Showing papers on "Traffic wave published in 1997"
TL;DR: In this paper, the authors design, analyze and simulate a roadway controller for an automated highway system (AHS) that achieved desired traffic densities along the freeway lane.
81 citations
TL;DR: In this article, an analytical theory of traffic jam of large amplitude is developed based on singular perturbation methods, which leads to analytical formulas for the characteristic parameters of traffic flow that are independent of road length, vehicle density, or other initial conditions.
Abstract: Based on singular perturbation methods, an asymptotic theory of traffic jams of large amplitude is developed in this work. Simple equations describing the form of traffic jams of large amplitude are found. The theory leads to analytical formulas for the characteristic parameters of traffic flow that are independent of road length, vehicle density of the initial traffic flow, or other initial conditions. Analytical investigations have been made showing that, in agreement with earlier numerical results (Kerner and Konhauser, 1994), the boundary flux at which a traffic jam can still exist is equal to the flux in the flow from a jam. The manner in which the shape of a traffic jam evolves due to changes in initial vehicle density is analytically studied. Simple analytical formulas are obtained for parameters of narrow traffic jams capable of forming in a limited interval of vehicle densities. A comparison is also made between results of the present analytical theory of traffic jams, the theory of shock waves in gas dynamics, the classical Lighthill-Whitham theory of kinematic waves (1955), and the recently discovered experimental features and characteristics of wide traffic jams in traffic.
70 citations
01 Dec 1997
TL;DR: The authors extend some of the existing CA models to capture characteristics of traffic flow that have not been possible to model using either conventional analytical models or existing simulation techniques to explore the usefulness of cellular automata to traffic flow modeling.
Abstract: This paper explores the usefulness of cellular automata (CA) to traffic flow modeling. The authors extend some of the existing CA models to capture characteristics of traffic flow that have not been possible to model using either conventional analytical models or existing simulation techniques. In particular, they examine higher moments of traffic flow and evaluate their effect on overall traffic performance. The behavior of these higher moments is found to be surprising, somewhat counter-intuitive, and to have important implications for design and control of traffic systems. For example, the authors show that the density of maximum throughput is near the density of maximum speed variance. Contrary to current practice, traffic should, therefore, be steered away from this density region. For deterministic systems they found traffic flow to possess a finite period which is highly sensitive to density in a non-monotonic fashion. They show that knowledge of this periodic behavior is very useful in designing and controlling automated systems. These results are obtained for both single and two lane systems. For two lane systems, they also examine the relationship between lane changing behavior and flow performance. They show that the density of maximum lane changing frequency occurs past the density of maximum throughput. Therefore, traffic should also be steered away from this density region.
34 citations
01 Jan 1997
TL;DR: Whether making a lane available for 'intelligent' vehicles can increase the capacity of a bottleneck in the motorway network using the MICroscopic model for Simulation of Intelligent Cruise control (MIXIC) 1.3 is examined.
Abstract: Intelligent Cruise Control (ICC) is an in-car system that automatically maintains a specified speed, taking into account a minimal distance with respect to predecessors. This paper presents the results of a simulation study on the effects of a special lane for ICC vehicles on traffic flow on motorways. The microscopic traffic simulation model MIXIC was used to evaluate the traffic performance and traffic safety. Simulation results demonstrate that the introduction of a dedicated lane for ICC vehicles in the situation of lane drops can improve the traffic flow stability and the traffic throughput. For the covering abstract, see IRRD 490001.
27 citations
31 Oct 1997
TL;DR: Differences in car-following between congested and non-congested flow are analyzed with data from two sites on Dutch freeways and Macroscopic distance gap - speed models are established for several road user classes, valid for each of the two flow regimes.
Abstract: In traffic flow analysis several regimes are distinguished, such as congested and non-congested flow conditions. Indications exist that driving behavior differs by regime, and that it may change discontinuously between regimes. In contrast, most traffic flow models used today basically assume the same car-following behavior irrespective of the traffic flow regime. It is hypothesized that because of this deficiency, these models do not always perform satisfactorily. To clarify this issue, differences in car-following between congested and non-congested flow are analyzed with data from two sites on Dutch freeways. It is shown that, at the same speeds, passenger car drivers follow with smaller headways in non-congested flow than in congested flow. Car-following of truck drivers does not show differences between regimes. Microscopic distance gap - speed models are established for several road user classes, valid for each of the two flow regimes. To show the improvements resulting from these new microscopic relationships, the latter are implemented in a micro simulation model (FOSIM) with which macroscopic patterns in traffic flow are modeled. The macroscopic findings produced with the regime specific car-following rules show a considerable improvement in modeling performance.
