Recently a methodology for traffic networks has been developed which extracts congestion toll sets such that the tolled user equilibrium is system optimal. Properties of toll sets, such as convexity, are investigated, as well as relationships with other problems. For a given toll set, various objectives can be defined and optimized with respect to the tolls. Examples include minimizing the total tolls collected, minimizing the number of toll booths and constraining net tolls collected to be zero. We illustrate with an example and report on our computational experience with the Stockholm network.

In this paper we present a version of the (static) traffic equilibrium problem in which the cost incurred on each path is not simply the sum of the costs on the arcs that constitute that path. We motivate this nonadditive version of the problem by describing several situations in which the classic additivity assumption fails. We describe existence and uniqueness conditions for this problem and we also present convergence theory for a generic algorithm for solving nonadditive problems. INTRODUCTION Paraphrasing Wardrop [33], the (static) traffic equilibrium problem is to find a set of path flows that satisfy certain demand constraints and have the property that the costs on all used paths connecting an origin-destination pair are equal and less than or equal to the cost on all unused paths connecting that pair. In order to prove existence/uniqueness results and develop convergent algorithms, this problem has been formulated as a nonlinear program (NLP) [4], a nonlinear complementarity...

We consider multiobjective shortest paths, a fundamental (NP-hard) problem in multiobjective optimization, where we are interested not in optimizing a single objective, but in finding a set of paths that captures the trade-off (the so-called Pareto curve) among several objectives in a digraph whose edges are associated with multidimensional cost vectors. We provide a new FPTAS for computing an approximate Pareto curve for multiobjective shortest paths that significantly improves upon previous approaches, especially in the case of more than two objective functions. We show how our new FPTAS can be used to provide better approximate solutions to three related problems (multiobjective constrained optimal paths, multiobjective constrained paths, and non-additive shortest paths) that have important applications in the areas of quality of service routing in communication networks, and in computing traffic equilibria in transportation networks. We also show how our new FPTAS for multiobjective shortest paths can provide efficient approximate solutions in a completely different context – to a natural generalization of the weighted multicommodity flow problem with elastic demands and values that models several realistic design scenarios in transportation and communication networks. Finally, as a byproduct of our framework, we provide a generic method for constructing FPTAS for any multiobjective optimization problem with non-linear objective functions of a rather general form.

Abstract: In this paper, we develop an evolutionary variational inequality model of the Internet with multiple classes of traffic and demonstrate its utility through the formulation and solution of a time-dependent Braess paradox. The model can handle time-dependent changes in demand as a consequence of developing news stories, following, for example, natural disasters or catastrophes or major media events. The model can also capture the 1 time-varying demand for Internet resources during a regular weekday with its more regular rhythm of work and breaks. In addition, the model includes time-varying capacities on the route flows due to, for example, government interventions or network-type failures. 2 1.

This paper presents the functionality of the Visual Interactive System for Transportation Algorithms (VISTA) that utilizes a mesoscopic/microscopic simulation called RouteSim and a Dynamic Traffic Assignment (DTA) routine to emulate the behavior of individual drivers and how they distribute themselves into the transportation network. The principal output of the model is the path chosen by every driver to go from their origin to their destination, and the corresponding departure and arrival time. The paper presents the application of VISTA to evaluate: 1) Intelligent Transportation technologies such as the location of variable message signs, detectors, route diversion plans; 2) Traffic Operations such as signal timing plans, transit signal priority plans, flooding, weather conditions; and 3) Short term and Long term transportation planning such as construction plans, addition/deletion of lanes or roadways, addition or improvement of roadway interchanges. A sample of projects where VISTA has been implemented in the USA is presented.

This report describes the methodologies and procedures developed through a contract to the University of Texas at Austin, in collaboration with the University of Maryland, to address these essential needs. Specifically, a simulation-assignment methodology has been developed to describe user's path choices in the network in response to real-time information, and the resulting flow patterns that propagate through the network, yielding information about overall quality of service and effectiveness, as well as localized information pointing to problem spots and opportunities for improvement. This methodology is intended for use off-line for evaluation purposes, or on-line for prediction purpose in support of advanced traffic management functions. In additional, algorithmic procedures have been developed to determine the best paths to which users should be directed so as to optimize overall system performance. Powerful extension

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This paper describes the impact and influence of the book, Studies in the Economics of Transportation, by M. J. Beckmann, C. B. McGuire, and C. B. Winsten, published in 1956 by Yale University Press. The focus of this paper is on the book’s impacts on innovations in modeling, methodological developments, and applications in transportation science and in other disciplines as well.

Earthquakes damage freeway bridges and structures, resulting in significant impacts on transportation system performance and regional economy. The California Department of Transportation (Caltrans) has developed bridge seismic retrofit programs that include seismic risk analysis (SRA) procedures for structural re-enforcement projects. CaltransÕ SRA procedure establishes retrofit priorities for vulnerable highway bridges. Existing SRA procedures use average daily traffic (ADT) volumes to determine the importance of a bridge. This is not adequate. The importance of network links should be evaluated in terms of the system cost of failure. Incorporation of an efficient transportation modeling technology in the SRA procedures is essential. The objectives of this research are: (1) to develop an efficient transportation network analysis (TNA) procedure for many different traffic flow analyses under numerous scenario earthquakes, and (2) to evaluate the applicability of the procedure to a large-scale transportation network. An important feature of the TNA procedure is the use of an associative memory (AM) approach as a cost-effective means in network flow modeling. The AM approach is a heuristic method

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