Important events, such as the foreseen Expo due in Milano in 2015, pose challenging logistic problems to the organization. The additional demand of transportation will often add on already congested situations that characterize most of our cities. At the same time, though, the duration of such events is limited in time, so that it does not justify consistent investments in building permanent infrastructures that would not be exploited beyond the terms of the specific event. Flexible transportation services can offer an alternative solution to such problems, since they require light infrastructure and can be easily reconverted once the event is over. Moreover, the demand is only partially foreseable so that any candidate system should be able to quickly adapt to the revealed demand without further planning. Several types of flexible transport systems exists, however there is not an assessed methodology for their planning and management. In this paper we refer to a previously studied demand adaptive system, namely DAS, and we propose a thorough approach that encompass the design of the lines and their operation, exploiting optimization techniques based on mathematical programming for solving the decision problem that arise at each step. Demand-adaptive transit systems (DAS) display features of both traditional fixed-line bus services and purely on-demand systems, as they offer demand-responsive services within the framework of traditional scheduled bus transportation. Similarly to most transportation systems dedicated to serve several demands with the same vehicle, demand-adaptive transit systems involve a complex set of planning activities made up of many interrelated decisions. The main steps and goals of the planning activities are the same for traditional and demand-adaptive transit systems. Yet, the particularities of DAS services make for a different planning process and require the development of new methodologies. This differentiation also impacts the evaluation processes of DAS lines, either as stand-alone systems or as part of broader city-wide planning activities. The goal of this paper is to identify these differences, describe their impact on evaluation and planning processes, and provide a framework for the evaluation of DAS lines.
On the design of a flexible transportation system
NONATO, Maddalena
2009
Abstract
Important events, such as the foreseen Expo due in Milano in 2015, pose challenging logistic problems to the organization. The additional demand of transportation will often add on already congested situations that characterize most of our cities. At the same time, though, the duration of such events is limited in time, so that it does not justify consistent investments in building permanent infrastructures that would not be exploited beyond the terms of the specific event. Flexible transportation services can offer an alternative solution to such problems, since they require light infrastructure and can be easily reconverted once the event is over. Moreover, the demand is only partially foreseable so that any candidate system should be able to quickly adapt to the revealed demand without further planning. Several types of flexible transport systems exists, however there is not an assessed methodology for their planning and management. In this paper we refer to a previously studied demand adaptive system, namely DAS, and we propose a thorough approach that encompass the design of the lines and their operation, exploiting optimization techniques based on mathematical programming for solving the decision problem that arise at each step. Demand-adaptive transit systems (DAS) display features of both traditional fixed-line bus services and purely on-demand systems, as they offer demand-responsive services within the framework of traditional scheduled bus transportation. Similarly to most transportation systems dedicated to serve several demands with the same vehicle, demand-adaptive transit systems involve a complex set of planning activities made up of many interrelated decisions. The main steps and goals of the planning activities are the same for traditional and demand-adaptive transit systems. Yet, the particularities of DAS services make for a different planning process and require the development of new methodologies. This differentiation also impacts the evaluation processes of DAS lines, either as stand-alone systems or as part of broader city-wide planning activities. The goal of this paper is to identify these differences, describe their impact on evaluation and planning processes, and provide a framework for the evaluation of DAS lines.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