26 citations
Posted Content•
TL;DR: In this article, the authors presented microscopic time-space diagrams for several shock waves over 100-200m distances, and the primary focus of the paper was on presenting the data rather than analysis.
Abstract: This paper presents microscopic time-space diagrams for several shock waves over 100-200m distances. The primary focus of the paper is on presenting the data rather than analysis. The diagrams should be of general interest to researchers studying traffic congestion.
18 citations
17 citations
TL;DR: The Biham-Middleton-Levine model is improved by removing its limitation of synchronized change of traffic lights and in new model, the traffic light at each crossing could arbitrarily change its starting time and tempo of variation and hence the model could more realistically describe the influence of traffic Lights on the performance of traffic systems.
14 citations
TL;DR: A distributed, knowledge-based system for real-time, traffic-adaptive control of traffic signals that optimizes the control of steady-state traffic at a single intersection and over a network of streets and deals with predictive/reactive control in responding to sudden changes in traffic patterns.
7 citations
Journal Article•
TL;DR: The paper presents the theory of the model and the first results from simulation using the newly-developed STRADA-I program for incident scenario modelling in mixed urban networks.
Abstract: Traffic incidents contribute to urban network congestion by creating an impact on traffic which can be surprisingly fast and may involve rapid spilling-back congestion. In traffic science, traffic incidents are seldom considered from the point of view of the local perturbation of the traffic dynamic which they induce, but rather as a source of non-recurrent congestion disrupting the usual vehicle routes in the network. In consequence, urban network modelling tools, when used to simulate incidents, put emphasis on the impact of incidents on the traffic assignment and simplistically model their impact on the flow dynamics. However, the traffic flow and the assignment sub-models are inter-related in the sense that the link travel times output from the flow sub-model are a basic criterion for the assignment process, which in turn outputs traffic volumes to be propagated along links and may thus modify the previously-established link travel times. It therefore appears that an accurate modelling of the flow dynamics perturbation induced by an incident at the local link level is crucial for the modelling of the impact of the incident at the network level. In particular, the existing variety of incidents implies more than a representation involving a temporary reduction in capacity. Also, it should be possible to model the incident extent and position in a link, rather than assimilating the incident location to either a network point or a whole link length. A discretised version of a first-order macroscopic model allowing for an accurate representation of incidents precisely enables a flow dynamics perturbation evolution through space and time to be simulated. The paper presents the theory of the model and the first results from simulation using the newly-developed STRADA-I program for incident scenario modelling in mixed urban networks. (A)
01 Oct 1997
TL;DR: In this article, it was shown that all phase transitions in and out of freely flowing traffic reported earlier for a German site could be caused by bottlenecks, as are all the transitions observed at two other sites examined here.
Abstract: It is shown that all the phase transitions in and out of freely flowing traffic reported earlier for a German site could be caused by bottlenecks, as are all the transitions observed at two other sites examined here. Furthermore, all the evidence indicates that bottlenecks cause these transitions in a predictable way, and no evidence is found that stoppages (jams) appear spontaneously in free flow traffic for no apparent reason. The most salient phenomena observed at all locations are explained in terms of a simple theory specific to traffic.
TL;DR: The presented macroscopic simulation of the traffic flow on a multilane test stretch with a bottleneck displays the significant effects of a speed limit reduction inside the bottleneck region on the formation and propagation of traffic jams.
17 Dec 1997
TL;DR: The time and space dynamics of a mobile subscriber highway system is investigated and the parameters such as calling and noncalling vehicle density, offered traffic load and blocking probability are calculated, assuming different vehicle's velocity patterns.
Abstract: The deterministic fluid model is used to investigate the behaviour of the mobile along the highway. This paper presents the simulation of a mobile traffic on a one way semi-infinite highway, with multiple entrances and exits, based on a time non-homogeneous model. The system is described with ordinary differential equations, which are solved numerically. The parameters such as calling and noncalling vehicle density, offered traffic load and blocking probability are calculated, assuming different vehicle's velocity patterns. The time and space dynamics of a mobile subscriber highway system is investigated.
03 May 1997
TL;DR: A large potential is indicated to provide fast, secure and fault-tolerant transmission for highly bursty traffic sources as well as from the network’s point of view.
