California Code, Streets and Highways Code - SHC § 27177.5

A towing service may be maintained by a bridge and highway district on each vehicular crossing under its jurisdiction, and said district may furnish such towing and emergency road service as is necessary to permit the orderly flow of traffic upon such crossing and upon district property. The district may prescribe and collect reasonable rates for towing and other services furnished. When any vehicle or object on any vehicular crossing or road under district jurisdiction or upon district property upon which towing service is maintained is stopped for any reason and such vehicle or object is obstructing or may obstruct traffic, the district shall order that such vehicle or object be towed by the towing service either to the nearest property of the bridge and highway district designated for the parking or storing of vehicles, or to a suitable parking location on a public street or highway and thereupon left in the custody of the owner or operator of such vehicle or object, or his agent, or, in the event no such owner, operator, or agent is present, or if such owner, operator, or agent so requests, to a public garage or off-street parking facility. The district may prescribe the limits within which the towing service authorized herein shall be operated. The district may furnish and deliver fuel to vehicles, the supply of which is exhausted, or change tires, and may charge a reasonable sum for the services and materials furnished. If the district deems it safe and advisable and the owner or operator of such vehicle or object so requests, it may be towed from the vehicular crossing as herein provided.

The towing service maintained by a district pursuant to this section shall be the only towing service authorized to render service to or remove vehicles or objects which become disabled upon vehicular crossings or property under the jurisdiction of the district.