Location and Environment

Iowa Highway


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.

  1. 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 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.
  2. 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 impact will occur; an environmental impact statement will be prepared.

  3. Categorical exclusions (CEs) are issued for actions that do not individually or cumulatively have a significant effect on the environment.

    23 CFR 771.115