Traffic Flow Analysis And Control Methods For Urban Freeway Main Lane & Auxiliary Lane

Urban freeway is a closed system, which links urban road by overpasses and ramps. With the surge in traffic demand, in addition, China doesn't have a uniform freeway construction standard at present, the freeway joins completed have complex characteristics of organization and are likely to occur congestion. In order to better coordinate the resource of urban freeway main lane and auxiliary lane, it is necessary to study urban road systems and freeway system operation law and their relations in-depth.Diamond interchange, one common form of urban and ground transportation link is the subjects of this article. First, the characteristics of freeway, ramps and auxiliary lane were analyzed, the effects of main road traffic and the steering ratio, auxiliary lane, expand length & waving ratio, control method were proposed. The on-ramp control is proposed based on queue length limit by ALINEA, and Kalman filter estimated the vehicle count, the effectiveness of control was verified through example.In the case of queue spillback in off-ramp, control strategy was introduced respectively by ramp-closed and auxiliary lights based on ALINEA.The results were analyzed and compared, which showed that both the strategy can avoid queuing spillback phenomenon,however auxiliary signal control strategy is better on the impact of mainline traffic flow.In the on-ramp control region, considered that the classic on-ramp control method-ALINEA lacking of ramp queue length constraints which could easily lead to the shortcomings of long ramp queues; The popular Queue Override Strategy abroad is a rough adjustment which not truly a queue length feedback mechanism. Based on the introduction of queue length constraints formula, and the volume in diamond interchange and on-ramp are related, Kalman filtering was used to forecast the important parameters of the formula--ramp demand. Finally, simulated ALINEA, Queue Override and ALINEA improved by VAP programming languages in VIS SIM, Simulation results show that compared with the previous two methods, Simulation results shows that compared with the previous two methods, the queue length is lower in improved ALINEA method, and the indicators are optimum.