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Author : Paul Brian Wolshon
Publisher :
ISBN 13 :
Total Pages : 17 pages
Book Rating : 4.:/5 (39 download)
Download or read book Analysis of Intersection Delay Under Real-time Adaptive Signal Control written by Paul Brian Wolshon and published by . This book was released on 1998 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Paul Brian Wolshon
Publisher :
ISBN 13 :
Total Pages : 292 pages
Book Rating : 4.3/5 (129 download)
Download or read book Development of a Modeling Approach to Analyze Intersection Traffic Delay Under the Control of a Real-time Adaptive Traffic Signal System written by Paul Brian Wolshon and published by . This book was released on 1997 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Ahmed Shawky Abdel-Rahim
Publisher :
ISBN 13 :
Total Pages : 366 pages
Book Rating : 4.3/5 (129 download)
Download or read book Analysis of Adaptive Signal Control Strategies in Urban Corridors written by Ahmed Shawky Abdel-Rahim and published by . This book was released on 1998 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jialei Mao
Publisher :
ISBN 13 :
Total Pages : 75 pages
Book Rating : 4.:/5 (428 download)
Download or read book Automatic System to Measure Turning Movement and Intersection Delay written by Jialei Mao and published by . This book was released on 2009 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: "It is important for many traffic operations, such as real-time adaptive signal control, dynamic traffic assignment and traffic demand estimation, to obtain the vehicle turning movement information at a signalized intersection. However, it is laborious and time consuming to count the turning movements manually. Previous efforts on this problem relied on a mathematical approach by solving an O-D matrix in which the turning movements represent distributions of the arriving flow at each intersection approach. However, such a matrix cannot be mathematically solved without using supplementary volume data from the local detectors; previous studies showed the results from the O-D method are not accurate. Identifying vehicle turning movements from detector information is a more direct method. Limited studies using this method have been found for intersections without shared lanes. Most intersections allow shared lane operations, thus this method is not practical without further improvements. Driven by the need to identify vehicles turning movement automatically regardless of the geometry and operation of the intersections, this research studied and developed a system called Automatic Turning Movement Identification System (ATMIS). ATMIS utilizes intelligent detection matching algorithm to identify vehicle turning movements from the detections collected from the field in real-time. This algorithm has the capability to compensate the error caused by the faults detections and shared lanes. The results from laboratory experiments and field tests are very encouraging. Future work is also discussed in the thesis. While another related study, intersection delay measurement, is also included in this thesis. Delay is regarded as one of the most important Measures of Effectiveness (MOE) for signalized intersections. Different methods to measure control delay are recommended by many researchers but most of them are costly, time consuming and labor intensive. Some key components of delay measurement, such as intersection delay and delay for different turning movements, are not addressed in the previous studies. Driven by the need to develop an automatic delay estimation system, a method is presented to improve or extend the current methods to estimate intersection travel time based on the detection information derived from ATMIS. Yet, the detection information is not perfect from ATMIS, we still can estimate intersection delay accurately with the help of data filters. The mechanism and result of proposed method are discussed in this thesis. Further work of delay measurement is also presented."--Abstract.
Author : U.s. Department of Transportation
Publisher : CreateSpace
ISBN 13 : 9781508557173
Total Pages : 286 pages
Book Rating : 4.5/5 (571 download)
Download or read book Traffic Signal Timing Manual written by U.s. Department of Transportation and published by CreateSpace. This book was released on 2015-02-20 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report serves as a comprehensive guide to traffic signal timing and documents the tasks completed in association with its development. The focus of this document is on traffic signal control principles, practices, and procedures. It describes the relationship between traffic signal timing and transportation policy and addresses maintenance and operations of traffic signals. It represents a synthesis of traffic signal timing concepts and their application and focuses on the use of detection, related timing parameters, and resulting effects to users at the intersection. It discusses advanced topics briefly to raise awareness related to their use and application. The purpose of the Signal Timing Manual is to provide direction and guidance to managers, supervisors, and practitioners based on sound practice to proactively and comprehensively improve signal timing. The outcome of properly training staff and proactively operating and maintaining traffic signals is signal timing that reduces congestion and fuel consumption ultimately improving our quality of life and the air we breathe. This manual provides an easy-to-use concise, practical and modular guide on signal timing. The elements of signal timing from policy and funding considerations to timing plan development, assessment, and maintenance are covered in the manual. The manual is the culmination of research into practices across North America and serves as a reference for a range of practitioners, from those involved in the day to day management, operation and maintenance of traffic signals to those that plan, design, operate and maintain these systems.
