A.R.S. § 28-731: Driving on divided highways

If a highway is divided into two roadways by leaving an intervening space or by a physical barrier or clearly indicated dividing section constructed to impede vehicular traffic, a person shall drive a vehicle only on the right-hand roadway and shall not drive a vehicle over, across or within the dividing space, barrier or section, except through an opening in the physical barrier or dividing section or space or at a crossover or intersection established by public authority.