Railway Signalling Principles

In accordance with the development of recent computer technology, the dependency of railway signaling system on the computer software is being increased further, and accordingly, the testing for the safety and reliability of railway signaling system software became more important. This thesis suggested an automated testing tool for coding rules on this railway signaling system software, and presented its result of implementation. The testing items in the implemented tool had referred to the international standards in relation to the software for railway system and MISRA-C standards. This automated testing tool for railway signaling system can be utilized at the assessment stage for railway signaling system software also, and it is anticipated that it can be utilized usefully at the software development stage also.

Efficient and safe railway signalling systems, together with energy-saving infrastructures, are among the main pillars to guarantee sustainable transportation. ERTMS L3 moving block is one of the next generation railway signalling systems currently under trial deployment, with the promise of increased capacity on railway tracks, reduced costs and improved reliability. We report an experience in modelling a satellite-based ERTMS L3 moving block signalling system from the railway industry with Simulink and Uppaal and analysing the Uppaal model with Uppaal SMC. The lessons learned range from demonstrating the feasibility of applying Uppaal SMC in a moving block railway context, to the offered possibility of fine tuning communication parameters in satellite-based ERTMS L3 moving block railway signalling system models that are fundamental for the reliability of their operational behaviour.

This paper has been produced as part of the course material for the Railway Signalling and Control Systems Professional Development Course provided by the Institution of Engineering and Technology in June 2010. The paper provides an overview of the basic principles of train protection and cab signalling for mainline railways and explains how these principles have been applied to the ERTMS/ETCS train control system.

This paper describes how railway signaling systems are computerized equipment that are vital for the guarantee of the safe running of trains. Because of the computerization of railway signaling systems, the importance of a networking interface between these pieces of equipment is increasing. Thus, it is important to have a reliable and safe communication link between signaling equipment. Recently, network technologies have been applied in a real-time industrial control system, and also there are several studies applying computer network technology in vital control systems such as railway signaling systems. To deploy these computer network related studies in railway signaling systems, implementation costs, transmitted reliability, safety assurance technique and compatibility etc, are considered. The computer network protocol for railway signaling systems has an important advantage over the widely used Ethernet in terms of deterministic characteristics. This paper proposes computer network technology, especially the Ethernet, for railway signaling systems. The computer network characteristics of real-time industrial control systems and vital railway signaling systems are presented in this paper. This algorithm presented is based on switched Ethernet technology with a redundancy scheme. Also the paper demonstrates the experimental results of the proposed network algorithm.

Formalizing a subset of ERTMS/ETCS specifications for verification purposes

The railway signalling domain is a complex critical infrastructure, linking communication and number of control elements. Ensuring safety in railway signalling system is always considered as a guarantee of intact operation of the railway. Current signalling system composes of centralized controllers which provide a single feature such as interlocking, and level crossing control. The Indian Railways (IR) uses Panel Interlocking (PI), Route Relay Interlocking (RRI), and Solid State Interlocking (SSI) or Electronic Interlocking (EI) for signalling safety, however, permitting movement of the trains lies in the hands of a human. The main challenge is to combine multiple sources of data and define a system which can intensify the functionality of the system. This paper mainly focuses on development of an automated model, beneficial to Intelligent Signalling System (ISS). Assessing its ability to take a decision which authorizes the movement of trains according to the timetable and modify it depending on real-time information using Machine Learning (ML). For modelling, IR standard single line station layout is considered and graphical model-based design techniques are implied. For analysis consider the track sections as nodes, signals as the start point and the end point linked to specific routes and assessing the developed model for various operating scenarios keeping a strict check on completeness and consistency. Implementation of such system in the railway network will not only provide a comprehensive level of safety in railway transportation but also takes a step forward towards systematizing various methods and strategies such as rescheduling system, monitoring performance under one roof using ML

A new fail-safe node using transputers for application in railway signaling systems is reported. This fail-safe node provides fault tolerance and safe reaction, which are required for railway signaling systems. The basic scheme of the fail-safe node is discussed, together with the concepts of leadership based on rotation, recovery in the fail-safe node, reconfiguration, and safe shutdown. >

The railway signaling system is being converted to the computer system from the exiting electrical equipment, and then the dependency on software is being increased. So far, the software validation has been mainly dependent profess, the these methodology is just depended to software experts as a tester. So it is our situation where not only validation of the document on safety activities being required, but also another automatci testing tool for vital railway signaling software. There were difficult to take advantage at the existing software black-box testing tool like usage of internal memory access of target system. This paper have proposed a new black-box testing tools with enhanced usability and the represents the design and prototype result for proposed tool.

