EVALUATION OF THE SYSTEM-WIDE EFFECTS OF ONLINE ESTIMATION METHODS ON FEEDBACK-BASED COORDINATED RAMP METERING STRATEGY

The critical density of a freeway link is subject to changes over time owing to such circumstances as environmental conditions (snow, rain, etc.) and traffic incidents. The critical density affects the performance of some ramp metering strategies that make use of it as a threshold value for control action; therefore, it is imperative to trace the real value of the critical density. The focus of this paper is to evaluate the effects of the novel online critical density estimation methods proposed by Ozbay et al. (2006) on the performance of the two new feedback-based coordinated ramp metering strategies, namely C-MIXCROS and D-MIXCROS (Kachroo and Ozbay 2003), which explicitly consider ramp queues using microscopic simulation models on an 11-mile corridor of I-295 in South Jersey under various demand conditions.