Author : Tianxin Li (M.S. in Engineering)
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (141 download)
Download or read book Adaptive Traffic Signal Control Using Deep Reinforcement Learning for Network Traffic Incidents written by Tianxin Li (M.S. in Engineering) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Traffic signal control is an essential aspect of urban mobility that significantly impacts the efficiency and safety of transportation networks. Traditional traffic signal control systems rely on fixed-time or actuated signal timings, which may not adapt to the dynamic traffic demands and congestion patterns. Therefore, researchers and practitioners have increasingly turned to reinforcement learning (RL) techniques as a promising approach to improve the performance of traffic signal control. This dissertation investigates the application of RL algorithms to traffic signal control, aiming to optimize traffic flow and reduce congestion. The study develops a simulation model of a signalized intersection and trains RL agents to learn how to adjust signal timings based on real-time traffic conditions. The RL agents are designed to learn from experience and adapt to changing traffic patterns, thereby improving the efficiency of traffic flow, even for scenarios in which traffic incidents occur in the network. In this dissertation, the potential benefits of using RL algorithms to optimize traffic signal control in scenarios with and without traffic incidents were explored. To achieve this, an incident generation module was developed using the open-source traffic signal performance simulation framework that relies on the SUMO software. This module includes emergency response vehicles to mimic the realistic impact of traffic incidents and generates incidents randomly in the network. By exposing the RL agent to this environment, it can learn from the experience and optimize traffic signal control to reduce system delay. The study began with a single intersection scenario, where the DQN algorithm was modeled to form the RL agent traffic signal controller. To improve the training process and model performance, experience replay and target network were implemented to solve the limitations of DQN. Hyperparameter tuning was conducted to find the best parameter combination for the training process, and the results showed that DQN outperformed other controllers in terms of the system-wise and intersection-wise queue distribution and vehicle delay. The study was then extended to a small corridor with 2 intersections and a grid network (2x2 intersection), and the incident generation module was used to expose the RL agent to different traffic scenarios. Again, hyperparameter tuning was conducted, and the DQN model outperformed other controllers in terms of reducing congestion and improving the system performance. The robustness of the DQN performance was also tested with different demands, and the microsimulation results showed that the DQN performance was consistent. Overall, this study highlights the potential of RL algorithms to optimize traffic signal control in scenarios with and without traffic incidents. The incident generation module developed in this study provides a realistic environment for the RL agent to learn and adapt, leading to improved system performance and reduced congestion. In addition, hyperparameter tuning is essential to lay down a solid foundation for the RL training process
Author : Peter T. Martin
Publisher :
ISBN 13 :
Total Pages : 44 pages
Book Rating : 4.3/5 (555 download)
Download or read book Adaptive Signal Control V written by Peter T. Martin and published by . This book was released on 2008 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2005, the Utah Department of Transportation (UDOT) installed the Sydney Coordinated Adaptive Traffic System (SCATS) in Park City, Utah, on its network of 14 signalized intersections. A field evaluation compared previous time-of-day actuated-coordinated signal timings with those dynamically computed by SCATS. Travel times, travel time stopped delay and number of stops were collected by driving probe vehicles on the major routes. Intersection stopped delays were also collected to investigate traffic performance on side streets. Overall, SCATS consistently reduced travel times and travel time stopped delay, the average number of stops, and intersection stopped delay for major and minor through movements.
