The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Markos Papageorgiou - One of the best experts on this subject based on the ideXlab platform.
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traffic flow optimisation in presence of vehicle automation and communication systems part i a first order multi lane model for Motorway traffic
Transportation Research Part C-emerging Technologies, 2015Co-Authors: Claudio Roncoli, Markos Papageorgiou, Ioannis PapamichailAbstract:Proposed or emerging vehicle automation and communication systems (VACS) may contribute to the mitigation of Motorway traffic congestion on the basis of appropriate traffic control strategies. In this context, this paper presents a novel first-order multi-lane macroscopic traffic flow model for Motorways which is mainly intended for use within a related optimal control problem formulation. The model’s starting point is close to the well-known CTM (cell-transmission model), which is modified and extended to consider additional aspects of the traffic dynamics, such as lane changing and the capacity drop, via appropriate procedures for computing lateral and longitudinal flows. The model has been derived with a view to combine realistic traffic flow description with a simple (linear or piecewise linear) mathematical form, which can be exploited for efficient optimal control problem formulations, as described in a companion (Part II) paper. Although the model has been primarily derived for use in future traffic conditions including VACS, it may also be used for conventional traffic flow representation. In fact, the accuracy of the proposed modelling approach is demonstrated through calibration and validation procedures using real data from an urban Motorway located in Melbourne, Australia.
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optimal Motorway traffic flow control involving variable speed limits and ramp metering
Transportation Science, 2010Co-Authors: Rodrigo Castelan Carlson, Ioannis Papamichail, Markos Papageorgiou, Albert MessmerAbstract:The impact of variable speed limits (VSL) on aggregate traffic flow behaviour on Motorways is shown to bear similarities to the impact of ramp metering, in particular, when addressing potentially active bottlenecks. A quantitative model of the VSL impact is proposed that allows for VSL to be incorporated in a macroscopic second-order traffic flow model as an additional control component. The integrated Motorway network traffic control problem involving ramp metering and VSL control measures is formulated as a constrained discrete-time optimal control problem and is solved efficiently even for large-scale networks by a suitable feasible direction algorithm. An illustrative example of a hypothetical Motorway stretch is investigated under different control scenarios, and it is shown that traffic flow efficiency can be substantially improved when VSL control measures are used, particularly in integration with coordinated ramp metering.
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Effects of Variable Speed Limits on Motorway Traffic Flow
Transportation Research Board, 2008Co-Authors: Markos Papageorgiou, Elias Kosmatopoulos, Ioannis PapamichailAbstract:Variable speed limits (VSLs) displayed on roadside variable message signs (VMSs) have emerged as a widespread traffic control measure on Motorways in many countries, leading to substantial traffic safety benefits; however, there is no clear evidence of improved traffic flow efficiency in operational VSL systems. The available information on VSL impact on aggregate traffic flow behavior is summarized, and the issue is investigated in more detail with real traffic data from a European Motorway. It is found that VSLs decrease the slope of the flow-occupancy diagram at undercritical conditions, shift the critical occupancy to higher values, and enable higher flows at the same occupancy values in overcritical conditions. Implications of the derived findings for more efficient VSL control strategies are discussed.
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The importance of traffic flow modeling for Motorway traffic control
Networks and Spatial Economics, 2001Co-Authors: Markos PapageorgiouAbstract:The problem of traffic congestion in modern day Motorways calls for the design and implementation of efficient control strategies. It is argued in this paper that in order to have efficient, generic, and systematic solutions to a wide range of traffic control problems, macroscopic Motorway traffic flow models in state-space form, that are relevant for the control problem and computationally non-intensive, are most appropriate. Such models allow the exploitation of available powerful, systematic, and theoretically supported automatic control concepts. Based on these concepts an Extended Kalman Filter for traffic state estimation, a multivariable LQI controller for coordinated ramp metering on a Motorway stretch, and an integrated optimal control strategy for Motorway networks are shortly presented. The criteria of a model's relevance for a given traffic control problem and its computational requirements are subsequently examined. Finally, the application of an advanced coordinated ramp metering control strategy, based on the optimal control approach, to the ring-road of Amsterdam, The Netherlands, is provided as an illustrative example.
Ioannis Papamichail - One of the best experts on this subject based on the ideXlab platform.
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traffic flow optimisation in presence of vehicle automation and communication systems part i a first order multi lane model for Motorway traffic
Transportation Research Part C-emerging Technologies, 2015Co-Authors: Claudio Roncoli, Markos Papageorgiou, Ioannis PapamichailAbstract:Proposed or emerging vehicle automation and communication systems (VACS) may contribute to the mitigation of Motorway traffic congestion on the basis of appropriate traffic control strategies. In this context, this paper presents a novel first-order multi-lane macroscopic traffic flow model for Motorways which is mainly intended for use within a related optimal control problem formulation. The model’s starting point is close to the well-known CTM (cell-transmission model), which is modified and extended to consider additional aspects of the traffic dynamics, such as lane changing and the capacity drop, via appropriate procedures for computing lateral and longitudinal flows. The model has been derived with a view to combine realistic traffic flow description with a simple (linear or piecewise linear) mathematical form, which can be exploited for efficient optimal control problem formulations, as described in a companion (Part II) paper. Although the model has been primarily derived for use in future traffic conditions including VACS, it may also be used for conventional traffic flow representation. In fact, the accuracy of the proposed modelling approach is demonstrated through calibration and validation procedures using real data from an urban Motorway located in Melbourne, Australia.
