Dynamic Traffic Assignment

Network user equilibrium or user optimum is an ideal state that can hardly be achieved in real traffic. More often than not, every day traffic tends to be in disequilibrium rather than equilibrium, thanks to uncertainties in demand and supply of the network. In this paper we propose a hybrid route choice model for studying non-equilibrium traffic. It combines pre-trip route choice and en-route route choice to solve dynamic traffic assignment (DTA) in large-scale networks. Travelers are divided into two groups, habitual travelers and adaptive travelers. Habitual travelers strictly follow their pre-trip routes which can be generated in the way that major links, such as freeways or major arterial streets, are favored over minor links, while taking into account historical traffic information. Adaptive travelers are responsive to real-time information and willing to explore new routes from time to time. We apply the hybrid route choice model in a synthetic medium-scale network and a large-scale real network to assess its effect on the flow patterns and network performances, and compare them with those obtained from Predictive User Equilibrium (PUE) DTA. The results show that PUE-DTA usually produces considerably less congestion and less frequent queue spillback than the hybrid route choice model. The ratio between habitual and adaptive travelers is crucial in determining realistic flow and queuing patterns. Consistent with previous studies, we found that, in non-PUE DTA, supplying a medium sized group (usually less than 50%) of travelers real-time information is more beneficial to network performance than supplying the majority of travelers with real-time information. Finally, some suggestions are given on how to calibrate the hybrid route choice model in practice to produce realistic results.

Traffic signal setting is an important element in traffic planning of urban road networks in ordinary conditions and/or in emergency conditions. As traffic signal setting affects user behaviour mainly at the path choice dimension, this dependence has to be studied by means of assignment models. We thus present a system of models and procedures for signal setting optimization with assignment of travel demand to a congested road transport network. Two interacting procedures are developed to solve the system of models: (i) an optimization procedure to obtain an optimal configuration of signal setting parameters and (ii) an assignment procedure, incorporating a path choice model with explicit path enumeration and a flow propagation model, to capture the effects of signal setting configuration on user path choice behaviour. The system of models and procedures is applied and validated on a real test site, where the transport system is in dynamic conditions due to the time-varying road network and travel demand. The test site is a portion of a small-size town where the population needs to be evacuated due to an imminent calamitous event. The results show considerable reductions in total delays on the network and evacuation times in the case of optimized signal setting parameters.

The assignment – selection problem used to find one-to- one match of given “Users” to “Laptops”, the main objective is to minimize the cost as per user requirement. This paper presents satisfactory solution for real assignment – Laptop selection problem using MATLAB coding.

The assignment – selection problem used to find one-to-one match of given " Users " to " Laptops " , the main objective is to minimize the cost as per user requirement. This paper presents satisfactory solution for real assignment – Laptop selection problem using MATLAB coding. KEYWORD Assignment problem, linear integer programming, Revised Ones Assignment Method (ROA), MATLAB programming 2010 Mathematics Subject Classification: 90-02,

This paper presents a simple representation of traffic on a highway with a single entrance and exit. The representation can be used to predict traffic's evolution over time and space, including transient phenomena such as the building, propagation and dissipation of queues. The easy-to-solve difference equations used to predict traffic's evolution are shown to be the discrete analog of the differential equations arising from a special case of the hydrodynamic model of traffic flow. The proposed method automatically generates appropriate changes in density at locations where the hydrodynamic theory would call for a shockwave; i.e. a jump in density such as those typically seen at the end of every queue. The complex side calculations required by classical methods to keep track of shockwaves are thus eliminated. The paper also shows how the equations can mimic the real-life development of stop-and-go traffic within moving queues. The model predicts that the oscillation patter...

The fact that road transportation negatively affects the quality of the environment and deteriorates its bearing capacity has drawn a wide range of concerns among researchers. In order to provide more realistic traffic data for estimations of environmental impacts, dynamic traffic assignment (DTA) models have been adopted in transportation planning and traffic management models concerning environmental sustainability. This review summarizes and examines the recent methodological advances of DTA models in environmentally sustainable road transportation applications including traffic signal control concerning vehicular emissions and emission pricing. A classification of emission estimation models and their integration with DTA models are accordingly reviewed as supplementary to the existing reviews. Finally, a variety of future research prospects of DTA for environmentally sustainable road transportation research are discussed. In particular, this review also points out that at present the research about DTA models in conjunction with noise predictive models is relatively deficient.

