Research On Timing Strategy Of Intelligent Traffic Lights

With the increasing number of vehicles and the restriction of urban traffic resources,traffic congestion has become one of the key problems in urban development.The intersection is the key node in the urban traffic network.Reasonable diversion and control of traffic flow at the intersection is an important way to effectively improve the traffic efficiency of city.The main method to control the traffic flow at the intersection is by traffic lights.The timing strategy is composed of two parts,the green time and the green light start time,which is the basis of traffic control at the intersection.The fixed timing strategy and adaptive timing strategy are the two main timing strategies currently used.The fixed timing strategy has the advantages of simplicity and convenience,but it can not adapt to the change of vehicle flow and effectively alleviate the traffic congestion.The adaptive timing strategy can calculate the green light time according to the prediction model to adapt to the change of traffic flow,slow down the stagnation phenomenon,and improve the traffic efficiency of the intersection.At present,the predictive models in most adaptive timing strategies are complicated,the calculated amount is large and the implementation efficiency is not high.On the basis of analyzing and summarizing the existing timing strategies,this paper studies the indefinite cycle timing strategy and adaptive shift left-turn timing strategy.The main work and contributions of this article include:(1)This paper proposes an indefinite cycle traffic light timing strategy.On the one hand,the strategy automatically adjusts the green light time of each lane according to the arriving traffic flow,and improves the traffic efficiency of the intersection by increasing the green light utilization rate.On the other hand,this strategy optimizes lane combination to facilitate traffic light control by optimizing lane order.The simulation results show that the traffic efficiency of the indefinite cycle traffic light timing strategy increases by an average of 15% compared to the fixed timing strategy.This strategy reduces vehicle retention and relieves traffic congestion.(2)This paper proposes an adaptive shift left-turn timing strategy.Automatically,this strategy firstly adjusts the green time of each lane according to the traffic flow,then chooses the most suitable cycle type according to the green light time,and finally adjusts the cycle time according to the traffic flow size.The simulation results show that the adaptive shift left-turn timing strategy proposed in this paper improves the average efficiency by 5% compared with the fixed timimg plan.And it effectively shortens the waiting time of vehicle,reduces the vehicle retention and improves the traffic condition at the intersection.(3)Compare the two strategies proposed in this paper.The evaluation of the timing strategies are carried out using the three indicators,which are vehicle average delay time,traffic efficiency and number of retained vehicles.The evaluation results show that the timing plans proposed in this paper are efficient and reliable.The delay of adaptive shift left-turn timing strategy is the smallest.And indefinite cycle timing strategy has the smallest number of retained vehicles and the highest traffic efficiency.The indefinite cycle traffic light timing strategy proposed in this paper has important reference value for studying the intersection timing strategy.And the research on adaptive shifting left-turn traffic timing strategy is a useful attempt to the current intersection traffic organization and management mode.