Linear Quadratic MPC for Integrated Route Guidance and Ramp Metering

Abstract

Capacity drop is a common phenomenon that typically occurs at the downstream of freeway congestion area, which decreases traffic operation efficiency significantly. It can be avoided by some traffic control measures such as ramp metering. In this paper, a generic first-order traffic flow model is proposed, to reproduce the capacity drop at both on-ramp bottleneck and lane drop bottleneck. Based on this model, a linear quadratic model predictive control strategy for the integration of dynamic route guidance and ramp metering is presented. The objective is to minimize the total time spend of a traffic network. Due to the linearity of the optimization problem, the problem can be solved efficiently, which makes the problem suitable for real-time traffic control. A hypothetical traffic network containing both on-ramp bottleneck and lane drop bottleneck is utilized as a test bed, to demonstrate the effectiveness of the proposed control strategy.