Giuseppe Bruno

A multi-modal approach to the location of a rapid transit line

Abstract The location of a rapid transit line (RTL) represents a very complex decision problem because of the large number of decision makers, unquantifiable criteria and uncertain data. In this context Operational Research can help in the design process by providing tools to generate and assess alternative solutions. For this purpose two bicriterion mathematical programming models — the Maximum Coverage Shortest Path model and the Median Shortest Path model — have been developed in the past. In this paper a new bicriterion model, which can evaluate in a more realistic way the attractivity of an RTL is introduced. To calculate an estimation of the non-inferior solution set of the problem, a procedure based on a k -shortest path algorithm was developed. This approach was applied to a well-known sample problem and the results are discussed and compared with those obtained using a Median Shortest Path model.

A heuristic for the location of a rapid transit line

Abstract This article presents a mathematical model and a two-phase heuristic for the location of a rapid transit alignment in an urban setting. This method can be viewed as a building block for the multi-line network design problem. Computational results on randomly generated instances and on some Milan real data confirm the efficiency of the proposed approach. Scope and purpose When designing rapid transit lines, a common objective is the maximization of the toal population covered by the alignment, subject to interstation spacing constraints. This article describes an efficient and robust heuristic for generating good alignments. These can then be assessed according to other criteria before a final decision is made.

Using gravity models for the evaluation of new university site locations: A case study

A fundamental aspect of competitive spatial models is the choice behaviour of potential customers to patronize a facility. Most of the models used to describe this phenomenon are essentially based on the adaptation of Newtons law of gravitation to the economic case (gravity model). This paper shows an application of this model to describe the behaviour of potential students in the choice of a university site. The results provided by the model have been compared with the actual data and show that the gravity model can describe the behaviour of potential students with good approximation.

Dynamic positioning of idle automated guided vehicles

An automated guided vehicle (AGV) is a mobile robot commonly used to carry loads in material handling systems (MHS). Once a transfer is completed, an AGV stops at a home position, a point where it can park until it is assigned a new task. Determining the home positions is an important control problem with a direct influence on the overall performance of the MHS. The problem can be viewed as a location-allocation problem on a network. In this paper two fast and effective heuristics which dynamically determine the home positions are proposed. The methods were tested using two real-world instances. The obtained results are shown and discussed.

Models for the schedule optimization problem at a public transit terminal

This work deals with the proposal of some models for the schedule optimization problem for public transit networks. In particular, we consider the case of a transit terminal where passengers are supposed to split among different lines of a service, or even change mode of transportation in case of intermodal systems. Starting from a given schedule for the transit lines arriving at the terminal, the aim is to decide the optimal schedule for the output lines, in such a way to balance the operative costs of the service and the passenger waiting time at the transit terminal. We propose two different models for this problem, which present strong similarities with some well known combinatorial optimization models. Computational results are also presented, showing the suitability of the models to solve real case studies.

An Interactive Decision Support System For The Design Of Rapid Public Transit Networks

Abstract This article describes a visual interactive decision support system for the simultaneous location of several rapid transit lines in a city. Three types of tool are available to the user: parameter setting, menu choices, and mouse operations. The system produces network configurations of the type selected by the user and computes a number of effectiveness measures. The system has been tested on real data from the city of Milan, Italy. It can consistently produce several interesting alternative solutions within short computing times.

ANALYSIS OF PUBLIC E-PROCUREMENT WEB SITE ACCESSIBILITY

A vast amount of literature has highlighted that accessibility is becoming crucial in evaluating e-procurement web site effectiveness. In this context, this paper shows some results of multidisciplinary research whose aim is to identify a model to evaluate e-procurement web site accessibility. The specific goal is to identify a group of web site attributes and characteristics that can be measured using quantitative indicators. For this purpose, a model based on a three-level hierarchical system has been introduced. The proposed model has been used to evaluate three Italian public e-procurement web sites. Finally, the conclusions and some indications on future developments of research are illustrated.

An extension of the schedule optimization problem at a public transit terminal to the multiple destinations case

We present a mathematical model to optimize the number of output lines leaving from a transit terminal (in which passengers are supposed to split among different lines, or even change mode of transportation) and their departure times in the aperiodic case. The model is an extension to the multiple destination case of the Schedule Optimization Problem described in (Bruno et al. in OR Spectr. 31(3):465–481, 2009). The proposed model is shown to be NP-hard due to its similarities to the Multi-Item Capacitated Lot Sizing Problem. We provide computational results in order to show that the model can be used to solve instances of significant size.

Routing problems: a historical perspective

This paper presents an historical perspective on routing problems. Today a well-established class of optimization problems, routing problems have played a pivotal role in the development of Logistics as a discipline, even influencing other sectors not directly connected to management studies. The aim of this paper is to provide an overview of the evolution of this topic, starting from seminal contributions by Euler and Hamilton, and illustrating the most recent applications. This article is based on a longer article originally published in Italian (Bruno et al. 2010).

Individual controlled junctions: Optimal design

Abstract The phase-based approach is a recent evolution in the field of undersaturated isolated junction control optimization. Using the incompatibilities among the streams, it proceedes calculating the control variable values without the external individuation of a stage matrix. One of these methods, based on a binary linear mathematical model, performs the simultaneous optimization of cycle time, green splits and green scheduling. The model, however, requires a preliminary decision about the composition of the streams and their assignment to the lanes. The flow ratios of the streams, indeed, have to be supposed constant during the cycle. In this paper an idea to remove this last hypothesis is described. It is based on a simple model regarding the behaviour of the users belonging to streams coming from the same access. A numerical example using a test junction is shown; the obtained results are compared to the ones deriving from a standard phase-based method.