Formalising the Hybrid ERTMS Level 3 specification in iUML-B and Event-B

Abstract

We demonstrate refinement-based formal development of the hybrid, 'fixed virtual block' approach to train movement control for the emerging European Rail Traffic Management System (ERTMS) level 3. Our approach uses iUML-B diagrams as a front end to the Event-B modelling language. We use abstraction to verify the principle of movement authority before gradually developing the details of the Virtual Block Detector component in subsequent refinements, thus verifying that it preserves the safety properties. We animate the refined models to demonstrate their validity using the scenarios from the Hybrid ERTMS Level 3 (HLIII) specification. We reflect on our team-based approach to finding useful modelling abstractions and demonstrate a systematic modelling method based on the state and class diagrams of iUML-B. The component and control flow architectures of the application, its environment and interacting systems emerge through the layered refinement process. The runtime semantics of the specification's state-machine behaviour are modelled in the final refinements. We discuss how the model could be used to generate an implementation using code generation tools and techniques. Abbreviations ADT Abstract Data Type RodinRodin platform ERS

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].…”

Introduction to special section on the ABZ 2018 case study: Hybrid ERTMS/ETCS Level 3

“…The article Formalising the Hybrid ERTMS Level 3 specification in iUML-B and Event-B, by Dghaym et al [6], describes the use of UML-B for modelling and analysis of the ERTMS case study. UML-B is a graphical version of Event-B that provides class diagrams and state machine diagrams based on UML.…”