23 C.F.R. § 420.115
(c) A project agreement must be executed by the State DOT and the FHWA Division Office for each statewide transportation planning, metropolitan planning area, or RD&T work program, individual activity or study, or any combination administered as a single Federal-aid project. The project agreement may be executed concurrent with or after authorization has been given by the FHWA Division Administrator to proceed with the work in whole or in part. In the event that the project agreement is executed for only part of the work, the project agreement must be amended when authorization is given to proceed with additional work.
(The information collection requirements in § 420.115(c) have been approved by the OMB and assigned control numbers 2125-0529)