Simulated Coordinated Ramp Metering Study in Utah Found It Effective in Reducing Mainline Vehicle Delay by 4.74 Percent, Compared to Fixed Ramp Metering.
Microsimulation Study Analyzed Five On-Ramps Along an 11-Mile Corridor on I-15 in Utah to Assess Mobility Benefits from Coordinated Ramp Metering.
Utah, United States
Design and Evaluate Coordinated Ramp Metering Strategies for Utah Freeways
Summary Information
Ramp metering is widely used as an effective freeway operation management strategy to reduce overall freeway congestion by regulating the amount of traffic entering the freeway. This study deployed coordinated ramp metering systems in a simulation and evaluated the operational performance of deployed systems, which integrated several upstream ramp meters to decrease one or several downstream bottlenecks in Utah. Five on-ramps were selected for this study along the 11-mile-long corridor of northbound I-15 from Bangerter to 7200 S. This study used real world traffic count data collected in October of every year from 2017 to 2020.
METHODOLOGY
The study utilized the existing Utah DOT datasets to identify freeway bottlenecks and identified selected locations that could benefit from the coordinated ramp metering. A microsimulation model was developed for the chosen corridor and calibrated with real-world traffic flow data. This calibrated model was subsequently used to simulate and assess the operational and safety impacts of the coordinated ramp metering strategy under various levels of freeway mainline congestion. A comparative analysis was conducted for fixed and coordinated ramp metering strategies.
FINDINGS
The results showed an average reduction in mainline vehicle delay by 4.74 percent, comparing the fixed versus the coordinated ramp metering strategies.
It should be noted that the overall delay reduction from coordinated ramp control was offset somewhat by an increase in associated ramp delays, considering the average of the five on-ramps used in this study. Three of the five on-ramps experienced reduced vehicle delay and queue length, while the other two saw significant increases. This was attributed to the fact that a reduced metering rate was required to relieve mainline congestion, so more vehicles were stored on on-ramps. Although the on-ramp delay increased, the queue does not spill over to the local street.
