To achieve the refinement of urban traffic signal coordination control, the selection of coordinated object should not just focus on the subarea, but needs to be further refined to the attachments of direction paths. In this paper, first, a concept system reflecting the directional demand of coordination control was established by defining the coordination path, the coordination path chain and the coordination path set, as well as the parent path and sub path which constitute the path chain. Then, the counting method of path chains was analyzed. Moreover, according to the trajectory distribution of vehicles in the road network, the corresponding optimization rules and processes of coordination path set were established from the perspective of the intersections' number (namely the length of the path chain) and the traffic flow carried by the path chain. The results of example analysis show that the proposed method can select the main path chains with large flow in the control area according to the number of intersections to be coordinated and the flow of traffic path, which can further enrich the division theory of control sub area and intersection group.

As an emergent traffic detection device, millimeter wave radar is little affected by environmental factors (e. g., light and weather) and can provide reliable data support for road traffic sensing, safety control and signal timing optimization. Vehicle trajectory data collected by millimeter wave radar contains rich traffic information, reflecting spatial-temporal characterization of vehicle motion, which is critical in traffic parameter extraction, abnormal detection, driving behavior analysis, signal timing optimization, etc. Aiming at solving the problems such as trajectory fragmentation and poor valid tracking rate caused by the vehicle data loss and easy occlusion of vehicles detected by millimeter wave radar in the intersection, this paper proposed a continuous tracking method of vehicle trajectory based on short trajectory fragment associations. Firstly, the 2D point cloud data with high frequency collected by millimeter wave radar at the intersection was acquired and cleaned to obtain valid target information. Secondly, short track fragments were extracted from 2D point clouds by inter-frame association, and multiple movement sequence feature was used for track fragment correction to reject split trajectories. Thirdly, the fuzzy correlation function was constructed based on the motion characteristics of the spatio-temporal dimension to describe the correlation among multiple short track fragments. Hungarian algorithm was employed to solve the set of target short track with the highest correlation. Finally, the missing trajectory points in the vehicle tracklet set were repaired based on the piecewise cubic Hermite interpolation, which derived complete trajectories and achieved continuous tracking. The experiments were conducted using 6627 frames of 2D point cloud data collected at the real intersection. The results indicate that the proposed method achieves better tracking performance under different traffic densities, monitoring directions, and occlusions than the traditional trajectory tracking algorithm. Specifically, the trajectory tracking accuracy is 92.4%, the number of fragmentations is 4.5, and the accuracy of estimated vehicle volume is significantly improved.

When there is a saturated intersection on the arterial road, it is necessary to intercept and regulate the traffic flow in the entry direction of the saturated intersection, so as to avoid the overflow of the section queue, and to conduct green wave dredging in the exit direction of the saturated intersection to facilitate the rapid departure of traffic flow. According to the coordination control requirements in different directions of saturated intersection, this paper proposed an algebraic method of coordination design for bi-directional red and green waves on arterial roads. Firstly, the general formula for calculating the ideal intersection distance was derived by using the time-space diagram, and the calculation method of bias-split for the coordinated phase was given. Secondly, for different common signal cycles,the bias-split for the coordinated phase under different signal phase modes of each intersection was calculated respectively. The signal phase mode corresponding to the bias-split with the smallest absolute value was taken as the preferred phase of each intersection. Then, the max difference of bias-split corresponding to the preferred phase under different common signal cycles was compared, and the common signal cycle with the minimum of the max difference of bias-split was selected as the best common signal cycle. Finally, based on the characteristics of red and green waves, the optimization method of fine-tuning signal offsets was given to minimize the bias-split of the green wave direction, so as to ensure that the arterial road can obtain bi-directional red and green wave bandwidth as wider as possible. The case analysis shows that, compared with the scheme of bi-directional green wave coordinated control, the bi-directional red and green waves coordinated control scheme designed by this method can significantly increase the green wave bandwidth in the direction of leaving the saturated intersection while ensuring that there is a maximum red wave bandwidth in the direction of entering the saturated intersection. The VISSIM simulation experiment shows that the scheme designed by this method can not only shorten the maximum queue length by 23.1% and the average queue length by 33.8%, and delay the time of vehicles queuing to overflow to the upstream intersection, but also reduce the travel time and the number of stops of the vehicles leaving at the saturated intersection in the downstream section by 17.5% and 76.3%, respectively. It can realize the overflow prevention and green wave dredging of the saturated intersection.