Heuristic Method for Optimal Diversion Control in Freeway Corridors

Abstract

An integrated control model and a heuristic algorithm for optimal diversion control in commuting corridors are presented. The proposed optimal control integrates ramp metering, intersection signal timing, and off-ramp diversion in an on-line environment that can minimize the total travel time of time-varying demand in nonrecurrent congestion. To reliably capture the flow interactions during freeway incidents, the proposed control model embodies the following three unique features: ( a) modeling traffic state evolution on surface streets with flow conservation within sections, flow transition between sections, and flow discharge at downstream intersections; ( b) estimating time-dependent model parameters adaptively with real-time traffic measurements, instead of assuming they are predetermined, as in most studies; and ( c) having an efficient solution algorithm. Preliminary numerical tests have demonstrated that both the proposed model and algorithm have the potential for use in on-line diversion control in commuting traffic corridors.