The Experts below are selected from a list of 19254 Experts worldwide ranked by ideXlab platform
Satoshi Yukawa - One of the best experts on this subject based on the ideXlab platform.
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Critical Density of Experimental Traffic Jam
Traffic and Granular Flow '13, 2014Co-Authors: Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Akihiro Nakayama, Katsuhiro Nishinari, Akihiro Shibata, Yuki Sugiyama, T Yosida, Satoshi YukawaAbstract:In a previous experiment, we have demonstrated that a Traffic Jam emerges without any bottleneck at a certain high density. In the present work, we performed an indoor circuit experiment in Nagoya Dome and estimated the critical density. The circuit is large (314 m in circumference) compared to the previous experiment. Positions of cars were observed in 0.16 m resolution. We performed 19 sessions by changing the number of cars from 10 to 40. We found that Jammed flow was realized in high density while free flow in low density. We also found the indication of metastability at an intermediate density. The critical density is estimated by analyzing the density-flow relation. The critical density locates between 0. 08 and 0. 09 m−1. It is consistent with that observed in real expressways.
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Phase transition in Traffic Jam experiment on a circuit
New Journal of Physics, 2013Co-Authors: Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Akihiro Nakayama, Katsuhiro Nishinari, Akihiro Shibata, Yuki Sugiyama, T Yosida, Satoshi YukawaAbstract:The emergence of a Traffic Jam is considered to be a dynamical phase transition in a physics point of view; Traffic flow becomes unstable and changes phase into a Traffic Jam when the car density exceeds a critical value. In order to verify this view, we have been performing a series of circuit experiments. In our previous work (2008 New J. Phys. 10 033001), we demonstrated that a Traffic Jam emerges even in the absence of bottlenecks at a certain high density. In this study, we performed a larger indoor circuit experiment in the Nagoya Dome in which the positions of cars were observed using a high-resolution laser scanner. Over a series of sessions at various values of density, we found that Jammed flow occurred at high densities, whereas free flow was conserved at low densities. We also found indications of metastability at an intermediate density. The critical density is estimated by analyzing the fluctuations in speed and the density–flow relation. The value of this critical density is consistent with that observed on real expressways. This experiment provides strong support for physical interpretations of the emergence of Traffic Jams as a dynamical phase transition.
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metastability in the formation of an experimental Traffic Jam
New Journal of Physics, 2009Co-Authors: Akihiro Nakayama, Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Katsuhiro Nishinari, Yuki Sugiyama, Katsuya Hasebe, Satoshi YukawaAbstract:We show detailed data about the process of Jam formation in a Traffic experiment on a circuit without any bottlenecks. The experiment was carried out using a circular road on a flat ground. At the initial stage, vehicles are running homogeneously distributed on the circuit with the same velocity, but roughly 10 min later a Traffic Jam emerges spontaneously on the circuit. In the process of the Jam formation, we found a homogeneous flow with large velocity is temporarily realized before a Jam cluster appears. The instability of such a homogeneous flow is the key to understanding Jam formation.
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Detailed Data of Traffic Jam Experiment
Traffic and Granular Flow ’07, 2009Co-Authors: Akihiro Nakayama, Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Katsuhiro Nishinari, Yuki Sugiyama, Katsuya Hasebe, Satoshi YukawaAbstract:We show detailed data of two Traffic Jam experiments on a circuit. In the experiments, a Traffic Jam emerges spontaneously without any bottlenecks. We found the power law nature in time series of average velocity, and also found the homogeneous flow with large velocity is temporarily made before a Jam cluster is formed.
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Traffic Jams without bottlenecks—experimental evidence for the physical mechanism of the formation of a Jam
New Journal of Physics, 2008Co-Authors: Yuki Sugiyama, Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Akihiro Nakayama, Katsuhiro Nishinari, Katsuya Hasebe, Satoshi YukawaAbstract:A Traffic Jam on a highway is a very familiar phenomenon. From the physical viewpoint, the system of vehicular flow is a non-equilibrium system of interacting particles (vehicles). The collective effect of the many-particle system induces the instability of a free flow state caused by the enhancement of fluctuations, and the transition to a Jamming state occurs spontaneously if the average vehicle density exceeds a certain critical value. Thus, a bottleneck is only a trigger and not the essential origin of a Traffic Jam. In this paper, we present the first experimental evidence that the emergence of a Traffic Jam is a collective phenomenon like 'dynamical' phase transitions and pattern formation
Richard Woesler - One of the best experts on this subject based on the ideXlab platform.
