A Stochastic Modeling of Traffic Breakdown for Freeway Merge Bottlenecks and Variable Speed Limit Control Strategies Using Connected Automated Vehicles PDF Download
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Author: Youngjun Han
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This thesis develops a novel breakdown probability model based on microscopic driver behavior for a freeway merge bottleneck. Extending Newell's car following model, two elements of breakdown, trigger and propagation, are derived in terms of vehicle headway. A general breakdown probability is derived in terms of various parameters related to driver behavior and traffic conditions that can be treated as constants or stochastic with probability distributions. The proposed model is validated with real data. It was found the theoretical breakdown probability distribution accords well with the empirical counterpart within reasonable ranges of parameter values. Developed model suggests the breakdown probability (i) increases with flow and the merging spacing, (ii) decreases with the merging speed and aggressive driver characteristics, and interestingly, (iii) increases with the deviation in headway. To achieve the optimum traffic state, the headway adjustment area is suggested as a proactive control with a combination of connected automated vehicle (CAV) and VMS. In this area, random headways evolve to more uniform headways without inducing controlled congestion propagating upstream. Reactive VSL control is also developed in this thesis. The CAV technology is applied to develop VSL strategies to improve bottleneck discharge rates and reduce system delays. Three reactive VSL control strategies are developed to enhance traffic stability using: (i) a single CAV (per lane) for control, (ii) a single CAV (per lane) coupled with VMS, and (iii) multiple CAVs. Adaptive schemes to complement the above three strategies are further developed. These VSL strategies using the CAV technology offer significant benefits over conventional control as: (i) they deliver more efficient control by creating a void, which is less restrictive and simpler; (ii) they could be more cost-effective; and (iii) CAVs can serve two key functions simultaneously, traffic monitoring and control action. This thesis formulates probabilistic control failure based on the stochastic traffic instability. This framework is developed based on the probability of instability by individual vehicles in different traffic states to obtain temporal evolution of probability of traffic instability and ensuing control failure. An optimal control speed is determined to maximize the expected delay saving incorporates probabilistic control failures over time.
Author: Youngjun Han
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This thesis develops a novel breakdown probability model based on microscopic driver behavior for a freeway merge bottleneck. Extending Newell's car following model, two elements of breakdown, trigger and propagation, are derived in terms of vehicle headway. A general breakdown probability is derived in terms of various parameters related to driver behavior and traffic conditions that can be treated as constants or stochastic with probability distributions. The proposed model is validated with real data. It was found the theoretical breakdown probability distribution accords well with the empirical counterpart within reasonable ranges of parameter values. Developed model suggests the breakdown probability (i) increases with flow and the merging spacing, (ii) decreases with the merging speed and aggressive driver characteristics, and interestingly, (iii) increases with the deviation in headway. To achieve the optimum traffic state, the headway adjustment area is suggested as a proactive control with a combination of connected automated vehicle (CAV) and VMS. In this area, random headways evolve to more uniform headways without inducing controlled congestion propagating upstream. Reactive VSL control is also developed in this thesis. The CAV technology is applied to develop VSL strategies to improve bottleneck discharge rates and reduce system delays. Three reactive VSL control strategies are developed to enhance traffic stability using: (i) a single CAV (per lane) for control, (ii) a single CAV (per lane) coupled with VMS, and (iii) multiple CAVs. Adaptive schemes to complement the above three strategies are further developed. These VSL strategies using the CAV technology offer significant benefits over conventional control as: (i) they deliver more efficient control by creating a void, which is less restrictive and simpler; (ii) they could be more cost-effective; and (iii) CAVs can serve two key functions simultaneously, traffic monitoring and control action. This thesis formulates probabilistic control failure based on the stochastic traffic instability. This framework is developed based on the probability of instability by individual vehicles in different traffic states to obtain temporal evolution of probability of traffic instability and ensuing control failure. An optimal control speed is determined to maximize the expected delay saving incorporates probabilistic control failures over time.
