Research On The Key Technique Of Signal Control In Oversaturation Traffic Status

With the city ’s economic development, the vehicle in the city is growing rapid,but the growth of urban roads is limited and slow. It causes the traffic jams and thetravel time is increasing. The traffice oversaturation has been normal in the city. Sohow to take effective measures to alleviate the traffic problem from a system point ofview has become a new requirement for development. Considering the defects inexisting theory and method of oversaturation signal control, combining with thecharacteristics of oversaturation traffic, this dissertation has researched and discussedin the following areas, including the indentification of oversaturation traffic, a singleintersection control model in oversaturation, arterial coordination control model inoversaturation, the intersection group coordination control and so on. The mainscientific research and research results in this dissertation include:1. By analyzing a variety of different oversaturated objects, the definition ofoversaturation is given, and the traffic characteristics, such as high green time usagerate, approach queue accumulation and the increasing vehicle delay, are illustrated inoversaturation. Using the characterist of the long queue length, the identificationmethod of oversaturation based on the the maximum queue length is proposed, whichis easy to take out but there are some limitations. In order to more effectively identifyoversaturation, a retention queue length predictive model and the upstreamintersection overflow prediction model are establish using the detection data of thedetector, and based on these two models two traffic parameters(queue dissipationfactor and the overflow block coefficient) is calculated which describe theoversaturation status. By the numerical example these two factors are verified thatthey can effectively identify the traffic state of oversaturation.2. Four different control strategies in oversaturation are respectively discussed,which including traffic signal control dynamically for single intersection, equal queuelengths, active queue control, delay minimization control. Based on the minimum ofdelay, and taking the other three kinds of strategy into account, the continuous controldelays model and the discrete control model are established. For the continuous delaycontrol model which is based on a continuous traffic flow，the overall intersectiondelay model is built by the approach deley calculation, and the method to obtain theintersection optimal control scheme is indicated. For the discrete delay control model which is based on the unit time traffic flow, the intersection control model isestablished by the the overall delay calculation, the genetic algorithm and theconversion algorithm are designed to strike the discrete model. Finally, thereasonabilty of the discrete control model is illustrated through the numercialexample.3. The objective function of the one-way coordination control model is proposed,whose objective is the the arterial maximum capacity. Four different queuing controlstrategies in oversaturation is pointed out, and based on those the one-waycoordination control model is built. Under the premise of the one-way model, theother direction of the arterial has thress status, such as roads blocked, trafficcompensation and wasted green time. In the different traffic status, the calculations ofthe approach volume are established. So combining with the constraints in bothdirections, the bidirectional coordination control model in oversaturation isestablished, which is priority to the main direction in arterial. By the numericalexample, the control effect in different queueing strategies are analyzed, and the prosand cons of four strategies are also Comparatively analyzed, and those can verify thecorrectness of the model.4. The oversaturation coordination control method of the crossing arterial isanalyzed, the way of using different priority levels to achieve coordination in crossingarterial is proposed, and the calculation process of weight coefficient of the differentpriority level arterial is designed. The crossing arterial can divide to sub-area andsection set, so the coordination control sub-area division method and the section setbetween sub-area are introducted, and the parameter definitions of those coordinatedcontrol basic unit are introducted. The coordination control procedures is designed,which start from the biggest weigh sub-area and gradually merger other sub-areasuntil the entire region merging based on the weigh of section. Then based thecoordination control steps, the crossing arterial coordination control model isestablished, and the implementation process of the model is further illustrated by thenumerical example.5. The population dynamics theory and methods is analyzed, and thecoordination control method of intersection group is proposed by using hierarchicalcoordinated approach, dynamically adjust, optimize the intersection cycle and greensplit. Based on population dynamics, the optimal adjustment dynamics operator ofintersection green split is established, and whose stability is analyzed and explanated. The conditions of the oversaturation intersection group merger and separation aredefinited, the adjustment algorithms of the cycle and green split for these two casesare designed. Integrating these two algorithms, the overall dynamic oversaturationcoordination control algorithm is established. The intersection group coordinationcontrol model is built based on the queuing delay minimum, and whose optimizationsolving process is indicated. Finally, take the Guangzhou Zhongshan Road for examle,the optimal solution result of the model is illustrated, and compared with thecoordination effect of the MAXBAND and TRANSYT-7F, the superiority of themodel is described.6. Taking the Tian-He-Bei Road in Guangzhou Tianhe District as a case, theoversaturated traffic status of the Tian-He-Bei Road is identificated using theoversaturated traffic identification method, the split of all the intersections isoptimized by the delay control model and the arterial signal program is optimized bythe arterial coordination control model. So, using the traffic simulation, thecorrectness and practicality of the research is verified by analyzing the delay andnumber of stop in defferent states, such as before improvement, on green wavecoordination control and improvement.