关键词: 交通工程, 连续点排队模型, 排队系统, 流体逼近, 离散化, 非负排队, 先进先出

Abstract:

Dynamic link traffic flow loading is an essential component in the dynamic traffic assignment. In the loading models, point-queue model is widely used in discrete-time or continuous-time form. Based on the previous work, this paper briefly reviews the continuous time point queue based on the fluid approximation, which overcomes the negativity problem of original queue. Based on the observation that the original pointqueue model is actually a queuing model with a server and infinite buffer, a fluid flow approximation model is proposed to interpret the original point-queue model. Three essential components are a flow balance function, an exit flow function and a time-dependent capacity utilization ratio function, which are all in continuous form. Finally, with the discretization of the proposed model, outflow and queue are simulated on the link in three different scenarios, and the non-negativity of queue and flow first in first out (FIFO) can be easily observed.

Key words: traffic engineering, continuous point-queue model, queueing system, fluid approximation, discretization, non-negativity of queue, FIFO