Simulation-based evaluation for urban expressway ramp metering: a Madison Beltline case

The aim of this paper is to evaluate the effectiveness of the ramp metering on the Madison Beltline, highway section from Park St. to Gammon Rd. The overall network performance was evaluated under “with” and “without” ramp metering conditions by CORSIM (CORridor SIMulation). Three evaluation plans were developed. The first plan is to use speed profile of both mainline and ramps on Beltline freeway with or without ramp metering situations. The second is to evaluate ramp metering with an incident taken place The third to evaluate the effectiveness with service patrol implemented. The results show that travel speed, with metering, increases up to 10% (AM) and 8% (PM) on the westbound and 0.2% (AM) and 0.7% (PM) on the eastbound Beltline, respectively. Most notably, the travel speed between Fish Hatchery Rd. and Midvale Rd. in the westbound direction is increased by 16% (AM) and 39% (PM) respectively. While the speed of mainline increased the speed of ramp of whole sections has been decreased by 16% AM and 18% PM (westbound), and 7% AM and 3% PM (eastbound) respectively. The ramp speed with ramp metering is reduced by 50% compared to that of without ramp metering. In incident case with ramp metering, the speed was higher (17% AM, 7% PM) than that of without ramp metering. With both ramp metering and service patrol implemented, the speed has been greatly increased up to 19% (AM) 1.6% (PM), respectively. This implies that the effectiveness of service patrol is synergistically enhanced with ramp meter ing implementation. In conclusion, the ramp metering on the Madison Beltline gives a positive impact on the travel speed of Beltline and thereby reduces traffic congestion more or less.