Using Simulation to Assess Infrastructure Performance in Multicriteria Evaluation of Railway Projects

Economic evaluation of projects of new railway infrastructures is a typical step of feasibility studies, but it is rather common to take into account other than transport aspects of projects such as their environmental or land use outcomes. Multicriteria methodologies may support decision makers during the process of evaluation and choice of candidate projects; notwithstanding a large part of the applications in the railway sector carry out a careful analysis of the negative impacts of the alternatives, but the reasons for the actual realization of the project are neglected. In fact, a railway infrastructure project aims to improve an existing situation by means of expected positive effects on, for example, accessibility or travel times. Nonetheless, the economic revenues, the positive effects on the social sphere or the specific transportation–related matters that a project might generate are often left in the background. The authors propose a model that includes different attributes that can characterize a railway infrastructure, e.g. the flexibility rate, the comfort offered to travellers, the access times to stations, the vehicle maintenance savings, the served population, the ticketing revenues. Thus the aim of this paper is to introduce a new structure for the decision problem that includes criteria related to the positive outcomes of each alternative project as well as its negative effects. It is worth noting that positive outcomes are, to a great extent, measurable directly or they can be assessed by means of simulation models. Some of the transport–related criteria are indeed related to the inputs and outputs of stochastic simulation, which can reproduce most processes involved in rail traffic, including deterministic aspects and human factors. This is particularly relevant in order to simulate traffic under realistic conditions, considering variability at border, various driving styles and stop times..