Author : Ibrahem Mahmoud Shatnawi
Publisher :
ISBN 13 :
Total Pages : 200 pages
Book Rating : 4.:/5 (987 download)
Download or read book Automated Vehicle Delay and Travel Time Estimation Techniques for Improved Performance Measures of Urban Network System written by Ibrahem Mahmoud Shatnawi and published by . This book was released on 2015 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vehicle delay and travel time are considered the most important measures of effectiveness (MOE) in urban arterial roads. They allow traffic engineers to evaluate the performance of a traffic system component or the effectiveness of the system wide control strategy. They are often utilized for real-time applications such as adaptive signal control, congestion management, and dynamic traffic assignment. However, obtaining intersection performance data in real-time, including average control delay and travel time, can be very time consuming and labor intensive. Three real-time logics: AVDET, AVTTET, and ANDET are proposed for estimating performance measures of isolated intersections, traffic corridors, and traffic networks. These approaches use the existing traffic detection system to estimate vehicle delay and travel time. By using a real-time traffic detection system as input, the algorithms used in real-time logics make use of information from both the detectors and the signal system of the intersection. By tracking each detector's status and traffic signal operation second by second, travel time, approach, and intersection delays can be estimated automatically. Results from the proposed algorithms are compared with those from simulation output, and statistical tests are conducted under varying traffic operation conditions. Also, the results are analyzed using different statistical techniques. The findings show that the proposed algorithms are able to yield reliable results in different traffic and signal control conditions and that the output is very stable. Future works are suggested to further examine and improve the performance of the proposed algorithms.
Author : C. Cai
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (829 download)
Download or read book Adaptive Traffic Signal Control Using Approximate Dynamic Programming written by C. Cai and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a study on an adaptive traffic signal controller for real-time operation. An approximate dynamic programming (ADP) algorithm is developed for controlling traffic signals at isolated intersection and in distributed traffic networks. This approach is derived from the premise that classic dynamic programming is computationally difficult to solve, and approximation is the second-best option for establishing sequential decision-making for complex process. The proposed ADP algorithm substantially reduces computational burden by using a linear approximation function to replace the exact value function of dynamic programming solution. Machine-learning techniques are used to improve the approximation progressively. Not knowing the ideal response for the approximation to learn from, we use the paradigm of unsupervised learning, and reinforcement learning in particular. Temporal-difference learning and perturbation learning are investigated as appropriate candidates in the family of unsupervised learning. We find in computer simulation that the proposed method achieves substantial reduction in vehicle delays in comparison with optimised fixed-time plans, and is competitive against other adaptive methods in computational efficiency and effectiveness in managing varying traffic. Our results show that substantial benefits can be gained by increasing the frequency at which the signal plans are revised. The proposed ADP algorithm is in compliance with a range of discrete systems of resolution from 0.5 to 5 seconds per temporal step. This study demonstrates the readiness of the proposed approach for real-time operations at isolated intersections and the potentials for distributed network control.
Author : Angela M. Coates
Publisher :
ISBN 13 :
Total Pages : 62 pages
Book Rating : 4.:/5 (94 download)
Download or read book Using Adaptive Signal Control to Prioritize Pedestrian Crossing at Continuous Flow Intersections written by Angela M. Coates and published by . This book was released on 2013 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: Traditional four-phase, four-legged intersections often operate inefficiently, severely restricting the available throughput and resulting in large delays. These configurations are limited by their traditional geometric design, and altering the geometry of the entire intersection can significantly increase capacity. Continuous flow intersections utilize an unconventional lane arrangement to maximize the vehicular throughput. This arrangement involves displacing left-turn lanes across opposing through traffic before the main intersection is reached. Such an alteration allows left and through vehicles to proceed simultaneously, and consequently, both the intersection capacity and delay are improved. Numerous studies have validated the operational improvements associated with continuous flow intersections, but pedestrian accommodation is oftentimes low due to the unconventional configuration. Both pedestrian delay and crossing distance are longer than desired, and the unfamiliar geometry makes navigating the intersection difficult and possibly unsafe. In this study, an enhanced continuous flow intersection configuration was proposed and tested to improve the pedestrian experience. Increased intersection delay is often a result of pedestrian crossing activities, for which an adaptive signal control program has been developed specifically for this intersection to reduce vehicle delay while prioritizing pedestrian crossing. The signal control procedure dynamically chooses the appropriate phase and green time combination to minimize delay by considering pedestrian wait time and existing queue size. Several simulation analyses were performed using this adaptive control methodology, and the results of this study have shown how its implementation can improve pedestrian accommodations while simultaneously minimizing vehicle delay at a continuous flow intersection.
