; (3) for fiscal year 2024, $12,500,000 shall be used to carry out projects under subsection (b)(2)(A) and $22,500,000 shall be used to carry out projects under subsection (b)(2)(B); and (4) for fiscal year 2025, $10,000,000 shall be used to carry out projects under subsection (b)(2)(A) and $25,000,000 shall be used to carry out projects under subsection (b)(2)(B). (k) Funding flexibility Funds made available in a fiscal year for making grants for projects under subsection (b)(2) that are not expended in such fiscal year may be made available in the following fiscal year for projects under such subsection or for the national surface transportation system funding pilot under section 5402 of the INVEST in America Act . . 5402. National surface transportation system funding pilot (a) Establishment (1) In general The Secretary of Transportation, in coordination with the Secretary of the Treasury, shall establish a pilot program to demonstrate a national motor vehicle per-mile user fee to restore and maintain the long-term solvency of the Highway Trust Fund and achieve and maintain a state of good repair in the surface transportation system. (2) Objectives The objectives of the pilot program are to— (A) test the design, acceptance, implementation, and financial sustainability of a national per-mile user fee; (B) address the need for additional revenue for surface transportation infrastructure and a national per-mile user fee; and (C) provide recommendations regarding adoption and implementation of a national per-mile user fee. (b) Parameters In carrying out the pilot program established under subsection (a), the Secretary of Transportation, in coordination with the Secretary of the Treasury, shall— (1) provide different methods that volunteer participants can choose from to track motor vehicle miles traveled; (2) solicit volunteer participants from all 50 States and the District of Columbia; (3) ensure an equitable geographic distribution by population among volunteer participants