António Pais Antunes

Optimal Location of Charging Stations for Electric Vehicles in a Neighborhood in Lisbon, Portugal

Growing concerns about environmental issues have led to the consideration of alternatives to current mobility. Electric mobility is one such alternative that is receiving a great deal of attention in Europe. In particular, a new legal framework for the introduction of an electric mobility system in Portugal has recently been set up by the government. A key issue in this system is recharging the batteries and, consequently, the location of charging stations. This paper presents a study on the location of electric-vehicle charging stations for an area of Lisbon, the capital city of Portugal, characterized with a strong concentration of population and employment. This type of area is appropriate for slow charging because vehicles stay parked for several hours within a 24-h period. The methodology used here is based on a maximal covering model to optimize the demand covered within an acceptable level of service and to define the number and capacity of the stations to be installed. The results clearly indicate that this methodology can be useful in the future planning of electric mobility systems.

Recyclable waste collection planning--a case study

Abstract This paper describes a study of planning vehicle routes for the collection of urban recyclable waste. The aim is to create collection routes for every day of the month, to be repeated every month, minimizing the operation cost. Two important features of the problem are the planning of a relatively long period of time and the separate collection of three types of waste. The collection operation was modelled in accordance to the practice of the company that manages the collection system. Heuristic techniques were developed to solve the model in three phases: definition of the geographic zones served by the vehicles, definition of the waste type to collect on each day of the month, definition of the collection routes. Preliminary results suggest that significant economies in collection costs are possible.

A hierarchical location model for public facility planning

In this article, we present a discrete hierarchical location model for public facility planning. The main features of the model are: an accessibility maximization objective; several levels of demand and of facilities; a nested hierarchy of facilities (i.e. a facility of a given level can serve demand of equal and lower levels); maximum and minimum capacity constraints; and user-to-facility assignment constraints. The latter include single-assignment and closest-assignment constraints, as well as a new type of constraints called path-assignment constraints. Their purpose is to enforce some desirable properties for the spatial pattern of assignments. If they are not included, model solutions are difficult to interpret and to explain in a public facility planning context, therefore being less likely to be accepted by the users. The usefulness of the model is illustrated through a real-world application to school network planning. 2007 Elsevier B.V. All rights reserved.

On solving complex multi-period location models using simulated annealing

This paper describes a study aimed at evaluating the capabilities of simulated annealing in dealing with complex, real-world multi-period location problems raised by school network planning in Portugal. The problems were formulated as mixed-integer linear optimization models. The models allow for facility closure or size reduction besides facility opening and size expansion, with sizes possibly limited to a set of pre-defined standards. They assume facility costs to be divided into a fix component and two variable components, respectively dependent on facility size and facility attendance. Results obtained through the study indicate that simulated annealing can be a useful tool for solving these kinds of models.

Integrating Equity Objectives in a Road Network Design Model

The traditional approach to the road network design problem focuses on the optimization of network efficiency under a given budget. Generally, this leads to the improvement of roads next to the largest population centers, where travel demand is higher. Such results are not consistent with sustainable development principles, since the dissimilarities between the welfare of large and small centers will tend to increase. Nevertheless, equity issues were rarely taken into account in road network design. Moreover, all existing studies rely on a single equity measure. In this paper equity concerns in transportation planning are reviewed briefly, and a comparison of alternative equity measures is presented. Three equity measures were selected and incorporated into an accessibility-maximization road network design model. The three equity measures reflect different perspectives on equity: accessibility to low-accessibility centers, the dispersion of accessibility values across all centers (Gini coefficient), and the dispersion of accessibility values across all centers and across centers in the same region (Theil index). The implications of adopting each of these equity measures are illustrated through application of the optimization model to three random networks.

An Accessibility–Maximization Approach to Road Network Planning

Accessibility, is a key, factor in defining the quality, of life and potential for development of both cities and regions. This article presents a new accessibility maximization approach to inter-urban road network long-term planning. The approach is based on a nonlinear combinatorial optimization model. Two heuristics have been developed for solving the model, based on local search and,simulated annealing principles, respectively. The efficiency, of the heuristics was evaluated on a sample of test problems involving 10-, 20-, and 40-node networks. In the analysis both solution quality and computing effort were taken into account. The approach was used to analyze the ongoing transformation of the Portuguese main road network. The results obtained so far indicate that the model is a valuable decision-aid tool for inter-urban road network long-term planning.

A segment-linked optimization model for deterministic pavement management systems

This paper presents a segment-linked optimization model to be used within deterministic pavement management systems. The model is aimed at determining the least-cost maintenance and rehabilitation strategy to be implemented in a road network, taking into account the applicable technical and budgetary constraints. The evolution of pavements with regard to cracking, rutting, surface disintegration, and longitudinal roughness is estimated with deterministic performance models. The overall quality of pavements is assessed through a modified version of the Present Serviceability Index (PSI). The method developed to solve the model is based on genetic algorithm principles. The application of the model is illustrated for a case study involving the road network of Coimbra, the third-largest Portuguese city. The results obtained for this case study indicate that the model is a valuable addition to the road engineers toolbox.

Interurban road network planning model with accessibility and robustness objectives

Abstract Road network planning (or design) problems consist of determining the best investment decisions to be made with regard to the improvement of a road network. In this paper, we propose an optimization model for long-term interurban road network planning where accessibility and robustness objectives are simultaneously taken into account. Three network robustness measures were defined to assess different robustness concerns: network spare capacity; city evacuation capacity; and network vulnerability. The results that may be obtained from the application of the model are illustrated for three random networks. Special attention is given to the implications of adopting each one of the robustness measures upon the optimum solution provided by the model.

Optimal Location of Railway Stations: The Lisbon-Porto High-Speed Rail Line

Rail transportation has experienced a rebirth in the last few decades, and a very large investment will certainly be made in new railway lines in the years to come---especially in high-speed rail lines. The success of such investment is heavily dependent on rail ridership, which in turn is dependent on the location of railway stations. In this paper, we present a mixed-integer optimization model that determines the optimal location and number of stations along a railway line that will be introduced over an existing transportation network. The stations are chosen within a set of possible locations defined a priori according to the objective of maximizing travel cost savings. The model takes into account the sensitivity of rail ridership to time losses because of stops at intermediate stations, as well as static competition from other modes. The practical usefulness of the model is illustrated with a case study involving a high-speed rail line expected to be built in Portugal in the future: the Lisbon-Porto line.

Multiobjective Approach to Long-Term Interurban Multilevel Road Network Planning

This article presents a multiobjective approach to long-term interurban multilevel road network planning. In addition to the efficiency objectives dealt with in most of the literature where the subject is addressed, the approach takes into account robustness and equity objectives. For achieving the objectives, two types of action can be performed: the construction of a new road of a given level; and the upgrading of an existing road to a higher level. The approach is consistent with the planning framework of the highway capacity manual, using the concept of level of service to assess traffic flow conditions. The application of the approach is illustrated for a case study involving the main road network of Poland.