Treiber Martin, Kesting Arne, Helbing Dirk
Dresden University of Technology, Andreas-Schubert-Strasse 23, 01062 Dresden, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Jul;74(1 Pt 2):016123. doi: 10.1103/PhysRevE.74.016123. Epub 2006 Jul 31.
We investigate the adaptation of the time headways in car-following models as a function of the local velocity variance, which is a measure of the inhomogeneity of traffic flow. We apply this mechanism to several car-following models and simulate traffic breakdowns in open systems with an on-ramp as bottleneck and in a closed ring road. Single-vehicle data and one-minute aggregated data generated by several virtual detectors show a semiquantitative agreement with microscopic and flow-density data from the Dutch freeway A9. This includes the observed distributions of the net time headways for free and congested traffic, the velocity variance as a function of density, and the fundamental diagram. The modal value of the time headway distribution is shifted by a factor of about 2 under congested conditions. Macroscopically, this corresponds to the capacity drop at the transition from free to congested traffic. The simulated fundamental diagram shows free, synchronized, and jammed traffic, and a wide scattering in the congested traffic regime. We explain this by a self-organized variance-driven process that leads to the spontaneous formation and decay of long-lived platoons even for a deterministic dynamics on a single lane.
我们研究了跟驰模型中车头时距的适应性，它是交通流不均匀性的一种度量，是局部速度方差的函数。我们将此机制应用于多个跟驰模型，并在以匝道为瓶颈的开放系统和封闭环形道路中模拟交通拥堵。由多个虚拟探测器生成的单车数据和一分钟汇总数据与荷兰A9高速公路的微观和流量-密度数据显示出半定量的一致性。这包括自由流和拥堵交通状态下净车头时距的观测分布、速度方差随密度的变化以及基本图。在拥堵条件下，车头时距分布的众数大约会偏移2倍。从宏观上看，这对应于从自由流到拥堵交通转变时的通行能力下降。模拟的基本图显示了自由流、同步流和拥堵流，并且在拥堵交通状态下存在较大的离散度。我们通过一个自组织的方差驱动过程来解释这一现象，即使在单车道的确定性动力学情况下，该过程也会导致长寿命车队的自发形成和消散。
