traffic safety grants (liquidation of contract authorization) (limitation on obligations) (highway trust fund) For payment of obligations incurred in carrying out provisions of 23 U.S.C. 402 , 404 and 405, and section 4001(a)(6) of the Fixing America's Surface Transportation Act, to remain available until expended, $597,629,000, to be derived from the Highway Trust Fund (other than the Mass Transit Account): Provided , That none of the funds in this Act shall be available for the planning or execution of programs the total obligations for which, in fiscal year 2018, are in excess of $597,629,000 for programs authorized under 23 U.S.C. 402 , 404 and 405, and section 4001(a)(6) of the Fixing America's Surface Transportation Act, of which $261,200,000 shall be for Highway Safety Programs under 23 U.S.C. 402