Study on Traffic-Responsive Metering Algorithm in Baltimore Estimated 3.6 and 8.8 Percent Reduction in Average Travel Time for Trucks and Cars, Respectively, With Local Signal Synchronization.

METHODOLOGY

In this study, an open-source mesoscopic traffic network simulation tool was used. The model network was calibrated for the morning peak period using multi-source multi-class traffic data, including passenger car and truck counts at 153 loop detector sites and 15-minute average speeds on 537 links. The calibrated model was used to examine two different control strategies, ALINEA and Local Signal Synchronization (LSC), at two selected locations on the I-70 corridor in Maryland. ALINEA was a traffic-responsive metering algorithm which tracks the difference between desired downstream occupancy and current occupancy with ramp metering rate. LSC managed queues at critical locations by coordinating neighboring intersection traffic signals and freeway on-ramp meters, wherever available. Three scenarios were tested to assess ramp metering impact at locations A and B: (1) Baseline: no ramp metering control, (2) ALINEA control, and (3) LSC control. The aggregated traffic metrics within the local roads around the controlled ramp and downstream roads were used for evaluation, including vehicle hours traveled (VHT), vehicle miles traveled (VMT), average travel time, average travel distance and average vehicle delay.

FINDINGS

For location A:

• LSC reduced average travel times for trucks and cars by 3.6 and 8.8 percent, respectively, when compared to the baseline.
• ALINEA reduced average travel times for trucks and cars by 2.2 and 5.3 percent, respectively, when compared to the baseline.
• LSC reduced VHT by 14.7 percent compared to the baseline when both vehicle types were combined.
• ALINEA reduced VHT by 8.9 percent compared to the baseline when both vehicle types were combined.
• The results showed that both control strategies effectively reduced fuel use for cars, ranging from 6.1 to 10.9 percent. 

For Location B:

• The results showed reductions of 7.1 and 4.9 percent in average travel times for trucks and cars, respectively, with LSC when compared to baseline. ALINEA resulted in reductions of 3.1 and 1.2 percent for trucks and cars, respectively.
• LSC reduced VHT by 11.4 percent for all vehicle types.
• LSC could reduce fuel consumption by 7.2 and 6.5 percent for trucks and cars, respectively.