On approving a project grant application under this subchapter, the Secretary of Transportation shall offer the sponsor a grant to pay the United States Government’s share of the project costs allowable under
section 47110 of this title. The Secretary may impose terms on the offer that the Secretary considers necessary to carry out this subchapter and regulations prescribed under this subchapter. An offer shall state the obligations to be assumed by the sponsor and the maximum amount the Government will pay for the project from the amounts authorized under chapter 481 of this title (except sections 48102(e), 48106, 48107, and 48110). At the request of the sponsor, an offer of a grant for a project that will not be completed in one fiscal year shall provide for the obligation of amounts apportioned or to be apportioned to a sponsor under section 47114(c) or 47114(d)(2)(A) for the fiscal years necessary to pay the Government’s share of the cost of the project. An offer that is accepted in writing by the sponsor is an agreement binding on the Government and the sponsor. The Government may pay or be obligated to pay a project cost only after a grant agreement for the project is signed.