The need to simulate a number of advanced ITS concepts prior to deployment has also necessitated development of high performance microscopic simulators for estimating dynamic traffic assignment, freeway corridor diversion, as well as evaluating driver information systems (including variable message signs), vehicle guidance systems, real time adaptive traffic control strategies and other traffic management concepts. The high performance microscopic simulators

The focus of this paper is on the development of an origin–destination (O-D) demand estimation method for dynamic equilibrium traffic networks. It is hypothesized that the underlying equilibrium conditions in such networks are a compromise result of minimization of individual routing costs, minimization of traffic count matching errors, and maximization of O-D demand entropies. By adding an upper bound of travel demand and a dummy path with constant travel cost to each O-D pair, we formulated the dynamic O-D demand estimation problem as an excess-demand dynamic traffic assignment (DTA) problem defined for an expanded network with dummy paths. Such a formulation enables us to apply existing DTA solution methods and software tools for deriving the path flow pattern in the expanded network and thus simultaneously obtaining the O-D demand pattern in the original network. Following this problem transformation and network expansion strategy, an iterative solution procedure is accordingly proposed, which resorts to repeatedly solving the excess-demand DTA problem and adjusting the dummy path costs. An application of the proposed modeling and solution methods for an example cell-based network problem favorably illustrates great promise of the methodological advance and solution performance.

Shashi Deshpande has numerous symbols. In intellectual debates, she defends the reasons for English as an Indian language and fights for the recognition of a woman as a person. She talks about the truth delicately yet solidly, her words lingering long after her exit. The current paper expands on the true story of women, who represent themselves or the entire womankind in a way that is not quite the same as a man telling a woman's story; additionally, it highlights the possibility of women elucidating themselves and emerging from the case of self-negligible to spread their wings of selfassurance. The current study, based on Shashi Deshpande's selected novels, deals with the complexities of man-woman relationships, particularly in the context of marriage, as well as the trauma of disturbed adolescence, with reference to four novels by Shashi Deshpande, namely That Dark Holds No Terrors (1980), Binding Vine That Long Silence A Matter Of Time and Shadows Remedies, Penguin India (2000), On, Penguin She depicts what happens to men and women in and after marriage, what they have been, what they have become and what is in store for them. The changes in the status of men and women after marriage and the changing nature of marital relationships are presented in these four novels. Focusing on marital relations, she seeks to expose the tradition by which a woman is trained to play her subservient role in the family. Shashi Deshpande’s novels also show how carefully she expresses the frustration and disappointment of women, which they experience in their marital relationships. It implies that men and women must work together to create a mature and balanced gender relationship.

Dieser Beitrag stellt Ansätze und Prinzipien der umweltorientierten Verkehrsmodellierung zur Diskussion. Am Beispiel von Verkehrsumlegungsmodellen wird aufgezeigt, wie in einem praktischen Fall der systematische Vergleich konkurrierender Modelle mehr zum Erkenntnisgewinn beitragen kann als die Verwendung eines einzelnen Modells. Diese Vorgehensweise wird unterstützt durch eine Modellbank für die umweltorientierte Verkehrsmodellierung. die im Rahmen des MOBILE-Projekts am Fachbereich Informatik der Universität Hamburg aufgebaut wird.

Evacuation plans are traditionally based on empirical knowledge and local experience. Many studies are underway to improve and, even, optimize the process of evacuation planning and operations. To this end, a commonly accepted set of well-defined measures of effectiveness (MOEs) for evacuation is necessary. To guide various optimization processes and assess their benefits, this paper examines MOEs in literature, whether implicitly assumed or explicitly defined, and subsequently proposes a comprehensive four-tier MOE framework, taking into consideration of evacuation time, cumulative exposure, and temporal/spatial risk factors. For each tier of MOE, the optimization formulation is presented.

This paper describes a decision support system (DSS) for the design and evaluation of service integrated systems (bus-bus and/or railway-bus) at regional scale. The modelling system has been built through a "what if' approach by using a system of schedule-based supply, demand and demand-supply interaction models; these models have been implemented in a software tool called DY -RT (DYnamic Regional Transit). The use of a within-day dynamic schedule-based
approach allows us to evaluate on-board flows and level of service
attributes (especially interchange times) for each run of each line, in order to assess in a more detailed way the effect of service integration and timetable synchronisation for regional transit networks, as described in the application examples reported in the final part of the paper.

Non-recurrent congestion is a major problem in traffic networks that causes unexpected delays during travels. This type of congestion is primarily caused due to stochasticity associated with travel demand and network supply. In such a scenario , it is preferable to use adaptive paths or policies where next link decisions on reaching junctions are continuously adapted based on information gained with time. When there is no incentive for users to change their strategies, an equilibrium is reached. In this paper, we study a traffic assignment problem in stochastic time dependent networks. The problem is modeled as a fixed point problem and existence of the equilibrium solution is discussed. We iteratively solve the problem using the Method of Successive Averages (MSA). A novel network loading model inspired from Link transmission model is developed that accepts policies as inputs for solving the problem. This network loading model is different from the existing network loading models that take predefined paths for input flows. We demonstrate through numerical tests that solving traffic assignment problem with the proposed loading modeling scheme is more efficient as compared to solving the problem using path based network loading models. In addition, the developed model captures traffic realism by modeling link spillovers and shock-wave propagation through LWR kinematic wave theory. Also, we generate a fixed number of policies in each iteration of MSA algorithm where the first policy is optimal and the remaining policies are suboptimal. We propose an algorithm to generate suboptimal policies through which the quality of generated suboptimal policies can be controlled. We show the relevance of the developed suboptimal policy algorithm by proving that the optimal policy is always allocated the largest traffic flow. As a consequence, traffic flow proportion corresponding to the optimal policy can be controlled by suitably varying a parameter in the proposed suboptimal policy generation algorithm.