Author: Xiqun (Michael) Chen
Publisher: Springer
ISBN: 3662445727
Category : Technology & Engineering
Languages : en
Pages : 202
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Book Description
This book reveals the underlying mechanisms of complexity and stochastic evolutions of traffic flows. Using Eulerian and Lagrangian measurements, the authors propose lognormal headway/spacing/velocity distributions and subsequently develop a Markov car-following model to describe drivers’ random choices concerning headways/spacings, putting forward a stochastic fundamental diagram model for wide scattering flow-density points. In the context of highway onramp bottlenecks, the authors present a traffic flow breakdown probability model and spatial-temporal queuing model to improve the stability and reliability of road traffic flows. This book is intended for researchers and graduate students in the fields of transportation engineering and civil engineering.
Author: Md Hadiuzzaman
Publisher:
ISBN:
Category : Traffic congestion
Languages : en
Pages : 239
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Book Description
Over the past few decades, several active traffic control methods have been developed and implemented to mitigate freeway congestion. Among them, Variable Speed Limit (VSL) is considered the most efficient control method. In addition, the latest advances in Intelligent Transportation Systems (ITS) have made it feasible to implement predictive freeway control. The successful implementation of such control requires an accurate macroscopic traffic flow model that can predict all the important traffic dynamics. To avoid violation of the equilibrium traffic state assumption and to improve traffic state prediction accuracy in the VSL control situation, this research proposes a 2nd order model, DynaTAM-VSL, which drops parameterization of the METANET's FD; instead, it includes speed limit-dependent parameters in the speed and density dynamics. The validation results with the 20-s loop detector data confirmed that, compared to the existing models, the proposed model better simulates traffic flow. With the validated model, this research investigates the impact of control parameters and demand levels on total travel time and throughput under the coordinated VSL control and determined a range of the demand / bottleneck capacity ratio, when VSL simultaneously improves both of the mobility parameters, which resolved the existing paradoxical results. This research also proposes an isolated VSL control strategy that aims at avoiding capacity drop at recurrent freeway bottlenecks. To evaluate the effectiveness of the control strategy, a base model of the 11-km test site: Whitemud Drive (WMD), Edmonton is calibrated within a microscopic traffic flow simulator to reproduce real-world traffic conditions, while the control strategy is implemented to evaluate its impact. The sensitivity analysis of the control strategy on safety constraints and VSL update frequencies demonstrates promising results to support practical implementation. Considering its flexible use in macroscopic simulation, a 1st order traffic flow model, CTM-VSL, is proposed. Unlike the 2nd order models, it is parsimonious: it only includes parameters that can be estimated using routinely available point detector data. However, the model is valid only for the condition of perfect compliance by drivers to VSL control, since it shares same properties of the CTM model. To update the storage capacity of an upstream segment of a VSL sign, a real-time queue estimation model is proposed. Despite the simple structure of the CTM-VSL model, the VSL control shows comparable results with the DynaTAM-VSL in terms of improving mobility parameters. Finally, this research distinguishes the relative contributions of driver compliance levels (CLs) and a predictive VSL control with different CLs to improve traffic flows. Several CL-to-VSL strategies are modeled with a fixed co-efficient of variance of speeds obtained from static speed limit on WMD. The CLs include speed distributions for aggressive, compliant, and defensive drivers. It is proven that the mobility benefits from the VSL control are not at the expense of increased collision probability and vice-versa.
Author: Martin Treiber
Publisher: Springer Science & Business Media
ISBN: 3642324592
Category : Science
Languages : en
Pages : 505
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Book Description
This textbook provides a comprehensive and instructive coverage of vehicular traffic flow dynamics and modeling. It makes this fascinating interdisciplinary topic, which to date was only documented in parts by specialized monographs, accessible to a broad readership. Numerous figures and problems with solutions help the reader to quickly understand and practice the presented concepts. This book is targeted at students of physics and traffic engineering and, more generally, also at students and professionals in computer science, mathematics, and interdisciplinary topics. It also offers material for project work in programming and simulation at college and university level. The main part, after presenting different categories of traffic data, is devoted to a mathematical description of the dynamics of traffic flow, covering macroscopic models which describe traffic in terms of density, as well as microscopic many-particle models in which each particle corresponds to a vehicle and its driver. Focus chapters on traffic instabilities and model calibration/validation present these topics in a novel and systematic way. Finally, the theoretical framework is shown at work in selected applications such as traffic-state and travel-time estimation, intelligent transportation systems, traffic operations management, and a detailed physics-based model for fuel consumption and emissions.
