考虑辅路缓冲的快速路紧急疏散最优控制

针对紧急疏散中单向需求激增的情况,提出利用地面辅路缓冲容纳部分疏散车流,从而降低快速路疏散的整体时空风险.基于宏观交通流模型建立了快速路疏散车流演化方程,明确了上匝道车速对主线车速的影响,从而实现经典宏观交通流模型对路网状态演变处理的一致性.针对由下匝道、地面并行道路和上匝道构成的地面辅路行程时间的二分特征,建立了相应的离散时间的流量演化方程.辅路系统方程不仅可以刻画地面辅路疏散车流的主要特征,而且能与已有快速路的状态演化系统实现无缝结合.数值分析表明,利用匝道控制和辅路分流两种手段可以实现系统整体时空疏散风险的最小化控制.

Freeway Network Optimal Control during Emergency Evacuation with Buffering of Ground Bypass

In view of the sharply increased demand during emergency evacuation, we propose using the ground bypass to buffer partial evacuating vehicles so as to lower the whole temporal and spatial risk of freeway evacuation system. Evacuating traffic evolution equations are constructed based on the macroscopic traffic flow model. In the equations, the impact of speeds of vehicles at on-ramps on the mainline traffic is clarified. This realizes the consistency of network state evolution in the macroscopic traffic flow model. In view of the dichotomy of travel time of the ground bypass consisted of an off-ramp, the parallel street road and an on- ramp, the discrete traffic flow evolution equations are constructed for the ground bypass. The above system equations can not only describe the main features of the traffic flow on the ground bypass, but also be seamlessly incorporated in the freeway state evolution system. The numerical analysis demonstrates that using the ramp metering and flow splitting to ground bypass, we can realize the minimization of the evacuation risk of the whole system.