基于二流理论的拥挤交通流当量排队长度模型

为描述拥挤交通流中的排队现象,根据二流理论,提出了将交通流实际运行状态转化为二流运行状态的思想.利用流量守恒方程,建立了单车道路段当量排队长度模型,并在此基础上,推导出多车道路段平均当量排队长度模型.为验证模型的有效性,采用VISSIM软件设计了拥挤交通流的模拟方案.对比模型计算的当量排队长度与软件统计的实际排队长度发现:当量排队长度均大于实际排队长度;当量排队长度比较稳定,而实际排队长度有所波动.结果表明,当量排队长度模型能够定量地、更好地描述拥挤路段的交通流拥挤程度.该模型计算方法简单,便于工程实践,可以为城市交通控制系统优化等提供理论依据.

Equivalent queue length model for congested traffic stream based on two-fluid theory

To describe the queue phenomena in congested traffic flow, based on two-fluid theory a thinking which converts actual traffic-flow operation state into two-fluid operation state is put forward.The equivalent queue length model is built for a single-lane segment according to conservation equation.On this basis,the average equivalent queue length model is educed for a multi-lane segment.To validate the effectiveness of the models,the simulation schemes are designed for the congested traffic flow by applying the VISSIM software.By comparing the equivalent queue lengths computed by the models with the actual queue lengths obtained by the software,it is found that the equivalent queue lengths are all longer than the actual ones;the equivalent queue lengths are stable,but the actual values fluctuate.The results show that the equivalent queue length models can quantitatively and better describe the congested degree of traffic-flow on congested segment.The models are simple and easy to be applied in engineering practice.Their results can provide a theoretical basis for urban traffic control system optimization etc.