Modeling And Simulation Of Traffic Flows Considering Different Bend Conditions

Transportation system is the important part of human life and society economic activities, and it’s the indispensable condition for the man’s daily lives, the normal operation of enterprises and the rapid development of economy. Recent years, traffic construction of many cities with the properties of large-scale, compressive strength, and high standard, has improved the traffic situation to some extent, but some traffic problems, like the traffic jam, environmental pollution and traffic accident, have not solved fundamentally. The shortage of systemic researches of the internal and evolutional mechanisms is the main reason which leads to the appearance of these severe traffic problems, all of them increases the strength to solve the difficulties for traffic researchers.Based on the cellular automata (CA) theory, The CA models considering the different bend conditions are proposed according to the true traffic characteristics, then the traffic running situation is simulated through the Matlab program, and the complex properties are also studied. It hopes to provide some scientific basis for traffic practice and planning. This paper’s main contents are as follows:(1)Firstly, the Human-vehicle-environmental characteristics and the combination types of road with various bend structures were analyzed; Secondly, according to these features, on the basis of the NS model, the operation rules of bend were amended and a single-lane CA model was established; Finally, the vehicles operation features were researched using the CA model and the conclusion had got in the condition of different bend length, bend radius length and road friction coefficient.(?)With the increase of bend radius length, the maximum flux will increase, and the longer the radius is, the higher maximum flux is; when the radius becomes shorter, the traffic jam about the bend becomes more severe, and the bend’s blocking effect also becomes more remarkable.(?)In the different length of bend, the complex nonlinear phenomenon traffic waves of alternate running and stopping is all found. Besides, the inhibition effects are also observed in all different bends, but the length of bends has the least influences to the traffic flux;(?)The higher friction coefficient of road is, the weaker "blocking effect" of bend flow in the same bend radius will be, and the less evident "bottleneck effect" of bend. When the friction coefficient is smaller, the results are exactly opposite. When the friction coefficient is greater than0.9, the influence of traffic flow will disappear. (2)In order to simulate the real traffic flow well, A two-lane CA model had been presented, and the traffic operation status using two kinds of various lane-changing rules was also simulated.(?)Under the same conditions of road turning, the flux of active lane-changing rules is less than that of positive ones in general case. At the different ration between the fast vehicles and slow ones, the more slow vehicles occupy the road, the smaller flux we get, and the less slow vehicles, the greater flux.(?)When the radius of bend is less than200meters, the bend will significantly impact on the flux. We obtain that the flux keeps a steady value relatively if the critical density is greater than0.1; if the radius is greater than200meters, the influence of traffic flow will disappear basically.(?)There are some differences between the results of single-lane CA model and the two-lane C A model, which are the traffic jam only occurs on the bend with two-lane model, but it happens in the all road for the other one, and the car-following phenomena only appear in the left lane because the slow vehicles and the fast ones have segregated each other, which is called the segregation phenomena in multi-lane mixed traffic flow.