Evaluation of Coordinated Ramp Metering (CRM) Systems in California

Freeway on-ramp metering has been extensively used as a traffic control strategy to regulate the entry of the on-ramp vehicles to prevent congestion at the freeway merging areas and preserve the freeway capacity. The report presents the research performed and findings on the evaluation of coordinated ramp metering (CRM) systems recently implemented on I-80 Smart Corridor in Caltrans District 4 and SR-99 in Caltrans District 3. The evaluation of CRM on the selected corridors based on “before” and “after” field data during the peak periods showed a 3-9% delay reduction, and 18-28% travel time reliability improvement. Recommendations are provided for implementation of CRM systems.