Traffic congestion catastrophes

Navin, F

doi:10.1080/03081068608717327

Cited by 34 publications

(12 citation statements)

References 4 publications

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“…The jammed phase J contains traffic states characterized by a high density and small flow rate/flow speed values. Transitions are allowed between F and S, and between S and J, but not between F and J. Navin suggested the three-dimensional cusp catastrophe to be appropriate for traffic variables [12]. The surface of the cusp catastrophe is defined by two control variables with smooth continuous changes, whereas the state variable is subject to discontinuities.…”

Section: Discussionmentioning

confidence: 99%

A new kind of fundamental diagram with an application to road traffic emission modeling

Aguiléra

Tordeux

2013

J of Advced Transportation

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SUMMARYThe main contribution of this paper is to show, on the basis of empirical traffic data, that the distribution of vehicle speeds on a road segment evolves with the occupancy in a simple manner. Under a critical occupancy, the distribution is unimodal, with one peak (the high mode) close to the free-flow speed. When the occupancy exceeds the critical occupancy, the distribution of speeds becomes bimodal. A second peak (the low mode) appears, at a noticeably lower speed than the high mode. Empirical speed distributions are well fitted when assuming a (appropriately scaled and translated) low "temperature" Maxwell-Boltzmann distribution for the high mode and a high-temperature distribution for the low mode. The standard fundamental diagram expresses the mean flow speed as a function of occupancy. The model proposed in this paper expresses the distribution of vehicle speeds as a function of the occupancy. We believe this result to be of great importance for both the theory of traffic flow and practical applications.

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Section: Discussionmentioning

confidence: 99%

A new kind of fundamental diagram with an application to road traffic emission modeling

Aguiléra

Tordeux

2013

J of Advced Transportation

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“…A number of research efforts have concentrated on the relationship between speed, flow, and density and the sudden discrete changes that occur in the transition from uncongested to congested conditions. [See Pushkar, et al (1995), Hall and Lam (1988), Dillon and Hall (1988), Hall (1987), Hall and Gunter (1986), Navin (1986), and Dendrinos (1978).] These are discussed when the speed, flow, concentration relationship is presented in the following section on the Research Approach.…”

Section: Other Related Modelsmentioning

confidence: 99%

“…Catastrophe theory was used to attempt to explain the three-dimensional relationship among speed, concentration (occupancy), and flow. Specifically, it was used to explain the sudden discrete changes that occur for the speed variable, in this relationship while flow and occupancy exhibit a smooth and continuous change (Navin, 1986, Dendrinos, 1978, Hall, 1987, Dillon and Hall, 1987, Hall and Lam, 1988. Since, according to equation 3, the variable F/O can be considered to vary monotonically with speed, (assuming traffic composition and other conditions are fairly stable along the freeway section for each time interval) then it can serve as a surrogate variable for speed and the discrete changes from uncongested to congested conditions can be better observed with this variable.…”

Section: F/o Ratio As a Congestion Indicatormentioning

confidence: 99%

Evaluation of forced flows on freeways with single‐loop detectors

Nihan

2000

J of Advced Transportation

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This paper documents the development of a simple method for identifying andor predicting freeway congestion using single loop detection systems. The proposed algorithm is simple and easy to incorporate into most freeway management systems. The Washington State Department of Transportation's Traffic Systems Management Center (TSMC) sponsored the original study. The investigation also led to a recommendation to replace the original TSMC definition of congestion or forced flow conditions with a more reliable indicator.Although, the TSMC has recently implemented a more advanced prediction system based on fuzzy set theory and neural networks to further identify patterns and rules for ramp metering strategies, the findings presented here continue to be constructive to freeway managers looking for quick and easy analyses that rely solely on single-loop detection systems.The Seattle Area freeway study section used for the original study was the portion of mainline 1-5 northbound starting at the downtown Seattle Station 108 and ending at the Mountlake Terrace Station 193. Several days' worth of volume and lane-occupancy data were collected for the afternoon time period from 2:30 p.m. to 6:30 p.m.. Time intervals of 20 seconds were chosen for each data collection period.Important products of this research include the following: A simple, and more reliable criterion for the definition of "bottleneck" or forced flow conditions than that originally used by the TSMC.A simple, and reliable criterion for predicting impending "bottlenecks" or forced flow conditions.A proposed variable for improved selection of the appropriate metering rate. (Further analysis of the use of this variable for determining metering rates is recommended for future studies.) The proposed criteria are simple and easy to incorporate into current freeway management computer systems. Further investigation of freeway performance measurement using volume and occupancy data obtained from single-loop systems is currently being performed.

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“…They also presented an empirical explanation for the inverted V shape to be observed on the basis of the catastrophe theory. 12,13 But it is still not clear if their conclusion is justified. As will be shown below, our computer simulation suggests that reversed lambda shape is more suitable rather than inverted V shape.…”

Section: Introductionmentioning

confidence: 97%

Complexity in a Critical Traffic Flow

Yukawa

Kikuchi

2000

Int. J. Mod. Phys. C

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The traffic flow near the jamming transition is numerically studied by computer simulations of a coupled-map model. Just above the transition, a variety of velocities with which the traffic jams propagate are observed. The entropy of the traffic flow becomes maximum at the same time. Moreover, the current-concentration relation obtained by local measurements shows clear double-valued behavior near the critical concentration. From these properties, the traffic flow can be said as maximally complex near the critical concentration.

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Traffic congestion catastrophes

Cited by 34 publications

References 4 publications

A new kind of fundamental diagram with an application to road traffic emission modeling

A new kind of fundamental diagram with an application to road traffic emission modeling

Evaluation of forced flows on freeways with single‐loop detectors

Complexity in a Critical Traffic Flow

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