Author: Moshe E. Ben-Akiva
Publisher:
ISBN:
Category : Automobile drivers
Languages : en
Pages : 3
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Book Description
Merging locations are major sources of freeway bottlenecks and are therefore important for freeway operations analysis. Microscopic simulation tools have been successfully used to analyze merging bottlenecks and to design optimum geometric configurations and control strategies for such locations. In congested situations, acceptable gaps for merging are often not available and freeway mainline drivers often cooperate with the on-ramp drivers and create gaps for the merge. This is usually done either by decelerating or by changing to an inner freeway lane. Also, in some cases the merging driver may become impatient and decide to force in, which compels the lag driver in the freeway to decelerate. The lane-changing and acceleration decisions of the freeway mainline driver are therefore not only based on his present situation, but also influenced by the anticipated intention of the merging driver (e.g. whether or not the merging driver is executing a forced merge). Consequently, the merging models developed for a particular freeway may not be applicable to other freeways.
Author: Boris S. Kerner
Publisher: Springer Science & Business Media
ISBN: 3642026052
Category : Technology & Engineering
Languages : en
Pages : 271
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Book Description
The understanding of empirical traf?c congestion occurring on unsignalized mul- lane highways and freeways is a key for effective traf?c management, control, or- nization, and other applications of transportation engineering. However, the traf?c ?ow theories and models that dominate up to now in transportation research journals and teaching programs of most universities cannot explain either traf?c breakdown or most features of the resulting congested patterns. These theories are also the - sis of most dynamic traf?c assignment models and freeway traf?c control methods, which therefore are not consistent with features of real traf?c. For this reason, the author introduced an alternative traf?c ?ow theory called three-phase traf?c theory, which can predict and explain the empirical spatiot- poral features of traf?c breakdown and the resulting traf?c congestion. A previous book “The Physics of Traf?c” (Springer, Berlin, 2004) presented a discussion of the empirical spatiotemporal features of congested traf?c patterns and of three-phase traf?c theory as well as their engineering applications. Rather than a comprehensive analysis of empirical and theoretical results in the ?eld, the present book includes no more empirical and theoretical results than are necessary for the understanding of vehicular traf?c on unsignalized multi-lane roads. The main objectives of the book are to present an “elementary” traf?c ?ow theory and control methods as well as to show links between three-phase traf?c t- ory and earlier traf?c ?ow theories. The need for such a book follows from many commentsofcolleaguesmadeafterpublicationofthebook“ThePhysicsofTraf?c”.
Author: Michael Behrisch
Publisher: Springer
ISBN: 3662450798
Category : Computers
Languages : en
Pages : 182
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Book Description
This book constitutes the thoroughly refereed proceedings of the First International Conference on Simulation of Urban Mobility, SUMO 2013, held in Berlin, Germany, in May 2013. The 12 revised full papers presented tin this book were carefully selected and reviewed from 22 submissions. The papers are organized in two topical sections: models and technical innovations and applications and surveys.
Author: Boris S. Kerner
Publisher: Springer
ISBN: 3540409866
Category : Science
Languages : en
Pages : 688
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Book Description
The core of ths book presents a theory developed by the author to combine the recent insight into empirical data with mathematical models in freeway traffic research based on dynamical non-linear processes.