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Still Flowing: Approaches to Traffic Flow and Traffic Jam Modeling
Operations Research, 2003Co-Authors: K. Nagel, Peter Wagner, Richard WoeslerAbstract:Certain aspects of Traffic flow measurements imply the existence of a phase transition. Models known from chaos and fractals, such as nonlinear analysis of coupled differential equations, cellular automata, or coupled maps, can generate behavior which indeed resembles a phase transition in the flow behavior. Other measurements point out that the same behavior could be generated by geometrical constraints of the scenario. This paper looks at some of the empirical evidence, but mostly focuses on different modeling approaches. The theory of Traffic Jam dynamics is reviewed in some detail, starting from the well-established theory of kinematic waves and then veering into the area of phase transitions. One aspect of the theory of phase transitions is that, by changing one single parameter, a system can be moved from displaying a phase transition to not displaying a phase transition. This implies that models for Traffic can be tuned so that they display a phase transition or not. This paper focuses on microscopic modeling, i.e., coupled differential equations, cellular automata, and coupled maps. The phase transition behavior of these models, as far as it is known, is discussed. Similarly, fluid-dynamical models for the same questions are considered. A large portion of this paper is given to the discussion of extensions and open questions, which makes clear that the question of Traffic Jam dynamics is, albeit important, only a small part of an interesting and vibrant field. As our outlook shows, the whole field is moving away from a rather static view of Traffic toward a dynamic view, which uses simulation as an important tool.
Shiqiang Dai - One of the best experts on this subject based on the ideXlab platform.
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Traffic Jam Formation in Traffic Flow on a Harbor Tunnel
Computational Mechanics, 2007Co-Authors: Li-yun Dong, Shiqiang DaiAbstract:A study on the occurrence and growth of Traffic Jams on a single-lane in the tunnel by using the optimal-velocity Traffic model [1, 2, 3] is reported in this paper. At the low vehicle density, the current increases linearly with density and saturates at certain values of density range. As the vehicle density increases, the Traffic Jam appears firstly before the uphill section and extends to the downhill section with the increasing density. The relationships of velocity against position in different vehicle density are obtained from simulations, which clarifies clearly where and when the Traffic Jam occurs. We also derived the critical densities before and after the discontinuous fronts from the theoretical current curves. These values also comply with the results of simulation [4]. The study will be useful to provide suggestions for engineer to control the range of vehicle density in tunnel to avoid the Traffic Jam.
Katsuhiro Nishinari - One of the best experts on this subject based on the ideXlab platform.
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Critical Density of Experimental Traffic Jam
Traffic and Granular Flow '13, 2014Co-Authors: Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Akihiro Nakayama, Katsuhiro Nishinari, Akihiro Shibata, Yuki Sugiyama, T Yosida, Satoshi YukawaAbstract:In a previous experiment, we have demonstrated that a Traffic Jam emerges without any bottleneck at a certain high density. In the present work, we performed an indoor circuit experiment in Nagoya Dome and estimated the critical density. The circuit is large (314 m in circumference) compared to the previous experiment. Positions of cars were observed in 0.16 m resolution. We performed 19 sessions by changing the number of cars from 10 to 40. We found that Jammed flow was realized in high density while free flow in low density. We also found the indication of metastability at an intermediate density. The critical density is estimated by analyzing the density-flow relation. The critical density locates between 0. 08 and 0. 09 m−1. It is consistent with that observed in real expressways.
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Phase transition in Traffic Jam experiment on a circuit
New Journal of Physics, 2013Co-Authors: Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Akihiro Nakayama, Katsuhiro Nishinari, Akihiro Shibata, Yuki Sugiyama, T Yosida, Satoshi YukawaAbstract:The emergence of a Traffic Jam is considered to be a dynamical phase transition in a physics point of view; Traffic flow becomes unstable and changes phase into a Traffic Jam when the car density exceeds a critical value. In order to verify this view, we have been performing a series of circuit experiments. In our previous work (2008 New J. Phys. 10 033001), we demonstrated that a Traffic Jam emerges even in the absence of bottlenecks at a certain high density. In this study, we performed a larger indoor circuit experiment in the Nagoya Dome in which the positions of cars were observed using a high-resolution laser scanner. Over a series of sessions at various values of density, we found that Jammed flow occurred at high densities, whereas free flow was conserved at low densities. We also found indications of metastability at an intermediate density. The critical density is estimated by analyzing the fluctuations in speed and the density–flow relation. The value of this critical density is consistent with that observed on real expressways. This experiment provides strong support for physical interpretations of the emergence of Traffic Jams as a dynamical phase transition.
