Traffic safety: speed limits.

Existing law establishes various default speed limits for vehicles upon highways, as specified. Existing law requires the Department of Transportation (Caltrans) , by regulation, to require Caltrans or a local authority to round speed limits up or down to the nearest 5 miles per hour of the 85th percentile of free-flowing traffic. This bill would, if the speed limit needs to be rounded down to the nearest 5 miles per hour increment of the 85th-percentile speed, authorize Caltrans or a local authority to lower the speed limit by 5 miles per hour from the nearest 5 miles per hour of the 85th percentile, as specified. The bill would prohibit the total reduction in the speed limit from exceeding 12.4 miles per hour from the 85th-percentile speed and would authorize a local authority to retain the currently adopted speed limit without further reduction or restore the immediately prior adopted speed limit without further reduction. The bill would make conforming changes. Existing law establishes various speed limits and prohibits a person from driving with a greater speed than those limits. Existing law prohibits a peace officer or other person from using a speed trap in arresting, or participating in the arrest of, any person for any alleged violation of the Vehicle Code, and prohibits the use of a speed trap in securing evidence as to the speed of any vehicle for the purpose of an arrest or prosecution under the Vehicle Code. Existing law defines the term "speed trap," for these purposes, among other things, to include a particular section of a highway with a prima facie speed limit that is provided by the Vehicle Code or by local ordinance, if that prima facie speed limit is not justified by an engineering and traffic survey conducted within a specified number of years of the alleged violation, and enforcement of the speed limit involves the use of radar or any other electronic device. Existing law exempts a local street or road, school zone, senior zone, or business activity district, as defined, from that definition. This bill would also exempt a speed limit adopted by a local authority, as specified, from the definition of "speed trap."