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Off Line Calibration Of Dynamic Traffic Assignment
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Book Synopsis Off-line Calibration of Dynamic Traffic Assignment by : Ramachandran Balakrishna
Download or read book Off-line Calibration of Dynamic Traffic Assignment written by Ramachandran Balakrishna and published by VDM Publishing. This book was released on 2007 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic Traffic Assignment (DTA) models estimate and predict the evolution of congestion through detailed models and algorithms that capture travel demand, network supply and their complex interactions. The availability of rich time-varying traffic data spanning multiple days, collected by automatic surveillance technology, provides the opportunity to calibrate such a DTA model's many inputs and parameters so that its outputs reflect field conditions. DTA models are generally calibrated sequentially: supply model calibration (assuming known demand inputs) is followed by demand calibration with fixed supply parameters. This book develops an off-line DTA model calibration methodology for the simultaneous estimation of all demand and supply inputs and parameters, using sensor data. A complex, non-linear, stochastic optimization problem is solved, using any general traffic data. Case studies with DynaMIT, a DTA model with traffic estimation and prediction capabilities, indicate that the simultaneous approach significantly outperforms the sequential state of the art. This book is addressed to professionals and researchers who apply large-scale transportation models.
Book Synopsis Off-line Calibration of Dynamic Traffic Assignment Models by : Ramachandran Balakrishna
Download or read book Off-line Calibration of Dynamic Traffic Assignment Models written by Ramachandran Balakrishna and published by . This book was released on 2006 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) Case studies with DynaMIT, a DTA model with traffic estimation and prediction capabilities, are used to demonstrate and validate the proposed methodology. A synthetic traffic network with known demand parameters and simulated sensor data is used to illustrate the improvement over the sequential approach, the ability to accurately recover underlying model parameters, and robustness in a variety of demand and supply situations. Archived sensor data and a network from Los Angeles, CA are then used to demonstrate scalability. The benefit of the proposed methodology is validated through a real-time test of the calibrated DynaMIT's estimation and prediction accuracy, based on sensor data not used for calibration. Results indicate that the simultaneous approach significantly outperforms the sequential state of the art.
Book Synopsis On-line Calibration for Dynamic Traffic Assignment Models by : Constantinos Antoniou
Download or read book On-line Calibration for Dynamic Traffic Assignment Models written by Constantinos Antoniou and published by VDM Publishing. This book was released on 2007 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Traffic estimation and prediction (or dynamic traffic assignment) models are expected to contribute to the reduction of travel time delays. In this book, an on-line calibration approach that jointly estimates all model parameters is presented. The methodology imposes no restrictions on the models, the parameters or the data that can be handled, and emerging or future data can be easily incorporated. The modeling approach is applicable to any simulation model and is not restricted to the application domain covered in this book. Several modified, non-linear Kalman Filter methodologies are presented, e.g. Extended Kalman Filter (EKF), Iterated EKF, Limiting EKF, and Unscented Kalman Filter. Extensive case studies on freeway networks in Europe and the US are used to demonstrate the approach, to verify the importance of on-line calibration, and to test the presented algorithms. The main target audience of this book comprises Intelligent Transportation Systems researchers and graduate students, as well as practitioners, including Metropolitan Planning Organization engineers and Traffic Management Center operators, and any reader with an interest in dynamic state and parameter estimation.
