California Code, Vehicle Code - VEH § 21101.4

(1) The local authority finds and determines that, based upon the recommendation of the police department or, in the case of a highway in an unincorporated area, on the joint recommendation of the sheriff's department and the Department of the California Highway Patrol, one of the following concerns exists along the portion of highway recommended for closure:

(2) The highway is not designated as a through highway or arterial street, or, if the highway is so designated, the local authority, in conjunction with law enforcement and traffic engineers, has determined that a temporary closure may be accomplished without significant impact on the normal flow of traffic.

(3) Vehicular or pedestrian traffic on the highway contributes to the concern described in paragraph (1).

(4) The closure will not substantially adversely affect traffic flow, safety on the adjacent streets or in the surrounding neighborhoods, the operation of emergency vehicles, the performance of municipal or public utility services, or the delivery of freight by commercial vehicles in the area of the highway proposed to be temporarily closed.

(1) Continuation of the temporary closure will assist in preventing the occurrence or reoccurrence of the concern described in paragraph (1), found to exist when the immediately preceding temporary closure was authorized.  This finding and determination shall be based upon the recommendation of the police department or, in the case of a highway in an unincorporated area, on the joint recommendation of the sheriff's department and the Department of the California Highway Patrol.

(2) The highway is not designated as a through highway or arterial street, or, if the highway is so designated, the local authority, in conjunction with law enforcement and traffic engineers, has determined that the immediately preceding temporary closure has been accomplished without significant impact on the normal flow of traffic.

(3) Vehicular or pedestrian traffic on the highway contributes to the concern described in paragraph (1).

(4) The immediately preceding closure has not substantially adversely affected traffic flow, safety on the adjacent streets or in the surrounding neighborhoods, the operation of emergency vehicles, the performance of municipal or public utility services, or the delivery of freight by commercial vehicles in the area of the highway that was temporarily closed.