Regional hierarchical optimization control method based on critical region and boundary flow control

The macroscopic fundamental diagram (MFD) is put in place to characterize the traffic characteristics of the road network for addressing the problem of area traffic congestion in the road network caused by the uneven distribution of traffic flow. A critical region identification model is constructed to identify key control areas. A set of regional traffic signal classification optimization control strategies, steps, and models are proposed based on the boundary flow control model. First, the road network is divided into three-level areas according to the critical region, namely, core, buffer, and peripheral sub-regions, to obtain two boundaries. Second, the calculation model of MFD critical value, regional aggregate traffic flow control amount, inter-region driving rate difference, and boundary optimization traffic flow difference is constructed with simulation modeling and mathematical methods. Third, regional hierarchical optimization control strategy and model are implemented to assess and feedback traffic state of each sub-region until all sub-regions reach a non-congested state. In addition, the regional hierarchical optimization control method is applied and analyzed in the experimental road network of the central district in Hefei City, China. Results demonstrate that the proposed method has superior operability and can quickly balance regional traffic flow and effectively reduce vehicle delays in congested areas to relieve regional traffic congestion.