Analysing an autonomous tramway positioning system with the Uppaal Statistical Model Checker

Abstract

The substitution of traditional occupancy detecting sensors with an Autonomous Positioning System (APS) is a promising solution to contain costs and improve performance of current tramway signalling systems. APS is an onboard system using satellite positioning and other inertial platforms to autonomously estimate the position of the tram with the needed levels of uncertainty and protection. However, autonomous positioning introduces, even in absence of faults, a quantitative uncertainty with respect to traditional sensors. This paper investigates this issue in the context of an industrial project: a model of the envisaged solution is proposed, and it is analysed using Uppaal Statistical Model Checker. A novel model-driven hazard analysis approach to the exploration of emerging hazards is proposed. The analysis emphasises how the virtualisation of legacy track circuits and on-board satellite positioning equipment may give rise to new hazards, not present in the traditional system.

Implementation of a Model-Oriented Approach for Supporting Safe Integration of GNSS-Based Virtual Balises in ERTMS/ETCS Level 3

“…In [47]- [49], the authors investigate specific MB scenarios by considering the ETCS On-board interface with the train localization unit, while abstracting away the specific localization functionalities coming from balises or GNSS. In [50], the occupancy of virtual tramway track sections at a simple junction was modeled and analyzed, considering random intervals around tram location continuously provided by means of a GNSSbased system. However, to the best of our knowledge, no study has provided comprehensive formal models that allow for quantitative assessment of safety properties pertaining to the use of GNSS-based localization systems in the railway domain, in particular with the operating principles specific to Virtual Balises.…”

Safe and Secure Future AI-Driven Railway Technologies: Challenges for Formal Methods in Railway

“…An example is the Hybrid ERTMS/ETCS Level 3 concept, which tries to bring the flexibility of moving block train separation to a signalling system based on traditional trackside train detection [58]. The application of formal modelling and analysis techniques have proved to be beneficial for improving the specification of the concept and for coping with its complexity [10,31,7,38,41,62,81,57,15].…”

“…It also developed, tested, and validated a CSIRT model and prototype co-designed with the relevant rail stakeholders. Notable new projects on intelligent systems are IN2SMART2 15 , which is concerned with smart maintenance of Railway assets, SMART2 16 , which aims at an integrated automated system for obstacle and track intrusion detection, and PERFORMINGRAIL (PERformance-based Formal modelling and Optimal tRaffic Management for movING-block RAILway signalling) 17 .…”

Future Train Control Systems: Challenges for Dependability Assessment

“…In [5], the authors investigate this issue with the definition of a model of the envisaged solution, and its analysis using UPPAAL Statistical Model Checker. The analysis emphasises how the virtualisation of legacy track circuits and onboard satellite positioning equipment may give rise to new hazards, not present in the traditional system.…”