Vehicles: speed limits: downward speed zoning.

(1) Existing law requires the Department of Transportation, after consultation with local agencies and public hearings, to adopt rules and regulations prescribing uniform standards and specifications for all official traffic control devices and setting of speed limits. Existing law makes it a crime for a driver to fail to obey a sign or signal, defined as regulatory in the California Manual on Uniform Traffic Control Devices (Manual) , or a Department of Transportation-approved supplement to that manual. This bill would require the Department of Transportation to revise the Manual, as it read on January 1, 2012, to require the department or a local authority to round speed limits to within 5 miles per hour of the 85th-percentile speed of free-flowing traffic. The bill would allow, in cases in which the speed limit needs to be rounded up to the nearest 5 miles per hour increment of the 85th-percentile speed, the department or a local authority to decide to instead round down the speed limit to the lower 5 miles per hour increment, but then the department or a local authority would be prohibited from reducing the speed limit any further for any reason. (2) This bill would incorporate changes to Section 21400 of the Vehicle Code proposed by both this bill and AB 345, which would become operative only if both bills are enacted and become effective on or before January 1, 2012, and this bill is chaptered last.