Evaluating Ramp Metering And Variable Speed Limits To Reduce Crash Potential On Congested Freeways Using Micro Simulation
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Efficient Transportation And Pavement Systems Characterization Mechanisms Simulation And Modeling
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Author : Imad L. Al-Qadi
language : en
Publisher: CRC Press
Release Date : 2008-11-01
Efficient Transportation And Pavement Systems Characterization Mechanisms Simulation And Modeling written by Imad L. Al-Qadi and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008-11-01 with Technology & Engineering categories.
Internationally, significant attention is given to transport sustainability, including planning, design, construction, evaluation, safety, and durability of the road system. The 4th International Gulf Conference on Roads: Efficient Transportation and Pavement Systems - Characterization, Mechanisms, Simulation, and Modeling, hosted by the University of Qatar, provided a forum for discussions of recent developments and research results and needs on transportation network optimization, traffic management, transportation safety, and pavement design, analysis, material characterization, modeling, and rehabilitation techniques. This book is a collection of 79 fully refereed papers and six keynote lectures.
Evaluating Ramp Metering And Variable Speed Limits To Reduce Crash Potential On Congested Freeways Using Micro Simulation
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Author : Albinder Singh Dhindsa
language : en
Publisher:
Release Date : 2005
Evaluating Ramp Metering And Variable Speed Limits To Reduce Crash Potential On Congested Freeways Using Micro Simulation written by Albinder Singh Dhindsa and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Adaptive control systems categories.
Recent research at UCF into defining surrogate measures for identifying crash prone conditions on freeways has led to the introduction of several statistical models which can flag such conditions with a good degree of accuracy. Outputs from these models have the potential to be used as real-time safety measures on freeways. They may also act as the basis for the evaluation of several intervention strategies that might help in the mitigation of risk of crashes.
Proceedings Of The Conference Of The Hong Kong Society For Transportation Studies
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Author : Hong Kong Society for Transportation Studies. Conference
language : en
Publisher:
Release Date : 2006
Proceedings Of The Conference Of The Hong Kong Society For Transportation Studies written by Hong Kong Society for Transportation Studies. Conference and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Transportation categories.
Transportation Weekly Government Abstracts
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Author :
language : en
Publisher:
Release Date : 1982
Transportation Weekly Government Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1982 with Transportation categories.
Popular Mechanics
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Author :
language : en
Publisher:
Release Date : 2000-01
Popular Mechanics written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000-01 with categories.
Popular Mechanics inspires, instructs and influences readers to help them master the modern world. Whether it’s practical DIY home-improvement tips, gadgets and digital technology, information on the newest cars or the latest breakthroughs in science -- PM is the ultimate guide to our high-tech lifestyle.
Exploring The Potential Of Combining Ramp Metering And Variable Speed Limit Strategies For Alleviating Real Time Crash Risk On Urban Freeways
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Author : Kirolos Maged Haleem
language : en
Publisher:
Release Date : 2007
Exploring The Potential Of Combining Ramp Metering And Variable Speed Limit Strategies For Alleviating Real Time Crash Risk On Urban Freeways written by Kirolos Maged Haleem and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
In summary, Ramp Metering was more beneficial at congested situations, while Variable Speed Limits were more beneficial at free-flow conditions. At conditions approaching congestion, the combination of Ramp Metering and Variable Speed Limits produced the best benefits. These results illustrate the significant potential of ITS strategies to improve the safety and efficiency of urban freeways.
Proactive Integrated Control For Relieving Freeway Congestion
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Author : Xu Wang
language : en
Publisher:
Release Date : 2015
Proactive Integrated Control For Relieving Freeway Congestion written by Xu Wang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Ramp metering (Traffic engineering) categories.
Active bottlenecks limit traffic flow on freeway corridors. To relieve bottleneck severity, ramp metering (RM), variable speed limit (VSL) and their integration are often implemented to control the on-ramp and mainline input flow. Currently, freeway operation has become proactive based on short-term prediction. Macroscopic traffic flow models are often applied as prediction models in proactive traffic control strategies. Prior to field implementation, the models need to be calibrated and validated carefully to ensure that they represent real-life traffic situations. This study proposes modifications for METANET model to adapt it to the unpredictability of bottleneck activation during peak hours. The modified model is calibrated and verified its improvement of model prediction accuracy from segment-specific parameters. The modified model is validated that it can replicate traffic state evolutions during peak hours and be applicable in proactive traffic control practice. Weaving maneuvers (i.e., intensive lane changes) are a major cause of bottlenecks during high-demand periods. To consider weaving impacts in RM, this study introduces a proactive optimal RM algorithm that uses dynamic weaving capacity at weaving segments. Sensitivities of capacity and capacity drop are applied to dynamically estimate weaving capacity within a macroscopic traffic flow model. The proposed traffic flow model conducts estimation in a model predictive control (MPC) frame-work. The proposed RM algorithm is evaluated in macro-simulation and its effectiveness is enhanced by real-time estimated weaving capacity. The RM control research reveals a need of theoretical methods for weaving capacity estimation. This study then defines a linear optimization problem to solve weaving capacity and then establishes a lane-changing model to constrain the weaving flows. The proposed method is evaluated and analyzed for sensitivity with field data from two weaving segments. The capacity estimates from the proposed model are consistent with those from the HCM 2010 model and with field observations. Moreover, the weaving capacity is sensitive to weaving maneuvers. The proposed method is finally applied to estimate the real-time maximum discharge flow rate; the estimates match field measurements. Next, this study presents a proactive integrated control of RM and VSL, with goals to improve network-wide travel time and traffic flow. By decoupling the traffic prediction and simulation models, the possible control error sources are analyzed. The evaluation reveals the proactive integrated control achieves an amelioration in total time spent (TTS) up to 13.65% and an increase in total travel distance (TTD) up to 3.41%. The isolated and integrated controls benefit the traffic network in different extent under different demand scenarios. In addition, control rate profiles are analyzed in detail and found that RM is activated during slight congestion and the most congested situation to assist VSL. Through the integration, the infrastructure utility is maximized. Speed transition zones are complex when dynamically created and shifted by VSL. This study then attempts to represent speed limit effect and estimate real-time driver compliance at speed transition zones. The field data from two speed transition zones are investigated for temporal and spatial variations of speed and driver compliance using statistical tests. After selecting several key factors from statistical tests, a linear regression is established to rank the contributions of the selected factors and other general factors proposed by previous research. The regression results confirm speed limit value, surrounding traffic speed and existence of activated speed enforcement or education devices contribute more to driver compliance. Finally, this study reports the preliminary VSL test and details its implementation procedure on Whitemud Drive, Edmonton, Canada. DynaTAM-VSL software is designed to realize all necessary functions for VSL filed implementation. The preliminary test is conducted, and the VSL control performance and reliability are evaluated. The results for before-and-after VSL control are finally analyzed in depth. The analysis compares average traffic speed, standard deviation of speed, total travel time and total travel distance. The results from this study confirm that VSL can relieve recurrent traffic congestion.