The simulation of a modern railway system on the cyber range will investigate the supple behavior of cyber-attacks in a modern digital railway system. The contemporary digital railway simulation architecture will focus on the railway's signaling system and the control command system, which is a classic SCADA system. With the introduction of IoT technology to railway systems, they have become vulnerable to cyber-attacks. The simulation is conducted on the cyber range server by simulating STCS. The cyber threats will be analyzed through penetration testing using Kali Linux on the simulated STCS on the cyber range. We analyze the impact of the threat agent groups, especially denial of service (DoS) and quay chain attacks that mainly target the STCS. The DoS attack generates the congestion of packets in the railway system network and will compromise the SCADA components in the STCS. The quay chain attack compromises the SCADA component, resulting in a delay in the signal system of STCS. The attack tree analysis helps us to understand the behavior of threat agents on STCS. Based on the research, we identified some mitigation techniques to reduce the cyber-attacks impact on the modern digital railway system.

A description is presented of an expert system called ADES (ATP design expert system) for the design of automatic train-protection (ATP) systems. (An ATP system is a railway signaling system consisting of a set of logic circuits that control the safe movements of trains within a railway station.) Artificial intelligence techniques proved feasible to address this particular design problem, and ADES, which uses artificial intelligence techniques, makes it possible to design good control circuits to meet operational requirements rapidly by using well-structured, explicitly represented knowledge on ATP. ADES' inference engine works as a partial evaluator for the knowledge representation language KARL which is used to write design rules. Since every circuit produced by the expert system is still expressed in KARL, the KARL interpreter has also been used as a simulator for a designed circuit. Prototypes of the inference engine and the KARL interpreter have been implemented as extended Prolog metainterpreters. >

Communication based Train Control(CBTC) system, the latest train control technology, has been widely applied throughout the world, because it has a number of advantages such as improved driving headway, reduction of the maintenance cost and so on. The technical core of CBTC is to ensure the safe space between trains through the real-time train tracking. Korean Radio-based Train Control System(KRTCS) has been developed as a Korean CBTC standard since 2010. KRTCS is comprised of Automatic Train Supervision(ATS), wayside/onboard Automatic Train Protection(ATP), onboard Automatic Train Operation(ATO), Electronic Interlocking(EI) and wayside equipment such as transponder tags, precision stop maker, communication network, etc. In the paper, we present system configuration of KRTCS and design and development scheme of Automatic Train Protection(ATP) communication interface for KRTCS. Communication between each component is performed using the protocol defined in the form of variable messages. Messages are divided into periodic or non-periodic messages. This study describes onboard and wayside ATP functional design and communication message and procedure for each function.

Recently, vital devices of the railway signaling systems have been computerized in order to ensure safe train operation. Due to this computerization, we have gradually come to need networking interfaces between these devices. Thus it is important that there be reliable communication links in the signaling systems. Network technologies are applied in the real-time industrial control system, and there are numerous studies to be carried out on the computer network technology for vital control systems such as railway signaling systems. For deploying the studies, we consider costs, reliability, safety assurance technique, compatibility, and etc. In this paper, we propose the Ethernet for railway signaling systems and also precisely describe the computer network characteristics of vital railway signaling systems. Then we demonstrate the experimental results of the proposed network algorithm, which is based on switched Ethernet technology with redundancy scheme.

The development of the effective and economical protection measures is vital for the railway signaling systems because the lightning damages cause the disruption of the railway transportation systems. In general, the railway signaling systems are set up at a wayside and directly connected to the rails through cables. The lightning surges can invade the railway signaling systems via the cables and cause damages to the systems. Accordingly, clarifying the propagation characteristics of lightning surges along the rails is essential to develop the lightning protection measures in the railway signaling systems. We have carried out the field tests to examine both surge impedance and surge propagation velocity of the rails. This paper proposes a calculation model of the surge propagation characteristics along the rails. We measured the frequency‐dependent four‐terminal parameters of the rails to estimate the distributed parameter adopted in the calculation model. The results of surge impedance and surge propagation velocity calculated by the proposed model almost agree with the experimental results. Moreover, the proposed model can calculate the surge attenuation along the rails. This model is applicable to the development of lightning protection measures for the railway signaling systems. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The next few years will see distributed real-time computer systems playing an important role in control systems of high-dependability applications, such as rail transportation. In these applications a failure in the temporal domain can be as critical as a failure in the value domain. In rail transportation, train control system has become more complex and the methods to ensure its correctness of have been considered outmoded. The safety of train control system is becoming increasingly important as computers pervade them on which human life depends and the failure to meet time deadline can have serious or even fatal consequences. This paper proposes a formal modeling and verification approach for real-time system. In the proposed method the real-time system is modeled by timed automata network (TAN) and verified by model checking which explores the state space to determine whether the system satisfies a given specification. The case study of ATP (automatic train protection) shows how the method can assist in designing more efficient and reliable real-time systems. Firstly, automatic train protection (ATP) system and timed automata network (TAN) model is proposed; secondly, the state transitions and multi-tasks ATP onboard model was modeled with TAN model, and then the time sequences of each task are expressed in UML sequence diagrams. Finally, the timing characteristics was verified to meet the requirement by UPPAAL model checker. A major conclusion of the survey is that formal methods, while still immature in some respects, can be used successfully to model and verify real-time systems.

Optimization of Railway Section Signalling Layout Based on Quasi-Moving Block