基于子网独立计算的两级交通分配方法

Two-phase Traffic Assignment Based on the Independent Calculation of Sub-networks

基于子网分布式计算的交通分配方法的构想,以含有一个单通道子网的简单网络为研究对象,针对子网OD对(子OD对)提出子网虚拟化和子网平衡阻抗的概念,建立了描述单通道子网平衡状态下子OD对间的阻抗和子网OD量之间关系的子网流量-平衡阻抗表,进而提出基于子网独立计算的两级交通分配方法。将子网的每个子OD对转化成相应的虚拟路段,其阻抗由事先建立的子网流量——平衡阻抗表确定,然后对虚拟化后的网络进行一级分配。根据一级分配得到的各虚拟路段的流量,对各子网进行二级分配。分析表明,子网虚拟化后的网络得到简化,而且考虑到各子网规模的相对较小以及一些二级分配可以并发进行,以提高分配速度。

Based on distributed calculations of sub-networks, taking a simple network with a one-passage sub-network as research object, the process of turning a sub-network into a virtual link is introduced according to a corresponding sub-OD pair. The flow-equilibrium impedance table of sub-network can be established which describes the relationship between the impedance and OD values of a one-passage sub-network under equilibrium condition. The approach of two-phase assignment is proposed based on the independent calculation of sub-network. The object of the first-phase assignment is the original network with a virtual link resulting from the sub-network,whose impedance can be obtained from the table directly. The second-phase assignment begins in the sub-network using the flow result of the virtual link from the first-phase. An example is provided and the results indicate that the assignment process is improved considering the simplification of the original network after the virtual process, the comparatively small scales of sub-networks and some of them can manage the second-phase assignment simultaneously.