Download or read book W-SPSA written by Lu Lu (S.M.) and published by . This book was released on 2014 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: The off-line calibration is a crucial step for the successful application of Dynamic Traffic Assignment (DTA) models in transportation planning and real time traffic management. While traditional approaches focus on the separate or sequential estimation of demand and supply in a DTA system, a recently proposed framework calibrates the demand and supply models simultaneously by formulating the off-line calibration as a constrained optimization problem. Simultaneous Perturbation Stochastic Approximation (SPSA) has been reported in the literature to be the most suitable solution algorithm for this problem due to its highly efficient gradient estimation approach. However, it turns out that the performance of SPSA in terms of convergence rate and long run accuracy can deteriorate significantly when the physical network size and the number of considered time intervals increase. To overcome this problem, this thesis proposes a new algorithm, called Weighted SPSA, or W-SPSA. W-SPSA improves SPSA's gradient estimation process by effectively reducing the noise generated by irrelevant measurements. Synthetic tests are performed to systematically compare the performance of SPSA and W-SPSA. W-SPSA shows scalability and robustness in the tests and outperforms SPSA under different problem scales and characteristics. The application of W-SPSA in real world large-scale DTA systems is demonstrated with a case study of the entire Singapore expressway network. Results show that WSPSA is a more suitable algorithm than SPSA for the off-line calibration of large-scale DTA models. The contributions of the thesis include: 1) identifying limitations of a state-of-the- art solution algorithm for the DTA off-line calibration problem, 2) presenting rigorous definitions of an enhanced algorithm and proposing approaches to estimate the required algorithm parameters, 3) systematically comparing the performance of the new algorithm against the state-of-the-art, 4) demonstrating the characteristics of the new algorithm through experiments, and 5) discussing the general steps and empirical technical considerations when tackling real world DTA off-line calibration problems.
Book Synopsis On-line calibration for dynamic traffic assignment by : Constantinos Antoniou
Download or read book On-line calibration for dynamic traffic assignment written by Constantinos Antoniou and published by . This book was released on 2004 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) application, the EKF has more desirable properties than the UKF. Furthermore, the Limiting EKF provides accuracy comparable to that of the best algorithm (EKF), but with computational complexity which is order(s) of magnitude lower than the other algorithms.
Book Synopsis Algorithmic and Implementation Aspects of On-line Calibration of Dynamic Traffic Assignment by : Enyang Huang
Download or read book Algorithmic and Implementation Aspects of On-line Calibration of Dynamic Traffic Assignment written by Enyang Huang and published by . This book was released on 2010 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis compares alternative and proposes new candidate algorithms for the online calibration of Dynamic Traffic Assignment (DTA). The thesis presents two formulations to on-line calibration: 1) The classical statespace formulation and 2) The direct optimization formulation. Extended Kalman Filter (EKF) is presented and validated under the state-space formulation. Pattern Search (PS), Conjugate Gradient Method (CG) and Gradient Descent (GD) are presented and validated under the direct optimization formulation. The feasibility of the approach is demonstrated by showing superior accuracy performance over alternative DTA model with limited calibration capabilities. Although numerically promising, the computational complexity of these base-line algorithms remain high and their application to large networks is still questionable. To address the issue of scalability, this thesis proposes novel extensions of the aforementioned GD and EKF algorithms. On the side of algorithmic advancement, the Partitioned Simultaneous Perturbation (PSP) method is proposed to overcome the computational burden associated with the Jacobian approximation within GD and EKF algorithms. PSP-GD and PSP-EKF prove to be capable of producing prediction results that are comparable to that of the GD and EKF, despite achieving speed performance that are orders of magnitude faster. On the side of algorithmic implementation, the computational burden of EKF and GD are distributed onto multiple processors. The feasibility and effectiveness of the Para-GD and Para-EKF algorithms are demonstrated and it is concluded that that distributed computing significantly increases the overall calibration speed.
Book Synopsis Observability of Origin-Destination Matrices for Dynamic Traffic Assignment by : Ashish Gupta (S.M.)
Download or read book Observability of Origin-Destination Matrices for Dynamic Traffic Assignment written by Ashish Gupta (S.M.) and published by . This book was released on 2005 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: (cont.) A comprehensive off-line calibration exercise for the same network is then used to verify the validity of the conclusion.
