California Code, Streets and Highways Code - SHC § 680

Whenever a franchise is granted by any county or city in any public highway which has been or is subsequently constituted a state highway, the department may enforce any obligations of the grantee or holder of the franchise with respect to the repair of the highway. The department may require any person who has placed and maintained any pole, pole line, pipe, pipeline, conduit, street railroad tracks, or other structures or facilities upon any state highway, whether under that or any franchise, to move it at his or her own cost and expense to such different location in the highway as is specified in a written demand of the department, whenever necessary to insure the safety of the traveling public or to permit the improvement of the highway. However, no such change of location shall be required for a temporary purpose. The department shall specify in the demand a reasonable time within which the work of relocation shall be commenced and the grantee or owner shall commence the relocation within the time specified in the demand and thereafter diligently prosecute it to completion.

In case the owner fails to comply with any such demand, the encroachments specified in the demand become subject to Article 3 (commencing with Section 720), except that no further notice is required.