FREQ Simulation and Ramp Meter/HOV Bypass Optimization for the Northwest Study Area

The I-290 / Illinois Route 53 corridor in the west and northwest suburban areas of Chicago suffers from heavy congestion throughout and beyond peak travel periods. Traffic management strategies, particularly ramp access strategies prioritizing high occupancy vehicle (HOV) travel, have been recommended as a means of mitigating and even reducing congestion in this corridor. The FREQ model developed by the University of California, in part assisted by the VISSIM modeling tool for bottleneck calibration, was used to determine the effect of implementing HOV priority strategies on entry ramps along the I-290 / IL 53 corridor. FREQ model inputs were based on available historical and forecasted traffic data and network parameters. Several ramp meter and ramp HOV priority bypass scenarios were tested to determine potential year 2030 improvements in several performance measures from the forecasted 2030 base conditions. Findings derived from application of these various scenarios indicated net reductions from 2030 base in: passenger-hours of travel (PHT) ranging from 2.0% to 15.4%, and tons of volatile organic compounds (VOCs) emitted from 2.4% to 13.5%. Vehicle-miles traveled (VMT) and gallons of fuel consumed remain relatively constant across scenarios. In addition to the results of the FREQ analysis, present-day expressway and arterial highway design characteristics that adversely impact vehicle capacity and queue storage capability of ramps are identified and explained.