N.H. Rev. Stat. Ann. § 228:12-a

The department may use toll credits as a match for federal highway funds solely for the funding of highway and road projects, projects concerning the travel of motor vehicles on such highways and roads, and the completion of the project development phase of the project named Nashua-Manchester-Concord, project number 40818, in the 2019-2028 Ten Year Transportation Improvement Plan. Any other use of toll credits shall require approval of the joint legislative capital project overview committee, established in RSA 17-J:1, prior to moving the project forward for approval in the state 10-year transportation improvement program.