Cal. Veh. Code § 21113

(a)
1. (1) Except as provided in paragraph (2), a person shall not drive a vehicle or animal, or stop, park, or leave standing a vehicle or animal, whether attended or unattended, upon the driveways, paths, parking facilities, or the grounds of any of the following:
  1. (A) A public school, state university, state college, or an educational institution exempted, in whole or in part, from taxation.
  2. (B) A unit of the state park system.
  3. (C) A county park.
  4. (D) A municipal airport.
  5. (E) A rapid transit district, transit development board, transit district, public transportation agency, county transportation commission created pursuant to Section 130050 of the Public Utilities Code, or a joint powers agency operating or managing a commuter rail system.
  6. (F) Any property under the direct control of the legislative body of a municipality.
  7. (G) A state, county, or hospital district institution or building.
  8. (H) Any harbor improvement district or harbor district formed pursuant to Part 2 (commencing with Section 5800) or Part 3 (commencing with Section 6000) of Division 8 of the Harbors and Navigation Code.
  9. (I) A district organized pursuant to Part 3 (commencing with Section 27000) of Division 16 of the Streets and Highways Code.
  10. (J) State grounds served by the Department of the California Highway Patrol.
  11. (K) Any property under the possession or control of a housing authority formed pursuant to Article 2 (commencing with Section 34240) of Chapter 1 of Part 2 of Division 24 of the Health and Safety Code.
2. (2) The activities described in paragraph (1) may be performed with the permission of, and upon and subject to any condition or regulation that may be imposed by, the legislative body of the municipality, or the governing board or officer of the public school, state university, state college, county park, municipal airport, rapid transit district, transit development board, transit district, public transportation agency, county transportation commission, joint powers agency operating or managing a commuter rail system, or state, county, or hospital district institution or building, or educational institution, or harbor district, or a district organized pursuant to Part 3 (commencing with Section 27000) of Division 16 of the Streets and Highways Code, or housing authority, or the Director of Parks and Recreation regarding units of the state park system or the state agency with jurisdiction over the grounds served by the Department of the California Highway Patrol.
(b) A governing board, legislative body, or officer shall erect or place appropriate signs giving notice of any special conditions or regulations that are imposed under this section and the governing board, legislative body, or officer shall also prepare and keep available at the principal administrative office of the governing board, legislative body, or officer, for examination by all interested persons, a written statement of all those special conditions and regulations adopted pursuant to this section.
(c) When a governing board, legislative body, or officer permits public traffic upon the driveways, paths, parking facilities, or grounds under their control then, except for those conditions imposed or regulations enacted by the governing board, legislative body, or officer applicable to the traffic, all the provisions of this code relating to traffic upon the highways shall be applicable to the traffic upon the driveways, paths, parking facilities, or grounds.
(d) A public transportation agency that imposes any condition or regulation upon a person who parks or leaves standing a vehicle, pursuant to subdivision (a), is authorized to do either of the following:
1. (1) Enforce that condition or regulation in the manner provided in Article 3 (commencing with Section 40200) of Chapter 1 of Division 17 of this code. The public transportation agency shall be considered the issuing agency for that purpose.
2. (2) Designate regularly employed and salaried employees, who are engaged in directing traffic or enforcing parking laws and regulations, for the purpose of removing any vehicle in the same manner as a city, county, or jurisdiction of a state agency pursuant to Chapter 10 (commencing with Section 22650) of Division 11 of this code.
(e) With respect to the permitted use of vehicles or animals on property under the direct control of the legislative body of a municipality, no change in the use of vehicles or animals on the property, that had been permitted on January 1, 1976, shall be effective unless and until the legislative body, at a meeting open to the general public, determines that the use of vehicles or animals on the property should be prohibited or regulated.
(f) A transit development board may adopt ordinances, rules, or regulations to restrict, or specify the conditions for, the use of bicycles, motorized bicycles, electric bicycles, skateboards, electrically motorized boards, and roller skates on property under the control of, or any portion of property used by, the board.
(g) A public agency, including, but not limited to, the Regents of the University of California and the Trustees of the California State University, may adopt rules or regulations to restrict, or specify the conditions for, the use of bicycles, motorized bicycles, electric bicycles, skateboards, electrically motorized boards, and roller skates on public property under the jurisdiction of that agency.
(h) “Housing authority,” for the purposes of this section, means a housing authority located within a county with a population of over 6,000,000 people, and any other housing authority that complies with the requirements of this section.
(i) “Public transportation agency,” for purposes of this section, means a public agency that provides public transportation as defined in paragraph (1) of subdivision (f) of Section 1 of Article XIX A of the California Constitution or a county transportation commission created pursuant to Section 130050 of the Public Utilities Code.