(b) The department of transportation shall cause to be determined, for all bridges and elevated structures under its jurisdiction, the capacity in tons of two thousand pounds which the bridge or structures will safely carry. At bridges or structures of insufficient strength to carry safely the legal loads permissible by section three hundred eighty-five of this chapter, the department of transportation shall cause signs to be erected to inform persons of the safe capacity.

(c) Such department of transportation shall cause signs to be erected to inform persons of the legal overhead clearance for all bridges and elevated structures on highways under its jurisdiction. The legal clearance shall be one foot less than the measured clearance. The measured clearance shall be the minimum height to the bridge or structure measured vertically from the traveled portion of the roadway. On bridges or structures having fourteen feet or more of measured clearance, no such signs shall be required.

(d) The department of transportation may by order, rule or regulation temporarily exclude from any portion of any state highway and any highway and bridge constructed or to be constructed by the state on any indian reservation any vehicle with a gross weight of over four or more tons or any vehicle with a gross weight in excess of any designated weight on any wheel, axle, any number of axles, or per inch width of tire when in its opinion such highway would be materially injured by the operation of any such vehicle thereon. Such exclusion shall take effect upon the erection of signs on the section of highway from which vehicles are excluded, and a notice that such vehicles are excluded shall be published in a newspaper in the county where the highway is situated. The exclusion shall remain in effect until the removal of the signs is directed by the department of transportation.