There are three classes of actions that prescribe the level of documentation required in the NEPA process. In selecting the class of action, the Administration may make use of any reliable data source and is not required to undertake new scientific or technical research unless the new scientific or technical research is essential to a reasoned choice among alternatives, and the overall costs and time frame of obtaining it are not unreasonable. A programmatic approach may be used for any class of action.

(a) EIS. Actions that have a reasonably foreseeable significant effect on the quality of the human environment require an EIS. The following are examples of actions that normally require an EIS:

(1) A new controlled access freeway.

(2) A highway project of four or more lanes on a new location.

(3) Construction or extension of a fixed transit facility (e.g., rapid rail, light rail, commuter rail, bus rapid transit) that will not be located primarily within an existing transportation right-of-way.

(4) New construction or extension of a separate roadway for buses or high occupancy vehicles not located within an existing transportation right-of-way.

(5) New construction or extension of a separate roadway for buses not located primarily within an existing transportation right-of-way.

(6) New construction of major railroad lines or facilities (e.g., terminal passenger stations, freight transfer yards, or railroad equipment maintenance facilities) that will not be located within an existing transportation right-of-way.

(b) CE. Actions that normally do not have a significant environmental effect are excluded from the requirement to prepare an EA or EIS. A specific list of CEs normally not requiring NEPA documentation is set forth in § 771.117(c) for FHWA actions or § 771.118(c) for FTA actions. When appropriately documented, additional projects may also qualify as CEs pursuant to § 771.117(d) for FHWA actions or pursuant to § 771.118(d) for FTA actions. FRA's CEs are listed in § 771.116.

(c) EA. Actions that do not have reasonably foreseeably significant effects on the quality of the human environment or for which the significance of the environmental impact is unknown. All actions that are not EISs or CEs are EAs. All actions in this class require the preparation of an EA to determine the appropriate environmental document required.