Veh. Code, § 21719

(a) Notwithstanding any other law, in the event of an emergency occurring on a roadway that requires the rapid removal of impediments to traffic or the rendering of assistance to a disabled vehicle obstructing a roadway, a tow truck driver who is operating under an agreement with the law enforcement agency responsible for investigating traffic collisions on the roadway, summoned by the owner or operator of a vehicle involved in a collision or that is otherwise disabled on the roadway, or operating pursuant to subdivision (a) of Section 2430.1 may utilize the center median or right shoulder of a roadway if all of the following conditions are met:

(1) A peace officer employed by the investigating law enforcement agency is at the scene of the roadway obstruction and has determined that the obstruction has caused an unnecessary delay to motorists using the roadway.

(2) A peace officer employed by the investigating law enforcement agency has determined that a tow truck can provide emergency roadside assistance by removing the disabled vehicle and gives explicit permission to the tow truck driver allowing the utilization of the center median or right shoulder of the roadway.

(3) The tow truck is not operated on the center median or right shoulder at a speed greater than what is reasonable or prudent having due regard for weather, visibility, the traffic on, and the surface and width of, the roadway, and in no event at a speed that endangers the safety of persons or property.

(4) The tow truck displays flashing amber warning lamps to the front, rear, and both sides while driving in the center median or right shoulder of a roadway pursuant to this section.

(b) For purposes of this section, “utilize the center median” includes making a U-turn across the center median.