Va. Code § 46.2-1130
No vehicle shall cross any bridge or culvert in the Commonwealth if the gross weight of such vehicle is greater than the amount posted for the bridge or culvert as its carrying capacity.
Signs stating the carrying capacity shall be erected and maintained near each end of the bridge or culvert on the approaches to such bridge or culvert. Whenever the weight capacity of any structure on the interstate or primary system is reduced below the weight limit permitted on the road of which it is a part, a sign indicating that there is a restricted structure shall be placed in advance of the last alternate route on the road upon which there is a restricted structure. Whenever the weight capacity of any structure is reduced below the weight limit permitted on the road of which it is a part, a sign indicating that there is a restricted structure, shall be placed in advance of the last alternate route on the road upon which there is a restricted structure.
Va. Code § 46.2-1130