A.R.S. § 28-729: Laned Roadway Rules

28-729. Driving on roadways laned for traffic

If a roadway is divided into two or more clearly marked lanes for traffic, the following rules in addition to all others consistent with this section apply:

1. Except as provided in sections 28-778 and 28-903, a person shall drive a vehicle as nearly as practicable entirely within a single lane and shall not move the vehicle from that lane until the driver has first ascertained that the movement can be made with safety.

2. On a roadway that is divided into three lanes, a person shall not drive a vehicle in the center lane except when overtaking and passing another vehicle where the roadway is clearly visible and the center lane is clear of traffic within a safe distance, or in preparation for a left turn or where the center lane is at the time allocated exclusively to traffic moving in the direction the vehicle is proceeding and is signposted to give notice of the allocation.

3. Official signs may be erected directing slow-moving traffic to use a designated lane or designating those lanes to be used by traffic moving in a particular direction regardless of the center of the roadway, and drivers of vehicles shall obey the directions of every sign.