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optimal Motorway traffic flow control involving variable speed limits and ramp metering
Transportation Science, 2010Co-Authors: Rodrigo Castelan Carlson, Ioannis Papamichail, Markos Papageorgiou, Albert MessmerAbstract:The impact of variable speed limits (VSL) on aggregate traffic flow behaviour on Motorways is shown to bear similarities to the impact of ramp metering, in particular, when addressing potentially active bottlenecks. A quantitative model of the VSL impact is proposed that allows for VSL to be incorporated in a macroscopic second-order traffic flow model as an additional control component. The integrated Motorway network traffic control problem involving ramp metering and VSL control measures is formulated as a constrained discrete-time optimal control problem and is solved efficiently even for large-scale networks by a suitable feasible direction algorithm. An illustrative example of a hypothetical Motorway stretch is investigated under different control scenarios, and it is shown that traffic flow efficiency can be substantially improved when VSL control measures are used, particularly in integration with coordinated ramp metering.
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Effects of Variable Speed Limits on Motorway Traffic Flow
Transportation Research Board, 2008Co-Authors: Markos Papageorgiou, Elias Kosmatopoulos, Ioannis PapamichailAbstract:Variable speed limits (VSLs) displayed on roadside variable message signs (VMSs) have emerged as a widespread traffic control measure on Motorways in many countries, leading to substantial traffic safety benefits; however, there is no clear evidence of improved traffic flow efficiency in operational VSL systems. The available information on VSL impact on aggregate traffic flow behavior is summarized, and the issue is investigated in more detail with real traffic data from a European Motorway. It is found that VSLs decrease the slope of the flow-occupancy diagram at undercritical conditions, shift the critical occupancy to higher values, and enable higher flows at the same occupancy values in overcritical conditions. Implications of the derived findings for more efficient VSL control strategies are discussed.
Albert Messmer - One of the best experts on this subject based on the ideXlab platform.
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optimal Motorway traffic flow control involving variable speed limits and ramp metering
Transportation Science, 2010Co-Authors: Rodrigo Castelan Carlson, Ioannis Papamichail, Markos Papageorgiou, Albert MessmerAbstract:The impact of variable speed limits (VSL) on aggregate traffic flow behaviour on Motorways is shown to bear similarities to the impact of ramp metering, in particular, when addressing potentially active bottlenecks. A quantitative model of the VSL impact is proposed that allows for VSL to be incorporated in a macroscopic second-order traffic flow model as an additional control component. The integrated Motorway network traffic control problem involving ramp metering and VSL control measures is formulated as a constrained discrete-time optimal control problem and is solved efficiently even for large-scale networks by a suitable feasible direction algorithm. An illustrative example of a hypothetical Motorway stretch is investigated under different control scenarios, and it is shown that traffic flow efficiency can be substantially improved when VSL control measures are used, particularly in integration with coordinated ramp metering.
Susanne Berns - One of the best experts on this subject based on the ideXlab platform.
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TRAFFIC SAFETY ON MotorwayS
Iatss Research, 1995Co-Authors: Ekkehard Bruhning, Susanne BernsAbstract:The German Motorway network with a length exceeding 11,000 km accounts for more than one quarter of the total kilometrage recorded in Germany. Although Motorways are the safest roads, autobahn safety is the focus of interest. An overview is given on Motorway safety at the international level with special aspects highlighted.
Karel Brookhuis - One of the best experts on this subject based on the ideXlab platform.
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merging into heavy Motorway traffic by young and elderly drivers
Accident Analysis & Prevention, 2009Co-Authors: Dick De Waard, Chris Dijksterhuis, Karel BrookhuisAbstract:An increase in the number of Heavy Goods Vehicles on Motorways may lead to additional problems in the interaction with an increased number of elderly drivers. Elderly drivers suffer from reduced information processing speed and capacity, and in general effectively compensate for this by taking more time. However, this strategy, regulating task demands by slowing down will make merging into Motorway traffic actually more difficult. In an experiment performed in a driving simulator, young and elderly drivers merged into Motorway traffic. Driver behaviour and mental workload were studied while the following factors were manipulated: type of traffic and density of Heavy Goods Vehicles on the main road, the length of the acceleration lane, presence of a slowly driving lead car, and presence of a driver support system that encouraged the drivers to speed up if their speed was too low. Results show that the effects of an increased number of Heavy Goods Vehicles on the main road were not more adverse for elderly than for the young participants, with the exception that elderly drivers merged at a lower speed. This lower speed could make the manoeuvre more risky in real traffic. The support system and an extended acceleration lane facilitated merging, while a slowly driving lead car impeded completion of the manoeuvre.
