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SAtellite-based Signalling and Automation SysTems on Railways along with Formal Method and Moving Block validation

Periodic Reporting for period 2 - ASTRail (SAtellite-based Signalling and Automation SysTems on Railways along with Formal Method and Moving Block validation)

Période du rapport: 2018-09-01 au 2019-10-31

The innovation process of the railway transport is slow compared with the pace at which new technological advances become available today: other transport sectors are rapidly evolving thanks to the application of innovative solutions. This difference is ascribed to the robust safety that is strictly required by the railways.

The railway control and signalling system is expected to take advantage from the introduction of new technological solutions. For example, GNSS system could be used to implement an absolute positioning system on trains, allowing the adoption of a moving block system that can permit a better utilization of the line. Moreover, the introduction of automatic operations in the rail sector can increase performance of the train operation reducing delays and providing efficient energy management, while maintaining or even improving the safety level of the train operations.

The ASTRail project focused on the enhancement of the signalling and automation system by leveraging cutting-edge technologies from different sectors, such as the avionics or the automotive ones. Investigation of such technologies and assessment of their re-usability in the railway field were done taking in particular care all the issues related to safety and performance in the rail system.
In details, the research activities of the ASTRail project were organized into the following four Work Streams (WS):
- WS1: GNSS technology into the ERTMS Signalling System;
- WS2: Hazard Analysis of the railway system;
- WS3: Automatic driving technologies for Automatic Train Operations;
- WS4: Formal languages and methods to be applied in the railway field.

The conclusions of the ASTRail project action are summarized per Work Stream in the following:
- WS1: it addressed the study of different aspects related to the absolute positioning for railways: in particular, ASTRail investigated novel navigation architectures for positioning and drew some conclusions on an informed setting of Minimum Performance Requirements for it;
- WS2: ASTRail safety experts performed the Hazard Analysis of a Moving Block Signalling (MBS) System for all railway profiles;
- WS3: the ASTRail project investigated autonomous driving technologies in automotive and other application fields and it assessed their applicability in the railways;
- WS4: ASTRail project selected formal methods suitable for the railway domain and challenged them with the validation of the addressed new MBS.
Main results achieved by ASTRail by work-stream:

1) GNSS technology into the ERTMS Signalling System
The aviation standards and requirements were analysed with respect to their suitability for the rail domain. Various assumptions and requirements were identified for their applicability to the rail domain.
A GNSS-centric architecture for rails was defined considering previous works on the topic. Modelling of the local environment in terms of multi-path errors and radio interference was completed. A radio interference detection and mitigation algorithm was designed. Use cases and relevant position technologies complementary to GNSS were identified, as well as the most suitable approach for the GNSS integration with such complementary technologies. Work was undertaken on the design and testing of algorithms used to diagnose and detect GNSS faults from payload down to local failures. An informed setting of Minimum Performance Requirements (MPR) for the hardware and software was proposed

2) Hazard Analysis of the railway system
A model of the Moving Block Signalling (MBS) system was elaborated and some significant use cases were defined.
The main result was the Hazard Analysis of the MBS system that was concluded applying inductive techniques for Preliminary Hazard Analysis taking into account the defined system use cases and assuming that the main positioning system used will be based on GNSS.
The Hazard Analysis was supported by the MBS system model created with UML state charts and led to the definition of Safety Requirements for all determined hazards and the Safety Related Application Conditions in the area of Operation and Maintenance, where applicable.

3) Automatic driving technologies for ATO
A survey on the state-of-art of autonomous driving technologies was performed to select most promising mature and cutting-edge technologies from the automotive and other application fields. Implementation characteristics and operation conditions of the automotive and of the railway sector were compared to identify commonalities. This permitted to select the most promising technologies for future ATO. Lastly, a qualitative evaluation of the selected reusable technologies was performed considering specific ATO scenarios.

4) Formal languages and methods to be applied in the railway field
The analysis of the state-of-the-art and state-of-the-practice of formal/semi-formal methods in railways was performed. Criteria for ranking the formal languages and tools were first defined and, according to them, a ranking matrix has been conceived for a proper selection of formal methods and tools. Further activity consisted into the definition of a formal process and its application in the integration of the Moving-block system with Automated Driving Technologies The main output was an integrated specification of the system with a semi-formal model, together with its formal translation and formal verification.

Dissemination: ASTRail results were presented by several scientific papers, two newsletters, a brochure, a Mid-term and a Final ASTRail events.
For the exploitation ASTRail counted on IP2SC, X2RAIL-1/-2 and an Advisory Board which the activities were regularly reported to.
The ASTRail project targeted the enhancement of the signalling and automation systems in the railway sector. This enhancement may permit to increase the line capacity as well as the operation reliability, while maintaining the highest level of safety. Furthermore, the innovation brought by the ASTRail project can be exploited to reduce the costs of the railway sector.
A peculiar characteristic of ASTRail consisted in the investigation of the possible employment of technologies already adopted in other transportation sectors. This characteristic may permit also to speed up the time to market and to reduce the innovation cycle times of the railway sector.

The impacts of the ASTRail project are strictly related to each Work Stream:
- WS1: GNSS was studied in the railways with an approach borrowed from the aviation: the MPR identified by ASTRail represent a first milestone for the introduction of GNSS in the sector; also, the algorithms designed are likely to impact on different domains;
- WS2: Hazard Analysis can be exploited in following studies regarding moving block system safety integrity level in different railway applications (use cases) and also lay foundations for future certification activities of generic and specific applications of moving block;
- WS3: outcomes of the analysis on the technologies for automated driving can impact on the evolution of ATO, speeding up the adoption of new technological solutions;
- WS4: ASTRail results on the selection of formal techniques can hopefully facilitate a common knowledge and the exchange of information and tools across the sector.
Objectives and topics