis impact is one that will not adversely affect the activities, features or attributes of the property. For historic sites, a de minimisimpact means that FHWA has determined (in accordance with 36 CFR Part 800) that either no historic property is affect by the project or that the project will have "no adverse effect" on the historic property. A de minimis impact determination does not require analysis to determine if avoidance alternatives are feasible and prudent, but consideration of avoidance, minimization, and mitigation or enhancement measures should occur. There are certain minimum coordination steps that are also necessary.
23 CFR 774