-
metastability in the formation of an experimental Traffic Jam
New Journal of Physics, 2009Co-Authors: Akihiro Nakayama, Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Katsuhiro Nishinari, Yuki Sugiyama, Katsuya Hasebe, Satoshi YukawaAbstract:We show detailed data about the process of Jam formation in a Traffic experiment on a circuit without any bottlenecks. The experiment was carried out using a circular road on a flat ground. At the initial stage, vehicles are running homogeneously distributed on the circuit with the same velocity, but roughly 10 min later a Traffic Jam emerges spontaneously on the circuit. In the process of the Jam formation, we found a homogeneous flow with large velocity is temporarily realized before a Jam cluster appears. The instability of such a homogeneous flow is the key to understanding Jam formation.
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Detailed Data of Traffic Jam Experiment
Traffic and Granular Flow ’07, 2009Co-Authors: Akihiro Nakayama, Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Katsuhiro Nishinari, Yuki Sugiyama, Katsuya Hasebe, Satoshi YukawaAbstract:We show detailed data of two Traffic Jam experiments on a circuit. In the experiments, a Traffic Jam emerges spontaneously without any bottlenecks. We found the power law nature in time series of average velocity, and also found the homogeneous flow with large velocity is temporarily made before a Jam cluster is formed.
-
Traffic Jams without bottlenecks—experimental evidence for the physical mechanism of the formation of a Jam
New Journal of Physics, 2008Co-Authors: Yuki Sugiyama, Shin-ichi Tadaki, Macoto Kikuchi, Minoru Fukui, Akihiro Nakayama, Katsuhiro Nishinari, Katsuya Hasebe, Satoshi YukawaAbstract:A Traffic Jam on a highway is a very familiar phenomenon. From the physical viewpoint, the system of vehicular flow is a non-equilibrium system of interacting particles (vehicles). The collective effect of the many-particle system induces the instability of a free flow state caused by the enhancement of fluctuations, and the transition to a Jamming state occurs spontaneously if the average vehicle density exceeds a certain critical value. Thus, a bottleneck is only a trigger and not the essential origin of a Traffic Jam. In this paper, we present the first experimental evidence that the emergence of a Traffic Jam is a collective phenomenon like 'dynamical' phase transitions and pattern formation
K. Nagel - One of the best experts on this subject based on the ideXlab platform.
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Still Flowing: Approaches to Traffic Flow and Traffic Jam Modeling
Operations Research, 2003Co-Authors: K. Nagel, Peter Wagner, Richard WoeslerAbstract:Certain aspects of Traffic flow measurements imply the existence of a phase transition. Models known from chaos and fractals, such as nonlinear analysis of coupled differential equations, cellular automata, or coupled maps, can generate behavior which indeed resembles a phase transition in the flow behavior. Other measurements point out that the same behavior could be generated by geometrical constraints of the scenario. This paper looks at some of the empirical evidence, but mostly focuses on different modeling approaches. The theory of Traffic Jam dynamics is reviewed in some detail, starting from the well-established theory of kinematic waves and then veering into the area of phase transitions. One aspect of the theory of phase transitions is that, by changing one single parameter, a system can be moved from displaying a phase transition to not displaying a phase transition. This implies that models for Traffic can be tuned so that they display a phase transition or not. This paper focuses on microscopic modeling, i.e., coupled differential equations, cellular automata, and coupled maps. The phase transition behavior of these models, as far as it is known, is discussed. Similarly, fluid-dynamical models for the same questions are considered. A large portion of this paper is given to the discussion of extensions and open questions, which makes clear that the question of Traffic Jam dynamics is, albeit important, only a small part of an interesting and vibrant field. As our outlook shows, the whole field is moving away from a rather static view of Traffic toward a dynamic view, which uses simulation as an important tool.
