The Analysis Of Traffic States Based On The Macroscopic Model

Transportation is the product of economy under the background of great development, and the traffic problem is the result of contradiction of traffic and economic, it has certain hysteresis. The traffic administrative department or the researchers tend to focus only on partly blocking point or area, and what the traffic knowledge they apply is confined to the model describing the movement of vehicles on the road, but now the characteristics of the traffic congestion has changed, gradually from the point congestion, line congestion evolve to the regional road network congestion, and people have no awareness of the inherent law of regional traffic network, the traffic problem is often take temporary solution not effect a permanent cure.The macroscopic traffic organization optimization is the root of all the traffic problems,it optimizes the urban transportation system from the aspects of land use, network structure, transportation way and so on.So this paper presents a traffic state analysis based on macro model, combined with big data era background with huge amounts of data to fast calibration macroscopic model parameters, and verify the accuracy and applicability of the macro model, stretch the experiment of single intersection or a single section just rely on the traditional simulation software to the regionalization.This paper takes macro model as the basis for the traffic state analysis, and mainly has following two achievements:Firstly, this paper puts forward the data treatment method using taxi GPS data derived two-fluid model curve, then the study area was divided into small areas, use the discrete degree ofthe two-fluid curve of all village to determine the difference of each district traffic state, and set up a method that usethe two-fluid model to calculate travel time OD matrix, by analyzing the change of the travel time T under different stopped time Ts, we can analyze the sensitivity and vulnerability of each zone, and provide the basis for the route guidance under different traffic conditions. Take the road network of Changsha for instance, we use matrix iterative method to find out the shortest path between any two communities under the certain stopped time Ts.Secondly, this paper puts forward a method which can derive the MFD and the GMFD using intersection traffic data and taxi GPS data. Through the analysis of the GMFD of the network consisting of 13 intersections of Changsha city center, we found that the uneven distribution of density is one of the causes for capacity reduction. We are able to known the critical average vehicle number of each section and each small network(reflect the ability and capacity of storage space) and capacity through a detailed analysis of the MFD of each section and each small network, by comparing the average vehicle number of current network and the value we can realize network shunt or route guidance, and provide the basis for optimization of traffic management measures.The analysis of regional transport network this paper proposed, can obtain the traffic conditions with less number of conventional traffic index, so as to improve the management efficiency and effectiveness of the transport sector, finally it proves this paper has great application value.