(a) General rule.--Whenever any highway has been divided into two or more roadways by leaving an intervening space, physical barrier or clearly indicated dividing section so constructed as to impede vehicular traffic, every vehicle shall be driven only upon the right-hand roadway unless directed or permitted to use another roadway by official traffic-control devices, police officers or appropriately attired persons authorized to direct, control or regulate traffic. No vehicle shall be driven over, across or within any such dividing space, barrier or section except through an opening in the physical barrier or dividing section or space or at a crossover or intersection as established.
(b) Traffic-control devices regulating turns.--Whenever necessary for the protection and safety of traffic, official traffic-control devices may be installed at an opening in the physical barrier or dividing section or space or at a crossover or intersection prohibiting or regulating a turn or turns as may be necessary pursuant to the authority of this title.