Author : Michael Fontaine
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (918 download)
Download or read book Evaluation of the Virginia Department of Transportation Adaptive Signal Control Technology Pilot Project written by Michael Fontaine and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Currently, most traffic signals operated by the Virginia Department of Transportation (VDOT) use actuated plans that vary by time of day (TOD) and day of the week. These timing plans are typically developed off-line using traffic count information collected in the field and then processed using signal optimization software. This method works well as long as traffic volumes remain consistent with the conditions used to develop the timing plan, but timing plans can become suboptimal if traffic demands deviate from those conditions. Traffic growth over time, seasonal changes in traffic, special events, or incidents can all cause TOD plans to perform poorly, resulting in increased delays to drivers. As a result, VDOT must regularly retime signalized intersections to deal with long-term changes in travel patterns, which incurs costs to VDOT. Even so, non-recurring events can still cause TOD plans to perform poorly. Adaptive signal control technology (ASCT) is one tool that has been proposed to handle variable traffic demand better. VDOTs Traffic Engineering Division began a pilot program to install the InSync ASCT developed by Rhythm Engineering on 13 corridors around the state beginning in 2011. The InSync system uses enhanced detection along a corridor to adjust signal timing parameters dynamically to meet observed demand in real time, eliminating the need to develop static timing plans. This allows the ASCT system to adjust signal timing parameters to account for variations in flow attributable to special events, seasonal flows, incidents, or simply the increase of volumes over time. In this case, signal timings are not pre-defined based on historic data, so ASCT systems can potentially reduce delays created by outdated static TOD plans. These pilot deployments were evaluated to determine if ASCT created operational and safety improvements large enough to justify the additional costs to install ASCT. Data on mainline traffic operations, side street delays, and intersection crashes were collected with and without ASCT active. The results showed that mainline traffic operations generally improved if (1) the corridor was not oversaturated; (2) the corridor did not have characteristics that encourage platoon dispersion; and (3) the corridor did not already function well. Side street delays generally increased, although net benefits in overall corridor travel time were usually still observed. An empirical Bayes safety analysis of crashes at the intersections where ASCT was installed also found a 17% decrease in total crashes. Overall, ASCT generally produced a favorable benefit/cost ratio. The findings from the pilot tests were used to identify key considerations for future ASCT deployments so that VDOT could better identify future sites that might benefit from ASCT installation.
