RSA 228:21 Powers.

I. The commissioner shall exercise general supervision, control and direction, on behalf of the state, over all matters pertaining to the location, route, alteration, construction, reconstruction, maintenance and discontinuance of highways constructed or maintained wholly or in part by money appropriated from the state treasury, including:
(a) The method and type of construction and kind and quality of materials to be used;
(b) The manner in which such highways shall be maintained;
(c) The designation of certain portions of such highways for one-way traffic, upon which vehicles shall proceed in one direction only;
(d) The designation of certain portions of such highways from which trucks in excess of a gross weight of 12,000 pounds or hazardous materials as d