Gabriele Malavasi

Simulation of stochastic elements in railway systems using self-learning processes

Abstract The railway traffic follows deterministic rules, whose selection and application depend on the choices of human operators. These choices may be different in similar situations and produce different effects on the circulation. The difficulty to code, in a general and comprehensive way, these behaviours suggested to test the use of systems capable to reproduce events without requiring a previous definition of the operating rules but acting by means of self-learning processes. The present research deals with: • an analysis of the critical behavioural parameters, difficult to be effectively modelled by means of analytical simulation tools; • the selection of the self-learning process for the application to the reliability of a railway network capable to work as a part of a wider simulation model of railway traffic; • the development of a preliminary version of the model simulating the stochastic failure events and its application to a case study.

A synthetic approach to the evaluation of the carrying capacity of complex railway nodes

The evaluation of carrying capacity of complex railway nodes is a typical problem to be faced in metropolitan areas. This paper initially analyzes a few methods (Potthoff methodology, Probabilistic approach and Deutsche Bahn procedure) for the evaluation of carrying capacity of complex railway nodes. The aim of the article is to investigate commonalities and differences among these methods in order to try (even in the continuation of the research) to identify potential margins of improvement or to formulate a new approach to evaluate the use of stations in a synthetic mode, considering the characteristics and the limits of the existing and analyzed models. The results of the theoretical analysis have been validated by means of applications to typical case studies.

Capacity Analysis Of Suburban Rail Networks

As is well known, capacity evaluation and the identification of bottlenecks on rail networks are complex issues depending upon several technical elements. This is even more perceptible in metropolitan areas where different services (freight, long distance, metro/regional, etc.) are operated using the same limited infrastructures; as a consequence, these facilities may represent bottlenecks of the rail system since they are often highly utilized and congested. This paper tries to explore the issue of capacity evaluation of complex rail networks, proposing synthetic indicators and analyses for feasibility studies or strategic planning. The presented methodology suggests taking into account the main differences in infrastructure characteristics (e.g. single or double lines, signalling systems, terminus or passing stations, etc.) and rail services (e.g. diverse rolling stock, various frequencies, average distances and number of stops, etc.) in order to propose a general approach applicable for capacity analysis of a network as a whole, hence evaluating the utilization rate and the congestion on both lines and stations. To better explore and validate the methodology, an application to a line of the Naples’ suburban network is presented. The results confirm the applicability and effectiveness of the proposed approach; the outcomes indicate the capacity utilization rate of the considered facilities, pointing out likely bottlenecks and possible actions to improve the system efficiency.

RAILWAY TRAFFIC SIMULATION BY MEANS OF A PETRI NET MODEL

This paper explains the primary results of ongoing research concerning the development of a network model, including lines and stations, capable of simulating traffic operations on the basis of the actions performed by the signaling components; this approach allows a high flexibility and capability to manage the traffic command and control operation. The model feasibility has been demonstrated and a global network model has been built up. The represented network may be analyzed with the simulation of different timetables without traffic density constraints. The main outputs of the model application are: 1) the global rate of occupation for line and station components; and 2) the traffic development representation with the underlying of the critical situation. The model was successfully tested on a network including a line section equipped with a codified currents automatic block signaling system and 2 stations.

Rail Education in Italy: The Successful Experience of Cooperation Between Academia and Industry at Sapienza

The aim of this paper is to describe three different examples of cooperation between academia and industry in the field of railway transport that have been successfully carried out at the University of Rome “La Sapienza” in the last few years. The first experience is the postgraduate course in “Railway Infrastructure and Systems Engineering” promoted by “La Sapienza” and funded by the major rail companies operating in Italy that for years represents perhaps the most important initiative in Italy to train and then hire young engineers in the rail sector. The second experience is a course on “Risk assessment in the Railway Sector” delivered by “La Sapienza” for engineers employed in Trenitalia, the main Italian Railway Undertaking, owned by FS Italiane Group. This type of training is more common, but it is interesting to note that companies in Italy require academia to train their engineers in a crucial and rapidly evolving field such as railway safety. The last experience is a specialization course in “Infrastructures and Railways System” designed and delivered together by “La Sapienza” and Italferr, the engineering service company of the FS Italiane Group, for the Sultanate of Oman Ministry of Transport & Communications, which is an interesting example of how companies and academia can work together to export Italian railway know-how to the world. It is possible to note that the three cases are examples of three different levels of collaboration between academia and companies: the first level concerns the recruitment and the basic training of young engineers to be employed in companies; the second the specialist training of engineers already employed in companies; the third a training activity for third parties useful to export Italian railway know-how and technology in the world.

Road accessibility model to the rail network in emergency conditions

Abstract This research project considers a quantitative model for analysing the accessibility of open-air stretches of a railway line in emergency conditions using the road system (Borghetti, 2014). The project derives from a previous study (Borghetti and Malavasi, 2016) which illustrated the problems regarding the vulnerability of a railway stretch with particular reference to accessibility in emergency conditions; a method for evaluating accessibility was proposed, with reference to a specific territorial situation. This work will examine in detail the analytic structure of the individual indicators that make up the model. An Accessibility Index was determined for each railway link i of homogeneous length, starting from an evaluation of the territorial and contextual characteristics in which the line is positioned. The analysis procedure consists firstly of identifying those parameters that compete in implementation of the Accessibility Index, and secondly in aggregating the Indicator parameters which, through the use of relatively important weights, are part of Index determination. The model is based on a comparative approach that places the Accessibility Index in relation to the links that make up a railway stretch, therefore identifying the priorities and a hierarchy of the management and/or infrastructural interventions carried out to improve accessibility should important events occur.