Author: Nikolaos Bekiaris-Liberis
Publisher: SIAM
ISBN: 1611973171
Category : Mathematics
Languages : en
Pages : 293
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Book Description
The authors have developed a methodology for control of nonlinear systems in the presence of long delays, with large and rapid variation in the actuation or sensing path, or in the presence of long delays affecting the internal state of a system. In addition to control synthesis, they introduce tools to quantify the performance and the robustness properties of the designs provided in the book. The book is based on the concept of predictor feedback and infinite-dimensional backstepping transformation for linear systems and the authors guide the reader from the basic ideas of the concept?with constant delays only on the input?all the way through to nonlinear systems with state-dependent delays on the input as well as on system states. Readers will find the book useful because the authors provide elegant and systematic treatments of long-standing problems in delay systems, such as systems with state-dependent delays that arise in many applications. In addition, the authors give all control designs by explicit formulae, making the book especially useful for engineers who have faced delay-related challenges and are concerned with actual implementations and they accompany all control designs with Lyapunov-based analysis for establishing stability and performance guarantees.
Author: Hui Deng
Publisher:
ISBN: 9781339542522
Category :
Languages : en
Pages :
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Book Description
Individual driving behavior, such as anticipation, risk-taking and cooperative lane change, has significant impact on overall traffic flow characteristics and highway performance. It contributes to various traffic flow phenomena, including platooning, capacity drop and traffic oscillations. A good understanding of driving behavior under different driving environments, such as curved roads, lane-drops, merges and diverges, and platooning enabled by vehicle to vehicle communication, can help us design safer roads, and safer and more efficient autonomous or semi-autonomous driving vehicles. New car following models have been developed to capture the empirical observed anticipation and risk-taking driving behavior, and applied to investigate how anticipation and risk-taking may lead to different traffic flow phenomena and influence highway capacity and safety. Considering gap anticipation, full range traffic conditions can be reproduced, including free-flow, congestion and traffic jam under fixed and moving bottleneck, realistic flow capacities and fundamental diagrams with different levels of anticipation, as well as platoon driving when gap anticipation dependents on the gap. The effect of risk-taking on traffic safety is studied with a collision-possible car following model considering driver anticipation. Risk-taking leads to traffic oscillations and potential collision hazards when traffic is not stable. Longer length of view field can improve traffic safety, and large numbers of vehicle crashes happen when view field length is shorter than given threshold. Merge traffic dynamic has been studied by simulating of cooperative lane change, and drivers' merge location choice is studied to show its impact on traffic oscillations near merging junction. A simplified lane change cooperation strategy is developed and integrated with optimal speed car following logic to capture cooperative lane change behavior in merge junctions. This model can reproduce reasonable merge ratio, capacity drop, turn taking merging behavior and stop and go traffic at merge bottleneck. Lane change incentive and main lane traffic condition affect drivers' lane change behavior and leads to different merge location choice. Microscopic and macroscopic traffic simulation show merge location choice contributes to the formation of stop-and-go waves near merging junctions and the period of these waves are closely related to the distance between the two dominant merging locations. Theoretical and data analysis are used to reveal the correlation between drivers' anticipation, relaxation behavior and traffic hysteresis. Through an analysis of the trajectory data from NGSIM and a theoretical analysis of car-following models, it is revealed that traffic hysteresis is generated by an imbalance in driver relaxation and anticipation. By changing the strength of relaxation and anticipation, we are able to reproduce positive, negative and double hysteresis loops, as well as aggressive and timid driving behavior. It is further shown that the relative positions of acceleration and deceleration phase with respect to the equilibrium state is not unique and are determined by the comparative strength of relaxation and anticipation in different traffic conditions. This study suggests that traffic hysteresis can be suppressed by balancing driver relaxation and anticipation, and stop-and-go traffic can be smoothed by eliminating aggressive driving in congested traffic. A three-mode vehicle control law is proposed for ACC (Adaptive Cruise Control) and CACC (Cooperative Adaptive Cruise Control) and implemented in VENTOS (VEhicular NeTwork Open source Simulator). Traffic hysteresis and stability of studied both analytically and using VENTOS simulation. The ability of ACC/CACC to improve highway safety and eliminating traffic hysteresis is verified by traffic simulation under critical traffic conditions, including realistic stop-and-go traffic and worst case stopping. Through analytical approaches and simulation, we have demonstrated the stability and robustness of our proposed ACC/CACC control system against sensor measurement errors and lossy wireless communication links which is required to implement the CACC control logic. The benefit of wireless communication, even with some lossy links, is significant in ensuring stream stability and performance.
