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Traffic wave

About: Traffic wave is a research topic. Over the lifetime, 2106 publications have been published within this topic receiving 62117 citations. The topic is also known as: phantom traffic jam & ghost jams.


Papers
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Journal ArticleDOI
TL;DR: The study results indicate that the mean queue-discharge rates in Indiana freeway work zones were lower than the work zone capacities, and it is not justified to use work zone capacity values, instead of queue- discharge rates, in estimating traffic delays and user costs under congested conditions.
Abstract: In addition to traffic capacity, vehicle speeds and queue-discharge rates at work zones are essential in assessment of work zone traffic delays and user costs. The traffic flow characteristics of freeway work zones were analyzed based on the traffic data collected from Indiana four-lane freeways. It was found that traffic congestion at work zones was characterized by sustained low vehicle speeds and fluctuating traffic flow rates. Therefore, work zone capacity was defined as the traffic flow rate just before a sharp speed drop, followed by a sustained period of low vehicle speed and fluctuating traffic flow rate. Study results indicate that the mean queue-discharge rates in Indiana freeway work zones were lower than the work zone capacities, even though, at times, individual values of queue-discharge rates could be higher than capacities. Therefore, it is not justified to use work zone capacity values, instead of queue-discharge rates, in estimating traffic delays and user costs under congested conditions...

106 citations

Journal ArticleDOI
TL;DR: It is shown that traffic flow stability will be preserved for an open stretch highway if the entry and exit conditions are made to observe the downstream biasing strategy, and that traffic dynamics will be qualitatively consistent across the three modeling paradigms.
Abstract: This paper is concerned with the traffic flow stability/instability induced by a particular adaptive cruise control (ACC) policy, known as the “constant time headway (CTH) policy”. The control policy is analyzed for a circular highway using three different traffic models, namely a microscopic model, a spatially discrete model, and a spatially continuous model. It is shown that these three different modeling paradigms can result in different traffic stability properties unless the control policy and traffic dynamics are consistently abstracted for the different paradigms. The traffic dynamics will, however, be qualitatively consistent across the three modeling paradigms if a consistent biasing strategy is used to adapt the CTH policy to the various modeling frameworks. The biasing strategy determines whether the feedback quantity for use in the control, is taken colocatedly, downstream or upstream to the vehicle/section/highway location. For ACC vehicles equipped with forward looking sensors, the downstream biasing strategy should be used. In this case, the CTH policy induces exponentially stable traffic flow on a circular highway in all three modeling frameworks. It is also shown that traffic flow stability will be preserved for an open stretch highway if the entry and exit conditions are made to observe the downstream biasing strategy.

104 citations

Proceedings ArticleDOI
25 Aug 2001
TL;DR: In this article, the authors studied traffic data from a section of southbound highway 101- a heavily commuted eight-lane freeway between San Francisco and the Silicon valley in California and observed two parameters that drivers regulate during free flow, rush hour, and heavy traffic conditions: (1) the speed of their vehicle; and (2) the time-headway to the preceding vehicle.
Abstract: The preferred time-headway of drivers in highway conditions is related to the likelihood of rear-end collisions. We studied traffic data from a section of southbound highway 101- a heavily commuted eight-lane freeway between San Francisco and the Silicon valley in California. We observed two parameters that drivers regulate during free flow, rush hour, and heavy traffic conditions: (1) the speed of their vehicle; and (2) the time-headway to the preceding vehicle. During free flow traffic, the preferred speeds show low variation within lanes, but large variations from lane to lane. During rush hour traffic, the time-headway between vehicles varies between 1 and 2 s for a range of traffic speeds. For all traffic conditions a lower limit of 1s is seen in time-headway, even when traffic volume does not push drivers toward tight spacing. The lower limit of 1s is consistent with what was found in several previous studies, but is significantly shorter than the 3s headway that is recommended by driving manuals. The short time-headways observed are within the limit of typical reaction time for braking by alert drivers, but probably lead to occasional accidents given variability in reaction times, decisions, and vehicle braking capabilities, especially when preview information is not available.

104 citations

Book
23 Jan 2009
TL;DR: In this article, the main scientific and engineering goal of this book is to deal simultaneously with soil dynamics/vibrations and wave propagation in soils (including seismic waves), and the important links between them, both from scientific and practical points of view, are unfortunately not investigated.
Abstract: The main scientific and engineering goal of this book is to deal simultaneously with soil dynamics/vibrations and wave propagation in soils (including seismic waves). These various fields are generally considered separately and the important links between them, both from scientific and practical points of view, are unfortunately not investigated. They are usually considered in separate disciplines such as earthquake geotechnical engineering, civil engineering, mechanics, geophysics, seismology, numerical modelling, etc. The objective of the book is to offer in a single publication an overview of soil dynamics and wave propagation in soils with emphasis on engineering applications. It starts from a wide variety of practical problems (e.g. traffic induced vibrations, dynamic compaction, vibration isolation), then deals with 1D and 2D/3D wave propagation in heterogeneous and attenuating media (with application to laboratory and in situ dynamic characterization of soils), gives an overview of various numerical methods (e.g. FEM, BEM) to simulate wave propagation (including numerical errors, radiation/absorbing conditions, etc) and finally investigates seismic wave propagation and amplification in complex geological structures (e.g. irregular topographies, alluvial deposits).

104 citations

Journal ArticleDOI
TL;DR: In this paper, the authors have carried out a large scale experiment to study the car-following behavior in a 51-car platoon and found that there exists a critical speed between 30 and 40 km/h, above which the standard deviation of car velocity is almost saturated (flat) along the platoon.
Abstract: Traffic instability is an important but undesirable feature of traffic flow. This paper reports our experimental and empirical studies on traffic flow instability. We have carried out a large scale experiment to study the car-following behavior in a 51-car-platoon. The experiment has reproduced the phenomena and confirmed the findings in our previous 25-car-platoon experiment, i.e., standard deviation of vehicle speeds increases in a concave way along the platoon. Based on our experimental results, we argue that traffic speed rather than vehicle spacing (or density) might be a better indicator of traffic instability, because vehicles can have different spacing under the same speed. For these drivers, there exists a critical speed between 30 km/h and 40 km/h, above which the standard deviation of car velocity is almost saturated (flat) along the 51-car-platoon, indicating that the traffic flow is likely to be stable. In contrast, below this critical speed, traffic flow is unstable and can lead to the formation of traffic jams. Traffic data from the Nanjing Airport Highway support the experimental observation of existence of a critical speed. Based on these findings, we propose an alternative mechanism of traffic instability: the competition between stochastic factors and the so-called speed adaptation effect, which can better explain the concave growth of speed standard deviation in traffic flow.

103 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202314
202237
202120
202017
201919
201822