Jaume Barceló

Travel time forecasting and dynamic origin-destination estimation for freeways based on bluetooth traffic monitoring

Traditional technologies, such as inductive loop detectors, do not usually produce measurements of the quality required by real-time applications. Therefore, one wonders what could be expected from newer information and communication technologies, such as automatic vehicle location, license plate recognition, and detection of mobile devices. The main objectives of this paper are to explore the quality of the data produced by Bluetooth detection of mobile devices that equip vehicles for travel time forecasting and its use in estimating time-dependent origin-destination matrices. Ad hoc procedures based on Kalman filtering have been designed and implemented successfully, and the numerical results of the computational experiments are presented and discussed.

A heuristic lagrangean algorithm for the capacitated plant location problem

Abstract Lagrangean techniques have been widely applied to the uncapacitated plant location problem, and in some cases they have proven to be successfull even when capacitated problems with additional constraints are taken into account. In our paper we study the application of these techniques to the capacitated plant location problem when the model considered is a pure integer one. Several lagrangean decompositions are considered and for some of them heuristic algorithms have been designed to solve the resulting lagrangean subproblems, the heuristics consisting of a two phase procedure. The first (location phase) defines a set of multipliers from the analysis of the dual LP relaxation, and makes a choice of the plants considering the resulting subproblems as a particular case of the general assignment problems. Several heuristics have been studied for this second phase, based either on a decomposition of knapsack type subproblems through a definition of a set of penalties, or of looking into the duality gap and trying to reduce it. Computational experience is reported.

Model-Based Systems Engineering: An Emerging Approach for Modern Systems

To engineer the modern large, complex, interdisciplinary systems-of-systems (SoS), the collaborative world teams must “speak” the same language and must work on the same “matter.” The “matter” is the system model and the communication mechanisms must be supported by standard, flexible, and friendly modeling languages. The evolving model-based systems engineering (MBSE) approach is leading the way and is expected to become a standard practice in the field of systems engineering (SE) in the next decade. As an emerging paradigm for the systems of the 21st century, it seems useful to overview its current state of the art concerning the developing standards, the embryonic formalisms, the available modeling languages, the methodologies, and the major applications.

Parallelization of Microscopic Traffic Simulation for Att Systems Analysis

Simulation is a process based on building a computer model that suitably represents a real or proposed system which enables to extract valid inferences on the behavior of the modeled system, from the outcomes of the computer experiments conducted on its model. Simulation has become in recent years one of the most used and powerful tools for systems analysis and design, by its proven ability to answer “what if” questions helping the system designer to find solutions for building new systems, or assess the impact of proposed changes on an already existing system. A simulation model is always a simplified representation of a system that addresses specifically those aspects of the studied system relevant for the purposes of the analysis from the point of view of the system analyst. A simulation model is therefore specific, both for the problem and for whoever tries to use the model for finding solutions to the problem. A simulation study has usually the objective of helping to get a better understanding on how a system behaves, evaluating the impact of changes in the system, or in values of the parameters governing the system, or of decisions on the policies controlling the system.

A simulation study of the fleet sizing problem arising in offshore anchor handling operations

A fleet sizing problem arising in anchor handling operations related to movement of offshore mobile units is presented in this paper. Typically, the intensity of these operations is unevenly spread throughout the year. The operations are performed by dedicated vessels, which can be hired either on the long-term basis or on the spot market. Spot rates are frequently a magnitude higher than long-term rates, and vessels are hired on the spot market if there is a shortage of long-term vessels to cover the ongoing anchor handling operations. Deciding the cost-optimal fleet of vessels on the long-term hire to cover future operations is a problem facing offshore oil and gas operators. This decision has a heavy economic impact as anchor handling vessels are among the most expensive ones. The problem is highly stochastic because durations of anchor handling operations vary and depend on uncertain weather conditions. Moreover, future spot rates for anchor handling vessels are extremely volatile. The objective of this paper is to describe a simulation model for the fleet sizing problem. The study was initiated by the largest Norwegian offshore oil and gas operator and has received considerable acceptance among the planners.

Models, Traffic Models, Simulation, and Traffic Simulation

This introductory chapter to a book on traffic simulation fundamentals is aimed at setting up a comprehensive framework for simulation as a well-established and grounded OR technique and its specificities when applied to traffic systems; the main approaches to traffic simulation and the principles of traffic simulation model building; the fundamentals of traffic flow theory and its application to traffic simulation from macroscopic, mesoscopic, or microscopic approaches. The chapter also provides a basic overview on the principles of dynamic traffic assignment and its application to traffic simulation and the calibration and validation of traffic simulation models, two key topics to establish the validity and credibility for traffic simulation models being used in the decision-making processes.

Adjustment of O-D trip matrices from observed volumes: An algorithmic approach based on conjugate directions

Abstract This paper presents a new algorithmic alternative to the O–D matrix adjustment problem from observed link volumes when it is formulated as a mathematical programming problem with a bilevel structure. The algorithmic approach presented is based on a method for nondifferentiable optimization due to Wolfe that can be interpreted as a conjugate directions method with better convergence properties as shown with a set of computational tests. Closely related to the algorithm presented, the problem of approximating gradients of the upper level function is discussed and a new and consistent approach is presented and analyzed with a detailed description of the algorithmic aspects involved.

Traffic Data Collection and Its Standardization

Traffic engineers are involved in transport modeling, traffic simulation, operation optimization, and the development of methods to control and analyze traffic itself. New developments of individual traffic, public transport as well as pedestrian movements are the hope to ensure mobility and accessibility in urban areas to secure mobility in the less profitable countryside, to increase safety, and to limit the effects on the environment caused by transportation. Around the globe, governments declare goals in each of the mentioned fields, mostly under the umbrella of intelligent transport systems (ITS) to develop a sustainable transportation for everyone.

Traffic Simulation: Case for guidelines

The MULTITUDE Project (Methods and tools for supporting the Use, caLibration and validaTIon of Traffic simUlations moDEls) is an Action (TU0903) supported by the EU COST office (European Cooperation in Science and Technology) and focuses on the issue of uncertainty in traffic simulation, and of calibration and validation as tools to manage it. It is driven by the concern that, although modelling is now widespread, we are unsure how much we can trust our results and conclusions. Such issues force into question the trustworthiness of the results, and indeed how well we are using them.

A Kalman filter approach for exploiting bluetooth traffic data when estimating time-dependent OD matrices

Time-dependent origin–destination (OD) matrices are essential input for dynamic traffic models such as microscopic and mesoscopic traffic simulators. Dynamic traffic models also support real-time traffic management decisions, and they are traditionally used in the design and evaluation of advanced traffic traffic management and information systems (ATMS/ATIS). Time-dependent OD estimations are typically based either on Kalman filtering or on bilevel mathematical programming, which can be considered in most cases as ad hoc heuristics. The advent of the new information and communication technologies (ICT) provides new types of traffic data with higher quality and accuracy, which in turn allows new modeling hypotheses that lead to more computationally efficient algorithms. This article presents ad hoc, Kalman filtering procedures that explicitly exploit Bluetooth sensor traffic data, and it reports the numerical results from computational experiments performed at a network test site.