"How does the City determine speed limits?"

The process of setting speed limits follows the legal requirements of the California Vehicle Code and involves the following steps:

  1. Data Collection: Staff collects speed data from 100 vehicles using radar or laser equipment during free-flowing traffic conditions, avoiding congested peak periods.
  2. 85th Percentile Speed: The speed data determines the 85th percentile speed, which is the speed at or below which 85% of vehicles are traveling.
  3. Review Collision History and Other Factors: Staff reviews recent collision history and considers additional factors permitted under the California Vehicle Code.
  4. Speed Survey Documentation: The findings and recommendations are compiled into a formal speed survey, signed and stamped by a licensed professional engineer.
  5. Posting Speed Limit Signs: Based on the survey’s findings, appropriate speed limit signs are installed.
Speed Limit Sign
In practice, motorists influence the speed limits on road segments through their typical driving behavior. The speed limit for any segment of road is set at the nearest 5 mph increment of the 85th percentile speed of the speed survey. View the Caltrans Manual For Setting Speed Limits to learn more about this process.
 
After the appropriate signs are installed, the police department can legally enforce the posted speed limits with the use of radar. If no physical changes occur on the roadway, the speed survey is considered valid for a period of 7 years and can be extended up to 10 years if conditions remain constant. The speed survey process is repeated every 7-10 years for all City streets except residential/local streets which meet the 25 MPH prima-facie speed.

 

 

See the Traffic Data Map to view the established speed zones in the city.