Study On The Closed-loop Control Of Urban Expressway

In recent years, the speed of expressway is also. Many cities are planning their ownExpressway Networks according to the characteristics of the city, the construction ofurban expressway network alleviate the traffic congestion to a certain extent. With therapid growth of traffic demand, urban expressway of many cities appeared “slow”phenomenon.The urban expressway of China is the main object of this thesis. Firstly, itintroduce the two forms of urban expressway in China, With the unbalanced economicdevelopment, the construction of expressway has two forms: One is fully-closed, wholeinterchange, forming a continuous traffic flow of urban expressway; another issemi-closed, forming a discrete flow of urban expressway. Though the contrastiveanalysis of the traffic characteritics between the two kinds urban expressways.This thesis points out the difference of their traffic characteristics, including traffic flow, traffic composition and the vehicle running speed.This thesis put the urban expresswaywhich is discrete flow as the main objiect. Secondly, the main control method is thegreen wave coordinated control for the discrete flow of urban expressway currently,whether is timing control or sensor control, all belong to the open-loop control which isthe lower-level control system, namely: only based on the input (mainly refers to thetraffic) to adjust the signal timing, unable according to the output (mainly refers to thedelay) to adjust signal timing, the main reason is the delay unable be detected in realtime. However, with the recent popularization and application of computer videodetection technology, the real-time detection of delays is possible, which is provide aplatform and opportunity for traffic control in the open-loop to enhance the closed-loop.Therefore, this paper applys closed-loop control theory to the green wave coordinatedcontrol in city expressway, forming a closed-loop green linkage control, and solving thecity expressway "slow" problem. That is to use the modern video technology to detectthe delay of vehicles running through the intersection and feedback to the signalmachine, optimize the phase by useing "hill-climbing" constantiy,though it, we got thebest signal control plan. Finally, an example of the use of vissim simulation software tosimulate the closed-loop control, through comparative analysis between the open-loopcontrol and closed-loop control to verify the effectiveness of this method. Basing on the research, This paper proposes a suitable control method continuousurban freeway intersection of a method, the use of intelligent transportation is aneffective means to solve urban traffic problems, this study anchored, further closed-loopcontrol theory applied to traffic control.