• tandem intersection;
  • lane assignment;
  • signal timing;
  • delay estimation


This paper presents an integrated model for optimizing lane assignment and signal timing at tandem intersection, which is introduced recently. The pre-signal is utilized in the tandem intersection to reorganize the traffic flow; hence, the vehicles, regardless of whether left-turns or through vehicles, can be discharged in all the lanes. However, the previous work does not consider the extra traffic disruption and the associated delay caused by the additional pre-signal. In the paper, the extra delay aroused by the coordination is incorporated in a lane assignment and signal timing optimization model, and the problem is converted into a mixed-integer non-linear programming. A feasible directions method is hence introduced to solve the mixed-integer non-linear programming. The result of the optimization shows that the performance of the tandem intersection is improved and the average delay is minimized. The comparison between the tandem and the conventional configuration is presented, and the results verify that the former shows better performance than the latter. In addition, the optimal sequence corresponding to the turning proportion and the optimal lane assignment at the upstream approach of the pre-signal are presented. Furthermore, if the number of lanes is equal in all arms, the paper proves that the average delay will be reduced if lane assignment is proportional to the turning proportion and the vehicles with low proportion are discharged in advance. Copyright © 2013 John Wiley & Sons, Ltd.