Author : Abhay Dnyaneshwar Lidbe
Publisher :
ISBN 13 :
Total Pages : 157 pages
Book Rating : 4.:/5 (974 download)
Download or read book Multi-perspective System-wide Analyses of Adaptive Traffic Signal Control Systems Using Microsimulation and Contemporary Data Sources written by Abhay Dnyaneshwar Lidbe and published by . This book was released on 2016 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary function of traffic signals is to assign the right of way to vehicular and pedestrian traffic at intersections. Effective traffic signal system reduces congestion, increases intersection capacity, and improves other traffic related performance measures such as safety and mobility. To ensure these goals are met, traffic signals require updated timings to maintain proper operation. These updated signal timings impact not only traffic performance, but overall transportation system efficiency. Because traditional signal timing plans may not accommodate variable and unpredictable traffic demands, a more proactive approach is necessary to ensure properly timed and maintained traffic signals. Adaptive traffic control systems (ATCS) continually collect data and optimize signal timing on a real time basis thereby reducing the aforementioned drawbacks of traditional signal retiming. Understanding and characterizing how these systems are working is important to transportation engineers, and evaluating these systems can provide useful insights. The objective of this dissertation is to develop evaluation methodologies (both operational and economical) for adaptive traffic signal control that go beyond the traditional assessments that use traffic measures of effectiveness (MOEs). Case studies are conducted for Sydney Coordinated Adaptive Traffic System (SCATS) implementations in Alabama, which are useful in objective evaluations of ATCS (in general) for both their current and future operational environments by using microsimulation techniques and/or field data from contemporary data sources. The study contains detailed comparative analyses of traffic operations of the study corridors for existing peak hour traffic conditions under the previous time-of-day (TOD) plan and similar peak hour conditions after SCATS implementation. Although simulation analysis using VISSIM traffic microsimulation software is the primary methodological technique used for evaluating comparative performances, arterial data from other sources (Bluetooth MAC Address Matching and crowdsourced travel data) are also used to perform the evaluations, which is a novel application for this context. While past studies have considered either the arterial or its side-streets performances in their evaluations, this work explored a system-wide approach looking at the composite performance of both dimensions together. Finally, for transportation agencies which operate within budget constraints, it is important to know the real worth of attaining the benefits from ATCS implementations. The last chapter of this dissertation extends the evaluation methodology to include benefit-cost analysis (BCA) by evaluating the ATCS performance for both current and future traffic conditions. This information will be helpful for transportation agencies, planners, and practitioners to understand and justify their ATCS investment and also serve as a guideline for their future ITS projects.
Author : Michael D. Fontaine
Publisher :
ISBN 13 :
Total Pages : 51 pages
Book Rating : 4.:/5 (913 download)
Download or read book Evaluation of the Virginia Department of Transportation Adaptive Signal Control Technology Pilot Project written by Michael D. Fontaine and published by . This book was released on 2015 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: Currently, most traffic signals operated by the Virginia Department of Transportation (VDOT) use actuated plans that vary by time of day (TOD) and day of the week. These timing plans are typically developed off-line using traffic count information collected in the field and then processed using signal optimization software. This method works well as long as traffic volumes remain consistent with the conditions used to develop the timing plan, but timing plans can become suboptimal if traffic demands deviate from those conditions. Traffic growth over time, seasonal changes in traffic, special events, or incidents can all cause TOD plans to perform poorly, resulting in increased delays to drivers. As a result, VDOT must regularly retime signalized intersections to deal with long-term changes in travel patterns, which incurs costs to VDOT. Even so, non-recurring events can still cause TOD plans to perform poorly. Adaptive signal control technology (ASCT) is one tool that has been proposed to handle variable traffic demand better. VDOTs Traffic Engineering Division began a pilot program to install the InSync ASCT developed by Rhythm Engineering on 13 corridors around the state beginning in 2011. The InSync system uses enhanced detection along a corridor to adjust signal timing parameters dynamically to meet observed demand in real time, eliminating the need to develop static timing plans. This allows the ASCT system to adjust signal timing parameters to account for variations in flow attributable to special events, seasonal flows, incidents, or simply the increase of volumes over time. In this case, signal timings are not pre-defined based on historic data, so ASCT systems can potentially reduce delays created by outdated static TOD plans. These pilot deployments were evaluated to determine if ASCT created operational and safety improvements large enough to justify the additional costs to install ASCT. Data on mainline traffic operations, side street delays, and intersection crashes were collected with and without ASCT active. The results showed that mainline traffic operations generally improved if (1) the corridor was not oversaturated; (2) the corridor did not have characteristics that encourage platoon dispersion; and (3) the corridor did not already function well. Side street delays generally increased, although net benefits in overall corridor travel time were usually still observed. An empirical Bayes safety analysis of crashes at the intersections where ASCT was installed also found a 17% decrease in total crashes. Overall, ASCT generally produced a favorable benefit/cost ratio. The findings from the pilot tests were used to identify key considerations for future ASCT deployments so that VDOT could better identify future sites that might benefit from ASCT installation.
