(a) The weights stated in Sections 56-5-4070, 56-5-4075 and 56-5-4140 are applicable to all roads and bridges as designated except the Grace Memorial Bridge in Charleston County on which trucks of no greater weight than ten tons are allowed.

(b) The Grace Memorial Bridge (U.S. Route 17 over the Cooper River in Charleston County) is not a designated route in accordance with the provisions of the Surface Transportation Assistance Act of 1982 [49 USCS Appx Sections 2301 et seq.]. Vehicles being operated or used on such segment of highway may not exceed a width of ninety-six inches nor exceed the gross weight limit as posted by the Department of Transportation, except during emergency conditions as determined by the Department of Transportation. Vehicle combinations of a truck-tractor, trailer or a truck-tractor, semitrailer or a truck-tractor, semitrailer, trailer or a truck-tractor, trailer-trailer are prohibited from being operated or used on this segment of highway.