A time-dependent lane-based cell transmission model for coordinated signal optimization

Lane markings showing road users the permitted movements on traffic lanes can also be defined as decision variables and optimized together with signal timings in a unified optimization framework for the design of a signal-controlled junction. Traffic demand patterns are time-varying in nature, so it is a challenge to design and operate one reliable set of permitted movements in the form of lane markings showing road users the allowable lane turning directions. The lane-based design concept can be extended for the design of a linked signal-controlled network as the network configuration and signal timings can be optimized simultaneously. The present lane-based model still works in a point-queue modeling system without specific constraints to account for road spatial limits, so vehicle queues can be developed infinitely along road links. More recently, a signalized cell transmission model has been formulated as an optimization module to optimize the reserve capacity and linked signal settings in a traffic network, taking the spatial capacity of road links into consideration. Because of the limited holding capacity of road links, shorter cycle lengths are used to release vehicle queues more frequently to prevent overflow and waste of green times. The junction and network optimization can be integrated to give more reliable designs. In this paper, the lane-based method and signalized cell transmission model are combined in the design optimization framework. A pair of T-junctions connected by short links is modeled as a numerical example to show the effectiveness of the proposed lane-based cell transmission model in a multi-period design.