Author : Dunhao Zhong
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (129 download)
Download or read book Reinforcement Learning-Based Traffic Signal Control for Signalized Intersections written by Dunhao Zhong and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Vehicles have become an indispensable means of transportation to ensure people's travel and living materials. However, with the increasing number of vehicles, traffic congestion has become severe and caused a lot of social wealth loss. Therefore, improving the efficiency of transport management is one of the focuses of current academic circles. Among the research in transport management, traffic signal control (TSC) is an effective way to alleviate traffic congestion at signalized intersections. Existing works have successfully applied reinforcement learning (RL) techniques to achieve a higher TSC efficiency. However, previous work remains several challenges in RL-based TSC methods. First, existing studies used a single scaled reward to frame multiple objectives. Nevertheless, the single scaled reward has lower scalability to assess the controller's performance on different objectives, resulting in higher volatility on different traffic criteria. Second, adaptive traffic signal control provides dynamic traffic timing plans according to unforeseeable traffic conditions. Such characteristic prohibits applying the existing eco-driving strategies whose strategies are generated based on foreseeable and prefixed traffic timing plans. To address the challenges, in this thesis, we propose to design a new RL-TSC framework along with an eco-driving strategy to improve the TSC's efficiency on multiple objectives and further smooth the traffic flows. Moreover, to achieve effective management of the system-wide traffic flows, current researches tend to focus on the design of collaborative traffic signal control methods. However, the existing collaboration-based methods often ignore the impact of transmission delay for exchanging traffic flow information on the system. Inspired by the state-of-the-art max-pressure control in the traffic signal control area, we propose a new efficient RL-based cooperative TSC scheme by improving the reward and state representation based on the max-pressure control method and developing an agent that can address the data transmission delay issue by decreasing the discrepancy between the real-time and delayed traffic conditions. To evaluate the performance of our proposed work more accurately, in addition to the synthetic scenario, we also conducted an experiment based on the real-world traffic data recorded in the City of Toronto. We demonstrate that our method surpassed the performance of the previous traffic signal control methods through comprehensive experiments.
Author : Stefan Voß
Publisher : Springer Science & Business Media
ISBN 13 : 3642564232
Total Pages : 465 pages
Book Rating : 4.6/5 (425 download)
Download or read book Computer-Aided Scheduling of Public Transport written by Stefan Voß and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume consists of selected papers presented at the Eighth International Conference on Computer-Aided Scheduling 0/Public Transport (CASPT 2000), which was held at the conference center of the Konrad rd Adenauer-Foundation in Berlin, Germany, from June 2pt to 23 , 2000. The CASPT 2000 is the continuation of aseries of international workshops and conferences presenting recent research and progress in computer-aided scheduling in public transport.Previous workshops and conferences were held in • Chicago (1975), • Leeds (1980), • Montreal (1983 and 1990), • Hamburg (1987), • Lisbon (1993) and • Cambridge, Mass. (1997).1 With CASPT 2000, our series of workshops and conferences celebrated th its 25 anniversary. Starting with a Workshop on Automated Techniques [or Scheduling 0/ Vehicle Operators [or Urban Public Transportation Services in 1975 the scope and purpose has broadened since and still continues to do so. The previous workshops and conferences were focused on public mass transit, and while this remained the primary focus ofthe 2000 conference, it included also computer-aided scheduling methods being developed and applied in re lated means of passenger transport systems. Commonalities regarding op erations research techniques such as, e.g., column generation techniques and 1 While there were no formal proceedings for the first workshop but only a p- printed copy of all papers issued to participants on arrival, the subsequent ones are weil documented as folIows: Wren, A. (Ed.) (1981). Computer Scheduling 0/ Public Transport. North Holland, Amsterdam.
