Coordinated Control Strategy Of Expressway On-ramp And Variable Speed Limit

As an important part of urban transportation system, the related questions of expressway have been widely concerned. Urban expressway traffic flow is complex, nonlinear, discrete and time-varying, so the questions of expressway traffic control also face great challenges.Although more and more scholars have pay attention to this field, most of the related research have many defects, such as the relatively low accuracy, the single optimization, and the unsatisfied control effect.Because of this reason, this paper studied the problems of expressway traffic coordination control, and did some related discussions of improved macroscopic traffic flow model, the related model and algorithm of the objective function, and several aspects, such as test samples.This article improved the deficiencies of original model which was based on the macroscopic traffic flow model MetaNet, such as introducing speed density sensitive coefficient and ramp metering model considering the influences of the pilot acceptable gap, etc. And based on this, the entrance ramp control and variable speed-limit control of expressway traffic flow was studied, and the improved expressway MetaNet model under the influence of their respective was established, and then from the perspective of the main line, the entrance ramp control and variable speed feedback coordinated control of traffic flow model was established.On the basis of the improved MetaNet model, the improved MetaNet model based on traffic and environmental benefits was established from the perspective of two aspects of the traffic and environmental benefits, such as the complement of travel time spend, as a result, the traffic efficiency model was established. In addition, the CMEM model is introduced, and then the improved MetaNet model and CMEM model are fused. It is the objective function of the subsequent optimal control, and it is also the basis of the entrance ramp-variable speed-limit control strategy which is based on the MPC.This paper discussed the related questions of the MPC control, such as controlling parameters, calculation process and the optimization algorithm. The improved MetaNet model and the characteristics of the objective function was proposed in this paper. This paper introduced the method of solving multi-objective optimization problems of hierarchical sequence method based on particle swarm algorithm, and the algorithm process was presented. Moreover, the work for subsequent research was done, such as the classification of the algorithm level, and the confirmation of the toleration.This paper carried out the inspection and discussion of the whole control strategy based on the measured sections of data, and the improved MetaNet model was compared with the classic GreenSheilds model. From the result we can know, the improved MetaNet model which is establishedin this paper could accurately describe the traffic flow. At the same time, this paper introduced the single entrance ramp control and single variable speed control, the result of being compared with the coordination control and the actual situation showed that the established control policy effect was good.In addition, this article also did some sensitivity analysis to some of the initial model parameters, and on this basis, the expressway control countermeasures were given, it can be the reference for technicians in the actual operation.