| With the continued increase of urban traffic demand, the accompanying traffic congestion increasingly becomes the focus of the road design and managers. How to effectively lower travel cost, reduce traffic congestion and improve traffic efficiency is increasingly important. Considering the road space and construction limits, interchange are not available in many intersections. Hence intersections with effective signal control is necessary to ensure traffic safety and orderly release. In this paper, based on the idea of lane sharing, dynamic utilization of lane resources through reorganizing traffic flows is proposed to share the lanes in approach and hence improve the capacity or decrease the average delay. To achieve this goal, combining the lane allocation with the signal timing plan is incorporated in the joint optimization model.Lane sharing can appear in different forms, depending on the way to reorganize traffic flow. In this paper, three configurations of lane sharing combined with traffic reorganization and signal timing are proposed to achieve dynamic utilization of lane resource.The first configuration is signalized intersection with waiting areas. Waiting areas of intersection are commonly established in urban cities of China. The waiting area can function as a buffer zone in protected phase to ensure the safe and efficient discharge of vehicles in shared-use lane. The shared-use lane designation is hence incorporated in an off-line signal optimization model. The optimal results proved that the method is equivalent to providing some additional lane for vehicles. Therefore, the capacity is improved. However, due to the restricted number of shared-use lane, the incremental capacity is limited.The second configuration is tandem with pre-signal. The tandem intersection can fully share the lanes in sorting area, hence the*capacity improvement is significant. In theory, the configuration is equivalent to serving all lanes for vehicles. However, this method requires the proper coordination between the pre-signal and the main signal, which will inevitably produce additional delays. In this paper, a common approach for lane allocation, signal timing, signal sequence selection is formulated and a joint optimization model is presented. The optimized results demonstrate the advantages of such full lane sharing configuration.The third one is median U-turn intersection with protected pre-signal. This method reduces the number of phases in the main signal, and therefore significantly reduce the average delay of vehicles. By constraining the allocation of lanes, traffic capacity match, buffer capacity constraints, the vehicles can be orderly and safely discharged. The comparison between the configuration and the conventional intersection verifies that the advantage of lane sharing. Even compare with conventional intersection with more lanes, the performance of shared-use median U-turn intersection with protected pre-signal is better.The idea of lane sharing in signalized intersection combined with signal timing proves to enhance the capacity or reduce delays, hence enrich the theory and practice of intersection control. However, how should traffic flows be reorganized and how the lane sharing be utilized, for instance, combined with unconventional intersection, still needs further research. |
