N.H. Rev. Stat. § 21-L:4

In addition to the powers, duties, and functions otherwise vested by law in the commissioner of the department of transportation, he shall: I. Represent the public interest in the administration of the functions of the department and be responsible to the governor, the general court, and the public for such administration. II. Consult regularly with regional planning commissions established pursuant to RSA 36:45-53 with regard to department planning activities. III. Provide for a support unit within his office which shall include the function of monitoring projects and conducting audits of department activities to insure compliance with state and federal contracts, laws, and program objectives. IV. Require the director of the division of finance, in consultation with the commissioner of administrative services and the state treasurer, to provide for a system of accounts and reports which will insure the integrity and lawful use of all revenues collected by the department, the use of which is restricted by state or federal law. V. Adopt rules, under RSA 541-A, necessary to assure the continuation or granting of federal funds or other assistance not otherwise provided for by law. VI. Approve rates for and regulate every corporation, company, association, joint stock association, partnership and person, their lessees, trustees or receivers appointed by any court, except municipal corporations operating within their corporate limits, owning or operating any toll bridge or toll road.