Whenever the legislative body of a city determines that it is necessary for the more efficient maintenance, construction, or repair of streets and roads within the city it may contract with the board of supervisors of any county for the rental, by the city, of such county's equipment for the maintenance, construction, or repair of such streets and roads, or for the maintenance, construction, or repair of such streets and roads by the county.
Ca. Sts. and High. Code § 1803