Collaborative Research: Phantom traffic jams, continuum modeling, and connections with detonation wave theory

合作研究：虚拟交通堵塞、连续介质建模以及与爆震波理论的联系

• 批准号: 1007899
• 负责人: Benjamin Seibold
• 金额: $ 10.73万
• 依托单位: Temple University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1007899&HistoricalAwards=false
• 关键词: Collaborative; Research; Phantom; traffic; jams

Initially homogeneous traffic flow can become inhomogeneous even in the absence of obstructions of any kind, leading to the formation of ''phantom'' traffic jams. Phantom traffic jams can be explained as instabilities that occur in certain types of macroscopic traffic models. Under appropriate conditions, if the traffic density exceeds a critical threshold value, small perturbations amplify and grow into nonlinear traveling waves. These traffic waves, called jamitons, are observed in reality and have been reproduced experimentally. In this project, a mathematical analogy between jamitons and detonation waves in reacting gas dynamics is established and exploited: phantom traffic jams are the analogs of instabilities in the fluid's motion, and jamitons are the analogs of detonation waves. Using the Zel'dovich-von Neumann-Doering theory from combustion theory, the analogy allows the prediction of the exact shape and travel velocity of the jamitons. A key feature in the analysis is the presence of a sonic point, which acts as an event horizon (similar to the one that occurs in a black hole) across which information cannot propagate. Traffic waves are studied theoretically and by numerical simulations. A particular goal is to understand phantom traffic jams well enough to allow the development of effective countermeasures.A ''phantom'' traffic jam is a small congestion in vehicular traffic that occurs spontaneously, in the absence of bottlenecks, obstacles, or any discernible causes on the road. Observations show that uniform traffic flow can develop inhomogeneities, which turn into traveling traffic jams. These traffic jam waves (''jamitons'') enforce unexpected braking maneuvers, and thus impose stress on drivers and materials, waste fuel and increase pollution, and are hot spots for potential vehicle collisions. In this project, the behavior of phantom traffic jams and jamitons is studied. Theoretical analogies between traffic modeling and gas dynamics, hydraulics, and astrophysics, are established and used to advance the understanding of traffic flow. These connections yield insight into the situations under which phantom traffic jams can occur, and allow the prediction of the shape and velocity of the resulting jamitons. A fundamental understanding of phantom traffic jams is a key step in devising appropriate countermeasures to avoid or ameliorate them. The development of effective ways to manage or prevent phantom traffic jams could have a considerable impact on the reduction of fuel consumption and pollution. Two possible strategies that will be incorporated into the models and investigated are: assisted driving devices in the individual vehicles, and adaptively controlled speed limits on highways. A crucial component of this study is the interplay between theoretical analysis and numerical experiments. The research in this project involves three international collaborations, as well as graduate and undergraduate research projects.

最初均匀的交通流即使在没有任何障碍物的情况下也会变得不均匀，从而导致“幻影”交通堵塞的形成。幻影交通堵塞可以解释为发生在某些类型的宏观交通模型中的不稳定性。在适当的条件下，如果交通密度超过临界阈值，小扰动放大并成长为非线性行波。这些交通波，称为干扰，在现实中观察到，并已被实验重现。在这个项目中，建立并利用了反应气体动力学中的干扰和爆震波之间的数学类比：幻影交通堵塞是流体运动中的不稳定性的类比，干扰是爆震波的类比。使用燃烧理论中的Zel'dovich-von Neumann-Doering理论，该类比允许预测干扰子的确切形状和行进速度。分析中的一个关键特征是存在一个声波点，它作为一个事件视界（类似于黑洞中发生的事件视界），信息不能传播。对交通波进行了理论分析和数值模拟。一个特别的目标是充分了解幻影交通堵塞，以便制定有效的对策。“幻影”交通堵塞是在没有瓶颈、障碍物或道路上任何可识别的原因的情况下自发发生的车辆交通中的小拥堵。观察表明，均匀的交通流可能会发展出不均匀性，从而导致交通堵塞。这些交通堵塞波（“堵塞”）强制执行意外的制动操作，从而对驾驶员和材料施加压力，浪费燃料并增加污染，并且是潜在车辆碰撞的热点。在这个项目中，幻影交通堵塞和拥堵的行为进行了研究。交通建模和气体动力学，水力学和天体物理学之间的理论类比，建立和用于推进交通流的理解。这些连接产生洞察的情况下，幻影交通堵塞可能发生，并允许预测的形状和速度的结果堵塞。对幻影交通拥堵的基本理解是设计适当对策以避免或改善它们的关键一步。开发有效的方法来管理或防止虚幻的交通堵塞，可以对减少燃料消耗和污染产生相当大的影响。两种可能的策略，将被纳入模型和调查是：辅助驾驶装置在个别车辆，自适应控制的高速公路上的速度限制。本研究的一个重要组成部分是理论分析和数值实验之间的相互作用。该项目的研究涉及三个国际合作，以及研究生和本科生的研究项目。