Book Synopsis Fundamentals of Traffic Simulation by : Jaume Barceló
Download or read book Fundamentals of Traffic Simulation written by Jaume Barceló and published by Springer Science & Business Media. This book was released on 2011-01-06 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing power of computer technologies, the evolution of software en- neering and the advent of the intelligent transport systems has prompted traf c simulation to become one of the most used approaches for traf c analysis in s- port of the design and evaluation of traf c systems. The ability of traf c simulation to emulate the time variability of traf c phenomena makes it a unique tool for capturing the complexity of traf c systems. In recent years, traf c simulation – and namely microscopic traf c simulation – has moved from the academic to the professional world. A wide variety of traf- c simulation software is currently available on the market and it is utilized by thousands of users, consultants, researchers and public agencies. Microscopic traf c simulation based on the emulation of traf c ows from the dynamics of individual vehicles is becoming one the most attractive approaches. However, traf c simulation still lacks a uni ed treatment. Dozens of papers on theory and applications are published in scienti c journals every year. A search of simulation-related papers and workshops through the proceedings of the last annual TRB meetings would support this assertion, as would a review of the minutes from speci cally dedicated meetings such as the International Symposiums on Traf c Simulation (Yokohama, 2002; Lausanne, 2006; Brisbane, 2008) or the International Workshops on Traf c Modeling and Simulation (Tucson, 2001; Barcelona, 2003; Sedona, 2005; Graz 2008). Yet, the only comprehensive treatment of the subject to be found so far is in the user’s manuals of various software products.
Book Synopsis A Dual Approximation Framework for Dynamic Network Analysis by : Dung-Ying Lin
Download or read book A Dual Approximation Framework for Dynamic Network Analysis written by Dung-Ying Lin and published by . This book was released on 2009 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic Traffic Assignment (DTA) is gaining wider acceptance among agencies and practitioners because it serves as a more realistic representation of real-world traffic phenomena than static traffic assignment. Many metropolitan planning organizations and transportation departments are beginning to utilize DTA to predict traffic flows within their networks when conducting traffic analysis or evaluating management measures. To analyze DTA-based optimization applications, it is critical to obtain the dual (or gradient) information as dual information can typically be employed as a search direction in algorithmic design. However, very limited number of approaches can be used to estimate network-wide dual information while maintaining the potential to scale. This dissertation investigates the theoretical/practical aspects of DTA-based dual approximation techniques and explores DTA applications in the context of various transportation models, such as transportation network design, off-line DTA capacity calibration and dynamic congestion pricing. Each of the later entities is formulated as bi-level programs. Transportation Network Design Problem (NDP) aims to determine the optimal network expansion policy under a given budget constraint. NDP is bi-level by nature and can be considered a static case of a Stackelberg game, in which transportation planners (leaders) attempt to optimize the overall transportation system while road users (followers) attempt to achieve their own maximal benefit. The first part of this dissertation attempts to study NDP by combining a decomposition-based algorithmic structure with dual variable approximation techniques derived from linear programming theory. One of the critical elements in considering any real-time traffic management strategy requires assessing network traffic dynamics. Traffic is inherently dynamic, since it features congestion patterns that evolve over time and queues that form and dissipate over a planning horizon. It is therefore imperative to calibrate the DTA model such that it can accurately reproduce field observations and avoid erroneous flow predictions when evaluating traffic management strategies. Satisfactory calibration of the DTA model is an onerous task due to the large number of variables that can be modified and the intensive computational resources required. In this dissertation, the off-line DTA capacity calibration problem is studied in an attempt to devise a systematic approach for effective model calibration. Congestion pricing has increasingly been seen as a powerful tool for both managing congestion and generating revenue for infrastructure maintenance and sustainable development. By carefully levying tolls on roadways, a more efficient and optimal network flow pattern can be generated. Furthermore, congestion pricing acts as an effective travel demand management strategy that reduces peak period vehicle trips by encouraging people to shift to more efficient modes such as transit. Recently, with the increase in the number of highway Build-Operate-Transfer (B-O-T) projects, tolling has been interpreted as an effective way to generate revenue to offset the construction and maintenance costs of infrastructure. To maximize the benefits of congestion pricing, a careful analysis based on dynamic traffic conditions has to be conducted before determining tolls, since sub-optimal tolls can significantly worsen the system performance. Combining a network-wide time-varying toll analysis together with an efficient solution-building approach will be one of the main contributions of this dissertation. The problems mentioned above are typically framed as bi-level programs, which pose considerable challenges in theory and as well as in application. Due to the non-convex solution space and inherent NP-complete complexity, a majority of recent research efforts have focused on tackling bi-level programs using meta-heuristics. These approaches allow for the efficient exploration of complex solution spaces and the identification of potential global optima. Accordingly, this dissertation also attempts to present and compare several meta-heuristics through extensive numerical.
