Metastability in the formation of an experimental traffic jam

Nakayama, Akihiro; Fukui, Minoru; Kikuchi, Macoto; Hasebe, Katsuya; Nishinari, Katsuhiro; Sugiyama, Yūki; Tadaki, Shin–ichi; Yukawa, Satoshi

doi:10.1088/1367-2630/11/8/083025

Cited by 60 publications

(38 citation statements)

References 14 publications

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“…The propagation velocity was determined to be 4.4 m/s (16 km/h) for the choice of τ = 1.5 s. The jam propagates in the opposite direction of the vehicle motion. These results are in approximate agreement with the observed values of Nagayama et al [8]. Small values of τ give no jam or much slower formation of the jam, which takes about 2 min for the full jam to emerge here.…”

Section: Simulationssupporting

confidence: 93%

“…Before jam emergence vehicle velocity-headway data remained close to the empirical characteristic line v = α(∆x − D) [8]. After the jam was fully formed, each vehicle moved with the same velocity curve as a function of time, but with a delay between successive vehicles.…”

Section: Discussionmentioning

confidence: 63%

“…The authors interpreted the empirical results as a collective phenomena-a non-equilibrium phase transition. Further discussion and additional analysis including individual driver characteristics were presented by Nakayama et al [8].…”

Section: Introductionmentioning

confidence: 99%

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Jam emergence on a circular track in a car-following model

Davis¹

2011

Physica A: Statistical Mechanics and its Applications

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Section: Simulationssupporting

confidence: 93%

Section: Discussionmentioning

confidence: 63%

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Jam emergence on a circular track in a car-following model

Davis¹

2011

Physica A: Statistical Mechanics and its Applications

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“…A similar experiment with cars was performed by Sugiyama et al [13,14] on a circular road with circumference C c = 230 m and N = 22 and 23, corresponding to global densities ρ g = 0.096 m −1 and 0.1 m −1 , respectively. Recently the same group improved these experiments [15].…”

Section: Methodsmentioning

confidence: 85%

Universal flow-density relation of single-file bicycle, pedestrian and car motion

et al. 2014

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The relation between flow and density is an essential quantitative characteristic to describe the efficiency of traffic systems. We have performed experiments with single-file motion of bicycles and compare the results with previous studies for car and pedestrian motion in similar setups. In the space-time diagrams we observe three different states of motion (free flow state, jammed state and stop-and-go waves) in all these systems. Despite of their obvious differences they are described by a universal fundamental diagram after proper rescaling of space and time which takes into account the size and free velocity of the three kinds of agents. This indicates that the similarities between the systems go deeper than expected.

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“…For this the already referenced data for pedestrians has been used, new data for cycling dynamics has been gathered and existing data from an experiment on vehicular dynamics [48,49] has been added. According to the description of measurement and (re-)evaluation here speed has been measured in exact accordance with the definition for quasi-instantaneous, spaceaveraged measurement.…”

Section: Comparison To Empirical Data Of Pedestrians Cyclists and Carsmentioning

confidence: 99%

The Inflection Point of the Speed-Density Relation and the Social Force Model

2016

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It has been argued that the speed-density diagram of pedestrian movement has an inflection point [1] (p. 3, "Domain I: ... At low densities there is a small and increasing decline of the velocity ... Domain III: ... For growing density the velocity remains nearly constant."). This inflection point was found empirically in investigations of closed-loop single-file pedestrian movement.The reduced complexity of single-file movement does not only allow a higher precision for the evaluation of empirical data, but it also significantly simplifies analytical considerations. This is especially true if one assumes homogeneous conditions, i.e. neglects temporal variations (consider time averages, neglect stop-and-go waves), individual differences of pedestrians (all simulated pedestrians have identical parameters) and investigates only steady-state (not the initial phase). As will be shown in this contribution one then can make a transition from the microscopic to a continuous and macroscopic perspective.Building on that it will be shown that certain (common) variants of the Social Force Model (SFM) do not produce an inflection point in the speed-density diagram if -assuming periodic boundary conditions -infinitely many pedestrians contribute to the force computed for one pedestrian. It will furthermore be shown that if -in said 1d movement situation -one only considers nearest neighbors for the computation of the interpedestrian forces the Social Force Model in the continuous description results in the so called Kladek formula for the speed-density relation. Since the Kladek formula exhibits the desired inflection point this observation is used as a motivation for an extension of the Social Force Model which allows to transform the continuous description of the SFM continuously to the Kladek formula and which also exhibits the inflection point in the speed density relation. It will be shown then, that this extended SFM yields astonishingly similar speed density relations as the original SFM when only a fixed limited number of (nearest) pedestrians are considered in the computation of the inter-pedestrian force. Finally it will be discussed, if also the description of the speed-density diagram for (motorized, four-wheel) vehicular and/or bicycle traffic could benefit from these measures.

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Metastability in the formation of an experimental traffic jam

Cited by 60 publications

References 14 publications

Jam emergence on a circular track in a car-following model

Jam emergence on a circular track in a car-following model

Universal flow-density relation of single-file bicycle, pedestrian and car motion

The Inflection Point of the Speed-Density Relation and the Social Force Model

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