Abstract: In order to release traffic flow of urban road, a new hierarchical dynamic coordination control technique is proposed. Firstly, the whole urban road is divided into three hierarchies vertically：ramp hierarchy, ordinary road hierarchy and the mainline of urban expressway hierarchy. Then, BP neural network is used to forecast dynamic critical occupancy rate of downstream, and according to dynamic critical occupancy rate of downstream and the on-ramp queue length, the subarea partition function is designed, by which the ramp hierarchy is divided into the main control subarea and the secondary control subarea horizontally; the ordinary road hierarchy is divided into several control subareas horizontally by calculating correlation of adjacent intersection, and the Webster cycle formula is improved according to the dynamic traffic flow data, considering the traffic flow from intersection to ramp, the green ratio is optimized; the mainline of urban expressway hierarchy is not divided horizontally because of the lack of the intersection. Finally, the dynamic coordinated control algorithm is given and simulation shows that the proposed method can effectively improve the coordination control range and the vehicle speed.

Key words: ordinary road hierarchy, ramp hierarchy, mainline of urban expressway hierarchy, control subarea, main ramp, secondary ramp

摘要： 为了缓解城市道路车流拥堵问题，提出了一种城市道路分层动态协调控制技术。首先将城市道路按纵向分为三层：匝道层、普通道路层和快速路主线层；然后采用BP神经网络预测下游动态临界车辆占有率，根据匝道相对排队长度和下游动态临界车辆占有率，匝道层设计了一种用于匝道子区划分的函数，将匝道层横向分为主匝道子区和从匝道子区；其次根据相邻路口关联度将普通道路层划分为不同控制子区，利用动态交通流数据修正周期公式，考虑十字交叉口驶向匝道车流量对绿信比进行调整；快速路主线层无十字交叉口不做横向分层。最后根据该分层方法确定动态协调控制算法。仿真结果表明：该分层动态协调控制方法能够有效提高城市道路协调控制范围和车辆行车速度。

关键词: 匝道层, 普通道路层, 快速路主线层, 控制子区, 主匝道, 从匝道