Simulation And Empirical Studies Of Traffc Flow

Transport system is very important to the economic life. With rapid economic develop-ment, modern traffc is facing a number of serious problem. If only spend on the constructionof roads hardware facilities to solve traffc problems, the effect will be very limited. There-fore, we need to study theory, and fundamentally solve the traffc problem. At present,people have already begun the studies of traffc ffow theory. Especially in the Road TraffcFlow Modeling, it has made a lot of achievements. this paper outlines some achievements ofprevious in road traffc ffow models in chapter 1. And base on the achievements of formerpeople, some other works have been done.1,As the preparatory work, chapter 2 will more detailedly analysis of parameters asffow, speed, occupancy, time headways and lane-change frequency for microscopic model oftraffc ffow, and propose some more feasible methods for measurement and calculation. Inaddition, a new concept of ffow have been proposed to the occupancy, named volume ffow.This concept is very important to the studies of cellular automata traffc models.2,By segmentation of NaSch model we found that NaSch model can only work underthe situation that time step is same to the minimum time headways. If timeways is less thanone second, NaSch model does not exist the problem of Small ffow. Under the situation thattime step is not same to the minimum time headways, we proposed a parameter k to improvethe model. NaSch model after improved can be successfully applied to various segmentation,and show a lot of traffc characteristics which original model can not show, such as brakingprocess and the distribution of time headways. In addition, through the combination of thesegmentation and the concept of volume ffow, this chapter discussed the equivalent of thevehicles lengthening with the shortening of the time headways.3,In chapter 4, we proposed a cellular automaton model of two-lane on the two-dimensional grid. Introduced the normal distribution of the maximum speed, and comparedasymmetrical lane-change rules with symmetrical lane-change rules. By comparison knowsthat, for the linear decline of the speed in the free ffow phases, the normal distributionmaximum speed play a decisive role. In the free ffow phases, symmetric and asymmetricrules are all effective, At the same time, the asymmetric rule(right-lane preference) is moreeffective than symmetric rule. For the lane-change process, the normal lane-change will notaffect the ffow. But the ffow will be seriously affected when time is too long. 4,To characteristics of Chinese traffc ffow, a preliminary study of simulation to thetraffc ffow mixing by cars,motorcycles and bicycles has been proposed. By compared withthe measured data we found that, if neglected the role of o-Road vehicles, the simulationresults will be large deviations. Then we introduced a coeffcient H to simulate the role ofthe vehicles on o-Road. It takes effect.Finally, this article prospects the future study of the traffc ffow.