Book Synopsis Analytical Dynamic Traffic Assignment Approsches for Modelling Integrated Real-time Traffic Control Systems by : Seong-Il Shin
Download or read book Analytical Dynamic Traffic Assignment Approsches for Modelling Integrated Real-time Traffic Control Systems written by Seong-Il Shin and published by . This book was released on 2001 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Calibration of Dynamic Traffic Assignment Models with Point-to-point Traffic Surveillance by : Vikrant Suhas Vaze
Download or read book Calibration of Dynamic Traffic Assignment Models with Point-to-point Traffic Surveillance written by Vikrant Suhas Vaze and published by . This book was released on 2007 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) The estimation results are tested using a calibrated Microscopic Traffic Simulator (MITSIMLab). The results are compared to the base case of calibration using only the conventional point sensor data. The results indicate that the utilization of AVI data significantly improves the calibration accuracy.
Book Synopsis Calibration of Mesoscopic Traffic Simulation Models for Dynamic Traffic Assignment by : Kunal Kamlakar Kundé
Download or read book Calibration of Mesoscopic Traffic Simulation Models for Dynamic Traffic Assignment written by Kunal Kamlakar Kundé and published by . This book was released on 2002 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Critical Enhancements of a Dynamic Traffic Assignment Model for Highly Congested, Complex Urban Network by : Zheng Wei (S. M.)
Download or read book Critical Enhancements of a Dynamic Traffic Assignment Model for Highly Congested, Complex Urban Network written by Zheng Wei (S. M.) and published by . This book was released on 2010 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: To accurately replicate the highly congested traffic situation of a complex urban network, significant challenges are posed to current simulation-based dynamic traffic assignment (DTA) models. This thesis discusses these challenges and corresponding solutions with consideration of model accuracy and computational efficiency. DynaMITP, an off-line mesoscopic DTA model is enhanced. Model success is achieved by several critical enhancements aimed to better capture the traffic characteristics in urban networks. A Path-Size Logit route choice model is implemented to address the overlapping routes problem. The explicit representation of lane-groups accounts for traffic delays and queues at intersections. A modified treatment of acceptance capacity is required to deal with the large number of short links in the urban network. The network coding is revised to maintain enough loader access capacity in order to avoid artificial bottlenecks. In addition, the impacts of bicycles and pedestrians on automobile traffic is modeled by calibrating dynamic road segment capacities. The enhanced model is calibrated and applied to a case study network extracted from the city of Beijing, China. Data used in the calibration include sensor counts and floating car travel time. The improvements of the model performance are indicated by promising results from validation tests.
Book Synopsis Online Calibration for Simulation-based Dynamic Traffic Assignment by : Haizheng Zhang (Ph. D.)
Download or read book Online Calibration for Simulation-based Dynamic Traffic Assignment written by Haizheng Zhang (Ph. D.) and published by . This book was released on 2018 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: The severity of traffic congestion is increasing each year in the US, resulting in higher travel times, and increased energy consumption and emissions. They have led to an increasing emphasis on the development of tools for trac management, which intends to alleviate congestion by more eciently utilizing the existing infrastructure. Eective trac management necessitates the generation of accurate short-term predictions of trac states and in this context, simulation-based Dynamic Trac Assignment (DTA) systems have gained prominence over the years. However, a key challenge that remains to be addressed with real-time DTA systems is their scalability and accuracy for applications to large-scale urban networks. A key component of real-time DTA systems that impacts scalability and accuracy is online calibration which attempts to adjust simulation parameters in real-time to match as closely as possible simulated measurements with real-time surveillance data. This thesis contributes to the existing literature on online calibration of DTA systems in three respects: (1) modeling explicitly the stochasticity in simulators and thereby improving accuracy; (2) augmenting the State Space Model (SSM) to capture the delayed measurements on large-scale and congested networks; (3) presenting a gradient estimation procedure called partitioned simultaneous perturbation (PSP) that utilizes an assumed sparse gradient structure to facilitate real-time performance. The results demonstrate that, first, the proposed approach to address stochasticity improves the accuracy of supply calibration on a synthetic network. Second, the augmented SSM improves both estimation and prediction accuracy on a congested synthetic network and the large-scale Singapore expressway network. Finally, compared with the traditional finite difference method, the PSP reduces the number of computations by 90% and achieves the same calibration accuracy on the Singapore expressway network. The proposed methodologies have important applications in the deployment of real-time DTA systems for large scale urban networks.
