RHODES-ITMS corridor control project. Final report, September 1996--May 1999

The RHODES-ITMS Corridor Control project addresses real-time control of ramp meters of a freeway segment, with consideration of the traffic volumes entering and leaving the freeway from/to arterials, and the regulation of these volumes via real-time setting of ramp metering rates. Current approaches to traffic-responsive control of ramp meters include (1) time-of day control, (2) locally responsive strategies and (3) area-wide linear programming based approaches are both real-time responsive to traffic conditions and consider the multiple objectives of minimizing freeway travel times and decreasing congestion/queues at the interchanges. A control system, MILOS (Multi-objective Integrated Large-scale Optimized ramp metering System), was developed that determines ramp metering rates based on observed traffic on the freeway and its interchange arterials. MILOS temporally and spatially decomposes the ramp-metering control problem into three hierarchical subproblems: (1) monitoring and detection of traffic anomalies (to schedule optimizations at the lower levels of the control hierarchy), (2) optimization to obtain area-wide coordinated metering rates, and (3) real-time regulation of metering rates to adjust for local conditions. Simulation experiments were performed to evaluate the MILOS hierarchical system.