Performability Analysis of a Tramway System with Virtual Tags and Local Positioning

Abstract

Current solutions for tramway Interlocking Systems are based on physical sensors (balizes) distributed along the infrastructure which detect passing of the trams and trigger different actions. This approach is not easily scalable and maintainable, and it is costly. The Regional Project SISTER aims at designing new architectural solutions for addressing the previous problems based on the virtualization of the sensors and on the local positioning of each tram. The idea is to trigger actions when the computed local position corresponds to a virtual tag. However, the computed position can be affected by errors, compared to the real one. Therefore, it is important to understand the impact of these new solutions on the performability of the system. This paper focuses on the analysis of the performability of a tramway system, based on the SISTER architectural solutions. We build a model using Stochastic Activity Networks and run sensitivity analyses on i) the accuracy of the positioning, ii) the different SISTER parameters (e.g., those triggering the activation of manual procedures). This analysis allows us to properly set and fine-tune the key architectural parameters, to understand the impact of the accuracy on the positioning, and to understand the impact of failures.

Stochastic Activity Networks Templates: Supporting Variability in Performability Models

“…We base our work on SANs because of their wide adoption across different domains, thanks to their flexibility and the support provided by the Möbius tool [14]. For example, recent work has employed models based on SANs to evaluate control strategies of smart grids [15], the availability of a backbone network [16], the performance of scheduling algorithms [17], performability in the railway domain [18], and the quality of experience of a distributed interactive application [19].…”

A stochastic modeling approach for traffic analysis of a tramway system with virtual tags and local positioning

“…None of the previous works is considering the distinguishing aspects of the SISTER solutions based on the virtualization of the physical sensors. This paper builds on [4], which introduced the stochastic modeling approach for the quantitative analysis of the SISTER system, and presented the analysis of a simple tramway scenario with one line and one route only. The key extension provided in this paper is the possibility to define and analyze more complex and realistic tramways networks, with several routes and with intersections of lines.…”

“…This paper is an extended version of [4], where we introduced the basic elements of the modeling approach targeting a quite simple scenario with one single route and one single track only. In this work, we provide the following key extensions:…”