Optimal Method Of Signal Parameters Based Of Channelization Length At Signalized Intersections

With the development of Chinese economy, the number of car is increased and the net of city which is full of car become jam. More and more intersections don't satisfy traffic need which the length of channelization doesn't enough to contain cars. This paper does research in the capacity, lane group saturation and signal timing method.This paper does research in the signal timing method of intersection whose channelization is shorter than the length of car's queue and pay much attention on the saturation flow rate of lane group,then analyze the factors of cycle, the second saturation flow rate which have influence on intersection. The content is divided into five chapters, the third chapter and the fourth chapter are important chapters.The first chapter introduces the background of research, the aim of research and the content of research. The theory of single signal timing theory is foundation of signal timing theory, but the all matured signal timing methods use the stable saturation flow rate and do not consider that saturation flow rate will be change when the length of approach is not enough longer. So in order to satisfy signal timing theory, this paper will do research in the signal method when the length of approach is shorter than the length car's queue.The second chapter reviews signal coefficient and theory and analyzes the characteristic of signal theory. At first, this chapter introduces basic signal coefficients and determine their notes. Then this chapter concludes signal theories such as the methods of TRRL, ARRB and HCM which are comprehensively used are using stopping line as the research transect and regard car passing stopping line as passing the intersection. The conflict point method uses the point of conflict as researching transect and pay much attention on conflicts that is aroused by straight flow and left flow. This method is applied in two-signal intersection, but it isn't used by traffic engineer because that its formula is too complicated and its coefficients are hard to be determined. These methods have the same problem that they don't consider how to make signal when the length of channelization is not enough longer to contain cars that come into entrance internal of red light.The third chapter sets up a corresponding saturation flow rate model and modifies Webster model based of corresponding saturation flow rate. On the first place, this chapter introduces the note of saturation flow rate through analyzing the process of releasing cars'flow. Based on saturation flow rate, others coefficient can be computed such as capacity. On the second place, it demonstrates two kind of methods which are used to calculate saturation flow rate. Compared with Webster and others method, cumulative curve method can measure starting time and ending time. But we can only get stable saturation flow rate through all kinds of methods and then get the lane group saturation. These saturation flow rate can not demonstrate the process of car flow correctly. So this paper puts forward corresponding saturation flow rate and set up a model to settle this problem. And Webster method is modified on the base of corresponding saturation flow rate so as to make it satisfy shorter channelization. At last, using the fact interprets the process of method and acquires good result.The fourth chapter analyzes the factors which have effect on capacity such as channelization's length, cycle and the second saturation flow rate and establishes a biggest capacity signal timing model. The first part of this chapter reviews phase capacity model and intersection capacity model. The second part of this chapter summarizes factors which have influence on intersection capacity such as the length of channelization, and give formula of capacity and widing part length. Then the following part set up an example about two-phase intersection and four-phase intersection, from 60-second to 200-second, after an interval of ten seconds, using capacity increasing rate and capacity cumulative increasing rate to illustrate cycle's effect and get conclusion that if cycle is short the increasing capacity rate is small and if cycle is long the creasing capacity rate is big. However, if cycle is over 120 second, capacity increasing rate become small obviously. And this paper analyzes the factor of the second saturation flow rate. On the base of analyzing influence factors, the third part designs a signal model whose motivation is the biggest capacity and use example to illustrate computing process. The result is good.The fifth chapter summarizes the paper and put forward problems which will be researched in the future.