(a) When the weight limit on a highway or bridge has been adjusted by the Secretary of Transportation, the selectboard of a town, the trustees of an incorporated village, or the city council of a city, as to the legal load limit, then the Secretary, selectboard, trustees, or city council shall have each restricted highway or bridge posted for the legal load limit permitted. The notices shall be of a permanent nature and shall be placed at each end of each restricted highway in each town, village, or city affected or on the approaches to each restricted bridge. The notices shall state the legal load limit permitted to be operated over the highway or bridge.
(b) The notices specified in subsection (a) of this section may be omitted when the restricted highway is a class 4 town highway or a class 3 town highway serving only one residence.