Phase 1: Preparations for Field Testing of Combined Variable Speed Advisory and Coordinated Ramp Metering for Freeway Traffic Control

The objective of this project was to prepare for limited field test of a newly developed control algorithm for Coordinated Ramp Metering in the next project.  Extensive site selection was conducted for future testing of the Coordinated Ramp Metering (CRM) algorithm developed in a precious project supported by the FHWA Exploratory Advanced Research (EAR) program.  Two major corridors were analyzed: I-880 between SR237 and Auto Mall Parkway in the Bay Area and SR99 NB between Elk Grove and the intersection with SR50 (about 13 miles long) in Sacramento.  Main factors for site selection included: road geometry, traffic volume, bottleneck locations and traffic situations, traffic data quality, and availability of ramp meter facility.  This project focused on SR99 NB.  PeMS data was used for modeling and model calibration of the two corridors in Aimsun microscopic traffic simulation.  Based on the calibration model, the default field operational Local Adaptive Ramp Metering (LARM) and the Optimal CRM with Queue-Overwrite algorithm has been applied.  Simulation has been conducted for multiple replications.  Preliminary simulation results showed that, on average, Total Travel Time (TTT) of the overall system could be reduced by 8%.  Total Delay (TD) on the mainline could be reduced by 15%.  Total Travel Distance could be increased by 0.5% and Total Number of Stops could be reduced by 2.9%.  The number would depend on traffic volume.  The microscopic simulation results need further fine tuning and field testing at the selected site(s) in the next phase of the project.  


Project Final Report

Final Report