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Open Access Publications from the University of California

Congestion-Responsive On-Ramp Metering: Recommendations toward a Statewide Policy


The objective of this project was to develop recommendations toward a statewide policy of congestion responsive freeway ramp metering (CRRM) operation. The research has been performed in the following approaches: First an empirical “before” and “after” freeway corridor performance evaluation was performed on a selected set of California’s freeway corridors that had implemented congestion responsive ramp metering. Next, other important policy and operational factors that impact the effectiveness of extended hours ramp metering were evaluated: traffic detector health and data quality and their potential impact on CRRM operation, immediate operation hours, ramp metering (RM) light setting to “Green-Ball” or “Black”, on-ramp storage capacity effects and some alternative solutions to reduce/avoid queue-override, and properly handling institutional relevant issues to gain support from local jurisdictions. The corresponding recommendations are included in this report.

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