Modeling and integrated control of macroscopic heterogeneous traffic flow in large scale urban network using coloured Petri net

Abstract

The evaluation of perimeter control using Macroscopic Fundamental Diagram (MFD) concept is strongly related with the quality of the corresponding dynamic models. For capturing the real characteristics of traffic dynamics, an enhanced accumulation-based traffic model is proposed in which transfer flow, boundary queues and travel delay are considered simultaneously using coloured Petri net. Taking the advantage of graphical structure, the gated links and junctions on the border of the protected network are modeled as so-called buffers. A simple case study demonstrates the implementation mechanism of this proposed model and its capability of evaluating network performance. Moreover, a perimeter control framework integrated with route guidance is proposed for enhancing the ability of perimeter control on alleviating total travel delay out of the protected network. There are mainly three modules in this integrated framework. Firstly, perimeter control inputs are optimized by the method of model predictive control at regional level. Secondly, a set of internal flow controllers are adopted to homogenize traffic density among subregions and route guidance strategies are used by monitoring the number of queuing vehicles in buffers. Finally, the proposed traffic model is served as a plant for evaluating network performances objectively. The numerical results clearly demonstrate the effectiveness of our proposed integrated control framework in the case of uneven high demand.