Optimization And Microsimulation Of On Ramp Metering For Congested Freeways
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Author : Gabriel Clemente Gomes
language : en
Publisher:
Release Date : 2004
Optimization And Microsimulation Of On Ramp Metering For Congested Freeways written by Gabriel Clemente Gomes and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Express highway interchanges categories.
This dissertation investigates various aspect of the design and testing of on-ramp metering control systems, including optimization-based control and microscopic freeway modeling. A new technique for generating optimal metering plans is developed. As with most predictive designs, the ramp metering rates are found as the solution to a nonlinear optimization problem. In contrast to previous designs, the new approach 1) produces a globally optimal solution to the nonlinear problem, 2) requires only to solve a single linear program, and 3) allows the enforcement of hard constraints on the on-ramp queue lengths. The price that is paid for these features is that the objective function being minimized is not Total Travel Time, but rather a member of a class of "TTT-like" objective functions. A TTT-like objective function is defined as a linear combination of mainline flows with weights that, similarly to the Total Travel Time cost weights, decrease linearly in time from some initial value to zero at the final time. An example application of the technique shows that the globally optimal metering plan with respect to a TTT-like objective function also performs well in terms of Total Travel Time. A macroscopic analysis of local traffic-responsive ramp metering on a short stretch of freeway, with a single on-ramp and no offramps, is also presented. The study compares the performance of two popular local traffic-responsive ramp metering algorithms: Alinea and Percent-Occupancy, and addresses issues pertaining to parameter tuning and loop-detector placement. The second half of the dissertation describes the construction of a detailed microsimulation model of a stretch of Interstate 210 in Pasadena, CA. The VISSIM microsimulation package was used to create this model. Descriptions of the data gathering and processing procedures, bottleneck identification, network coding, and model calibration are provided. The model is used to test the performance of candidate local traffic-responsive controllers. Questions concerning the relative merits of these controllers, parameter tuning, and loop-detector placement are addressed in the context of the large-scale microscopic model.
Evaluation Of Variable Speed Limits Using A Genetic Algorithm Approach To Calibrate A Vissim Model
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Author : Brian Joseph Schaefer
language : en
Publisher:
Release Date : 2010
Evaluation Of Variable Speed Limits Using A Genetic Algorithm Approach To Calibrate A Vissim Model written by Brian Joseph Schaefer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Evolutionary programming (Computer science) categories.
"The variable speed limit (VSL) system has been adopted on more and more roadways across the globe as an engineering tool for controlling traffic flow, particularly during congestion situations. An important and fundamental question raised among traffic engineers is: Are the costs of installing and operating variable speed limits really justified? In order to answer this question, this thesis measures the effectiveness of the VSL system applying the VISSIM microscopic simulation model to a non-recurrent congestion situation. For the analysis, a section of interstate was modeled in VISSIM and calibrated so that the simulated results closely reproduce the observed data collected from traffic detectors. The calibration process is accomplished using a genetic algorithm (GA) programmed in MATLAB. Once the interstate system is calibrated to the static speed limit condition, the VSL system is portrayed on the model by temporarily blocking lanes to measure the effectiveness of VSL during an incident situation. Multiple incident locations and different VSL configurations are tested to investigate various possible forms of reality. The simulated results of with-VSL and without-VSL systems were compared and evaluated. The results show that no significant changes in travel times are observed, but queue lengths and fuel consumption decrease by 10-20% and 3-5% respectively. The speed variances upstream of the incidents also decreased 10-25% depending on location, which in the end may lead to fewer crashes. Before a VSL system is constructed a study should be conducted to determine if the cost of installing and maintaining the system is justified by the benefits. The benefits of a VSL system include a decrease in fuel consumption as well as a decrease in the deviation of speeds, potentially leading to a reduction in crashes. Further studies need to be done to determine exactly how much the number of crashes could potentially be reduced. If a governing authority has the means for a VSL system they could potentially be justified by a reduction in crashes on the roadway, but the breadth of this thesis does not have enough evidence to support the case that there will be a definite reduction in the number of crashes"--Abstract, leaf iii.
Speed Harmonization And Peak Period Shoulder Use To Manage Urban Freeway Congestion
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Author :
language : en
Publisher:
Release Date : 2009
Speed Harmonization And Peak Period Shoulder Use To Manage Urban Freeway Congestion written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Roads categories.