Weight, load, speed limits may be lowered; condition precedent.

Anything in this chapter to the contrary notwithstanding, the Department of Transportation with respect to state roads, and local authorities with respect to highways under their jurisdiction, may prescribe, by notice hereinafter provided for, loads and weights and speed limits lower than the limits prescribed in this chapter and other laws, whenever in its or their judgment any road or part thereof or any bridge or culvert shall, by reason of its design, deterioration, rain, or other climatic or natural causes be liable to be damaged or destroyed by motor vehicles, trailers, or semitrailers, if the gross weight or speed limit thereof shall exceed the limits prescribed in said notice. The Department of Transportation or local authority may, by like notice, regulate or prohibit, in whole or in part, the operation of any specified class or size of motor vehicles, trailers, or semitrailers on any highways or specified parts thereof under its or their jurisdiction, whenever in its or their judgment, such regulation or prohibition is necessary to provide for the public safety and convenience on the highways, or parts thereof, by reason of traffic density, intensive use thereof by the traveling public, or other reasons of public safety and convenience. The notice or the substance thereof shall be posted at conspicuous places at terminals of all intermediate crossroads and road junctions with the section of highway to which the notice shall apply. After any such notice has been posted, the operation of any motor vehicle or combination contrary to its provisions shall constitute a violation of this chapter. However, no limitation shall be established by any county, municipal, or other local authorities pursuant to the provisions of this section that would interfere with or interrupt traffic as authorized hereunder over state roads, including officially established detours for such highways, including cases where such traffic passes over roads, streets or thoroughfares within the sole jurisdiction of the county, municipal or other local authorities unless such limitations and further restrictions have first been approved by the Department of Transportation. With respect to county roads, except such as are in use as state road detours, the respective county road authorities shall have full power and authority to further limit the weights of vehicles upon bridges and culverts upon such public notice as they deem sufficient, and existing laws applicable thereto shall not be affected by the terms of this chapter.