S.C. Code Ann. § 57-13-90: Width of bridges on state highways.

It shall be unlawful for any person, board, commission or other group of persons charged with the duty of building bridges on the public highways of this State within the State highway system to construct any bridge of insufficient width to allow the free passage of at least two vehicles at one time, and it shall also be unlawful to construct any such bridge without providing for and maintaining a clearly defined center line on it, sufficiently clear and distinct to be plainly discernible at all times. On all such bridges there shall be provided ample width on each side of such line for the passage of one vehicle.