Author : Ehsan Bagheri
Publisher :
ISBN 13 :
Total Pages : 168 pages
Book Rating : 4.:/5 (13 download)
Download or read book Enhanced Traffic Signal Operation Using Connected Vehicle Data written by Ehsan Bagheri and published by . This book was released on 2017 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: As traffic on urban road network increases, congestion and delays are becoming more severe. At grade intersections form capacity bottlenecks in urban road networks because at these locations, capacity must be shared by competing traffic movements. Traffic signals are the most common method by which the right of way is dynamically allocated to conflicting movements. A range of traffic signal control strategies exist including fixed time control, actuated control, and adaptive traffic signal control (ATSC). ATSC relies on traffic sensors to estimate inputs such as traffic demands, queue lengths, etc. and then dynamically adjusts signal timings with the objective to minimize delays and stops at the intersection. Despite, the advantages of these ATSC systems, one of the barriers limiting greater use of these systems is the large number of traffic sensors required to provide the essential information for their signal timing optimization methodologies. A recently introduced technology called connected vehicles will make vehicles capable of providing detailed information such as their position, speed, acceleration rate, etc. in real-time using a wireless technology. The deployment of connected vehicle technology would provide the opportunity to introduce new traffic control strategies or to enhance the existing one. Some work has been done to-date to develop new ATSC systems on the basis of the data provided by connected vehicles which are mainly designed on the assumption that all vehicles on the network are equipped with the connected vehicle technology. The goals of such systems are to: 1) provide better performance at signalized intersections using enhanced algorithms based on richer data provided by the connected vehicles; and 2) reduce (or eliminate) the need for fixed point detectors/sensors in order to reduce deployment and maintenance costs. However, no work has been done to investigate how connected vehicle data can improve the performance of ATSC systems that are currently deployed and that operate using data from traditional detectors. Moreover, achieving a 100% market penetration of connected vehicles may take more than 30 years (even if the technology is mandated on new vehicles). Therefore, it is necessary to provide a solution that is capable of improving the performance of signalized intersections during this transition period using connected vehicle data even at low market penetration rates. This research examines the use of connected vehicle data as the only data source at different market penetration rates aiming to provide the required inputs for conventional adaptive signal control systems. The thesis proposes various methodologies to: 1) estimate queues at signalized intersections; 2) dynamically estimate the saturation flow rate required for optimizing the timings of traffic signals at intersections; and 3) estimate the free flow speed on arterials for the purpose of optimizing offsets between traffic signals. This thesis has resulted in the following findings: 1. Connected vehicle data can be used to estimate the queue length at signalized intersections especially for the purpose of estimating the saturation flow rate. The vehicles' length information provided by connected vehicles can be used to enhance the queue estimation when the traffic composition changes on a network. 2. The proposed methodology for estimating the saturation flow rate is able to estimate temporally varying saturation flow rates in response to changing network conditions, including lane blockages and queue spillback that limit discharge rates, and do so with an acceptable range of errors even at low level of market penetration of connected vehicles. The evaluation of the method for a range of traffic Level of Service (LOS) shows that the maximum observed mean absolute relative error (6.2%) occurs at LOS F and when only 10% of vehicles in the traffic stream are connected vehicles. 3. The proposed method for estimating the Free Flow Speed (FFS) on arterial roads can provide estimations close to the known ground truth and can respond to changes in the FFS. The results also show that the maximum absolute error of approximately 4.7 km/h in the estimated FFS was observed at 10% market penetration rate of connected vehicles. 4. The results of an evaluation of an adaptive signal control system based on connected vehicle data in a microsimulation environment show that the adaptive signal control system is able to adjust timings of signals at intersections in response to changes in the saturation flow rate and free flow speed estimated from connected vehicle data using the proposed methodologies. The comparison of the adaptive signal control system against a fixed time control at 20% and 100% CV market penetration rates shows improvements in average vehicular delay and average number of stops at both market penetration rates and though improvements are larger for 100% CV LMP, approximately 70% of these improvements are achieved at 20% CV LMP.
Author :
Publisher :
ISBN 13 :
Total Pages : 256 pages
Book Rating : 4.3/5 (555 download)
Download or read book Evaluation of Adaptive Control Strategies for NJ Highways written by and published by . This book was released on 2006 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