Abstract: Traffic dispersion means spreading the traffic from a source over multiple independent paths, transmitting it in parallel through the network. The strategy reduces the effects of bursts in the traffic, and may hence improve the network performance in terms of reduced queuing delay. So far, there have been several reports on traffic dispersion, but to our best knowledge, there has been no in-depth investigation of how the strategy affects different types of traffic under various conditions. This paper focuses on the basic properties of traffic dispersion by defining the strategy and investigating it from the source’s as well as from the network’s point of view. We investigate the influence of dispersion on Poisson traffic, traffic generated by two-state Markov chains and traffic generated by the chaotic FPDI-map. The results indicate a large potential of traffic dispersion to provide fast, secure and fault-tolerant transmission for highly bursty traffic sources.
01 Jan 1997
TL;DR: This study focused on the simulation of the Interstate 4 Central Corridor for the application with the Management Information System for Transportation, identifying a suitable simulation package to be used and details the calibration efforts and the factors that were adjusted to fit the model to the observed conditions on the freeway.
01 Jan 1997
TL;DR: This model, aimed at the non-recurrent change of traffic flow, the constraint of travel speed is introduced into the model and can be used not only to prevent traffic jams but also to control a slight jam.
Abstract: In order to develop an intelligent control and management system for urban expressway, this study proposes the dynamic inflow control method and model. In this model, the time-dependent changes in both the inflow demand and the traffic condition on the network and the driver's route choice behavior are explicitly considered. Aimed at the non-recurrent change of traffic flow, the constraint of travel speed is introduced into the model. As a result, this inflow control model can be used not only to prevent traffic jams but also to control a slight jam. This study analyzes the basic characteristics of dynamic control method through simple numerical experiments. For the covering abstract, see IRRD 490001.
TL;DR: The VEDENS computer code models traffic flows on unidirectional, multilane highways, including on- and off-ramps, concluding that the efficiency of a highway decreases significantly when the number of lanes is increased to more than four.
Abstract: The VEDENS computer code models traffic flows on unidirectional, multilane highways, including on- and off-ramps. The logic behind the code is explained, including driver decision making. Calculations have been carried out for from 1- to 6-lane flow. The fundamental flow diagram has been plotted for all lane configurations and calculations of saturation behaviour have been made for on-ramp and off-ramp flows and short-term, total blockages. It is concluded that the efficiency of a highway decreases significantly when the number of lanes is increased to more than four. Increasing the number of lanes is beneficial for on-ramp flows, but increasing the number to more than three has no effect on the maximum capacity when 20% or more of the vehicles desire to exit via a given off-ramp. When the highway becomes totally blocked for a short time, the evolution of the node of stationary traffic can be predicted.
TL;DR: Familiarity, ease of access, trust, and awareness of risks and benefits will all be important.
Abstract: 本研究は, 交通制御支援システムの一部として, 混雑した道路ネットワークにおける将来の交通流状況を適確に予測しうる動的トラフィック・シミュレーション手法を提示するものである. 交通流モデルとして連続流体モデルを用いており, 交通流中の衝撃波を考慮することにより, 渋滞の形成や, 延伸・減衰を適確に表現することを可能とした. 実用性の観点から, モデルをできるだけシンプルにするとともに, 並列的な演算が可能となるようモデル化を行なっている. またネットワーク上でのシミュレーションを行なうために, フローのOD構成の表現方法や, 合流・分流に対する取り扱い, 経路選択について考慮している. 2, 3の簡単なシミュレーション例を用いて, 交通流の動的な挙動の再現性について考察を行なった.
TL;DR: In this paper, the authors describe a scenario in which a vehicle is sent to a station with a driver and a driver, and the driver is asked to drive the vehicle to the station.
Abstract: 複数車線上の交通密度分布の時間経過に伴う特性を波動理論を用い分析する. 合流の際の車線移行を加味した交通流の連続式を導き, 生じる衝撃波の特性を検討する. 分岐車線等からの渋滞が直進車を妨げる状況を移動ボトルネックとして捕らえ, 交通流の連続式を用い, 車線移行により発生する渋滞の特性を明らかにする. これらの分析に加え, 分岐, 車線選択挙動をモデル化している. これら分析, モデル化により, 疑似衝撃波の概念を用いたシミュレーションモデルで信号交差点を含み複数車線で構成される道路ネットワーク上の交通密度分析を可能とした.