Research On Method Of Coordinated On-ramp Metering In Urban Expressway

With the development of society and economy, traffic jam has become increasingly serious problem. Especially in big cities, the road capacity has been unable to meet the growing traffic demand. As a fast, comfortable and safe approach, urban expressway played an important role in relieving this problem at a certain extent, but simply constructing more roads can't solve the problem of traffic jams.On-ramp metering is one of the most direct and efficient methods to avoid traffic jams in expressway. The essence of on-ramp metering is to restrict the access traffic volume to avoid the traffic demand exceeding the capacity. The ideal goal is to produce and maintain a fluent and non-blocking traffic flow in the expressway. Dynamic OD matrix which describes variable traffic demand is a basic parameter to accurate predict the traffic conditions and provide efficiently traffic control. The accurate prediction of the OD matrix is the premise of ramp metering. This dissertation inputs the OD matrix calculated from traffic volume as a parameter of on-ramp metering And through the analysis of various typical methods of ramp metering in expressway, the dissertation proposes a ramp metering method based on optimal coordination and control, and make the maximum"kinetic energy"as the main objective function to obtain optimal traffic service volume in the express way. Finally, Matlab is used in examples to accomplish the simulation and evaluation, and the result proves that the method used in this dissertation has good control effect.