Book Synopsis Traffic Simulation and Data by : Winnie Daamen
Download or read book Traffic Simulation and Data written by Winnie Daamen and published by CRC Press. This book was released on 2014-09-17 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: A single source of information for researchers and professionals, Traffic Simulation and Data: Validation Methods and Applications offers a complete overview of traffic data collection, state estimation, calibration and validation for traffic modelling and simulation. It derives from the Multitude Project—a European Cost Action project that incorporates work packages defining traffic simulation practice and research; highway and network modeling; and synthesis, dissemination, and training. This book addresses the calibration and validation of traffic models, and introduces necessary frameworks and techniques. It also includes viable methods for sensitivity analyses, and incorporates relevant tools for application. The book begins with a brief summary of various data collection techniques that can be applied to collect different data types. It then showcases various data processing and enhancement techniques for improving the quality of collected data. It also introduces the techniques according to the type of estimation, for example microscopic data enhancement, traffic state estimation, feature extraction and parameter identification techniques, and origin–destination matrix estimation. The material discusses the measures of performance, data error and goodness of fit, and optimization algorithms. It also contains the sensitivity analyses of parameters in traffic models. Describes the various tasks of calibration and validation Considers the best use of available data Presents the sensitivity analysis method Discusses typical issues of data error in transportation system data and how these errors can impact simulation results Details various methodologies for data collection, sensitivity analysis, calibration, and validation Examines benefits that result from the application of these methods Traffic Simulation and Data: Validation Methods and Applications serves as a key resource for transport engineers and planners, researchers, and graduate students in transport engineering and planning.
Book Synopsis Forecasting Travel in Urban America by : Konstantinos Chatzis
Download or read book Forecasting Travel in Urban America written by Konstantinos Chatzis and published by MIT Press. This book was released on 2023-07-11 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: A history of urban travel demand modeling (UTDM) and its enormous influence on American life from the 1920s to the present. For better and worse, the automobile has been an integral part of the American way of life for decades. Its ascendance would have been far less spectacular, however, had engineers and planners not devised urban travel demand modeling (UTDM). This book tells the story of this irreplaceable engineering tool that has helped cities accommodate continuous rise in traffic from the 1950s on. Beginning with UTDM’s origins as a method to help plan new infrastructure, Konstantinos Chatzis follows its trajectory through new generations of models that helped make optimal use of existing capacity and examines related policy instruments, including the recent use of intelligent transportation systems. Chatzis investigates these models as evolving entities involving humans and nonhumans that were shaped through a specific production process. In surveying the various generations of UTDM, he delves into various means of production (from tabulating machines to software packages) and travel survey methods (from personal interviews to GPS tracking devices and smartphones) used to obtain critical information. He also looks at the individuals who have collectively built a distinct UTDM social world by displaying specialized knowledge, developing specific skills, and performing various tasks and functions, and by communicating, interacting, and even competing with one another. Original and refreshingly accessible, Forecasting Travel in Urban America offers the first detailed history behind the thinkers and processes that impact the lives of millions of city dwellers every day.
Book Synopsis Handbook on Artificial Intelligence and Transport by : Hussein Dia
Download or read book Handbook on Artificial Intelligence and Transport written by Hussein Dia and published by Edward Elgar Publishing. This book was released on 2023-10-06 with total page 649 pages. Available in PDF, EPUB and Kindle. Book excerpt: With AI advancements eliciting imminent changes to our transport systems, this enlightening Handbook presents essential research on this evolution of the transportation sector. It focuses on not only urban planning, but relevant themes in law and ethics to form a unified resource on the practicality of AI use.
