Research On Traffic Signal Control Methods Under Oversaturated Conditions For Urban Trunk Road

With the development of urbanization, traffic congestion in cities becomes increasingly acute. However, the wide range of traffic congestion is due to the block of a single supersaturated intersection. And the intersections in urban trunk road are neck of the road network, its traffic capacity is the key to the whole urban transport properties. Therefore a method to control traffic signals is dying to be found to prevent the worsening of traffic jam and reduce the time that vehicle delay on intersection. For the reason that, a method of traffic signal control based on fuzzy logic theory is put forward to relieve traffic congestion by means of theory analysis of oversaturation and overflow phenomena, verifing its effect.First of all, the traffic state at intersection is classified quantitatively, and a basic understanding about oversaturation and overflow phenomena and the causes of their own are analyzed in the thesis. The vehicle queen length under the control of intersection signal is studied via traffic flow and traffic wave. The thesis also studies the recognition of oversaturation and overflow phenomena.In the second place, the thesis gives accounts of the classification of methods of traffic signal control and signal timing parameter. The idea of fuzzy control at intersection is proposed by studying application of the present traffic control mode and fuzzy control theory. The paper also introduces the traffic simulation tool TransModeler and MATLAB, which are used in signal control.At last, in order to reduce the delay at intersections and prevent the worsening of transportation, fuzzy controllers for green lights demand and delay time are designed by setting queue length and waiting time for red lights as input to dynamically control the signal at intersections. Aiming for dissipating and preventing queuing vehicle at overflow section, the fuzzy controller for phase difference at neighboring intersections is optimized to make the traffic signal control at intersections in overflow come true. The result shows that the method this thesis proposed is superior to Timing time control under the same conditions by computer simulation.