In metropolitan cities, rapidly increased new construction development activities and every new development has its own traffic impact which can be affect the surrounding road network. In this research we study the systematic method to analyze traffic impact of a new construction development which can generate and attract traffic demand around the road network according to survey and analysis of existing traffic condition. To analyze, Regression method is used; evaluation of traffic growth rate is done according to past traffic data and forecast future traffic condition after development in terms of Level of service (LOS) of road. The distribution of traffic volume orderly to make sure the balance of the project won't affect the existing traffic condition. The traffic impact analysis can help to forecast the traffic volume activities for later on years, basically to investigate the different traffic elements having sway on movement conditions after improvement. Traffic assignment is involving the pattern, which is generated traffic will be distributed on according to residual capacity of surrounding roads. The traffic impact research can help to detect projected traffic condition, thus planning is made to provide facilities to minimize the traffic problems after complete commercial developments. An attempt has been done to reduce the traffic impact be mitigated by staggered office timing and carpooling 30% reduced generation and attraction traffic of Corporate Park, Carpooling introducing some AC buses and transportation facilities. Due to staggered office timing and carpooling have been observed and the traffic volume will be diverted to the proposed transportation amenities constructed which is front of study area thus the traffic condition will be reduced and LOS will be improved.

To fully understand and predict travel demand and traffic flow, it is necessary to investigate what drives people to travel. The analysis should examine why, where and when various activities are engaged in, and how activity engagement is related to the spatial and institutional organization of an urban area. In view of this, two combined activity/travel choice models are presented

This paper analyzes dynamic user equilibrium (DUE) that incorporates the notion of boundedly rational (BR) user behavior in the selection of departure times and routes. Intrinsically, the boundedly rational dynamic user equilibrium (BR-DUE) model we present assumes that travelers do not always seek the least costly route-and-departure-time choice. Rather, their perception of travel cost is affected by an indifference band describing travelers’ tolerance of the difference between their experienced travel costs and the minimum travel cost. An extension of the BR-DUE problem is the so-called variable tolerance dynamic user equilibrium (VT-BR-DUE) wherein endogenously determined tolerances may depend not only on paths, but also on the established path departure rates.

This paper presents a unified approach for modeling both BR-DUE and VT-BR-DUE, which makes significant contributions to the model formulation, analysis of existence, solution characterization, and numerical computation of such problems. The VT-BR-DUE problem, together with the BR-DUE problem as a special case, is formulated as a variational inequality. We provide a very general existence result for VT-BR-DUE and BR-DUE that relies on assumptions weaker than those required for normal DUE models. Moreover, a characterization of the solution set is provided based on rigorous topological analysis. Finally, three computational algorithms with convergence results are proposed based on the VI and DVI formulations. Numerical studies are conducted to assess the proposed algorithms in terms of solution quality, convergence, and computational efficiency.

This paper discusses a dynamic evacuation network optimization problem that incorporates lane reversal and crossing elimination strategies. These two lane-based planning strategies complement one another by increasing capacity in specific directions through the evacuation network. A bi-level network optimization model is formulated, in which the upper level aims at optimizing the network evacuation performance subject to the lane-reversal and crossing-elimination constraints and the lower level conveys a cell transmission-based dynamic traffic assignment problem. An integrated Lagrangian relaxation and tabu search method is devised for approximating optimal problem solutions through an iterative optimization-evaluation process. The numerical results of implementing the developed modeling and solution approach to a synthetic network and a real-world example application justify its theoretical and practical value.

Dynamic user equilibrium (DUE) is the most widely studied form of dynamic traffic assignment, in which road travelers engage in a non-cooperative Nash-like game with departure time and route choices. DUE models describe and predict the time-varying traffic flows on a network consistent with traffic flow theory and travel behavior. This paper documents theoretical and numerical advances in synthesizing traffic flow theory and DUE modeling, by presenting a holistic computational theory of DUE with numerical implementation encapsulated in a MATLAB software package. In particular, the dynamic network loading (DNL) sub-problem is formulated as a system of differential algebraic equations based on the fluid dynamic model, which captures the formation, propagation and dissipation of physical queues as well as vehicle spillback on networks. Then, the fixed-point algorithm is employed to solve the DUE problems on several large-scale networks. We make openly available the MATLAB package, which can be used to solve DUE problems on user-defined networks, aiming to not only help DTA modelers with benchmarking a wide range of DUE algorithms and solutions, but also offer researchers a platform to further develop their own models and applications. Updates of the package and computational examples are available at https://github.com/DrKeHan/DTA.