Railway Signalling Systems Research Articles

Reliability and Inspection Modelling of Railway Signalling Systems

The railway is one of the most prominent models of transportation across the globe and it carries a large number of people, thus requiring high reliability, maintainability and safety. The reliability of railways mostly depends on an effective signalling system, making it one of the critical parts of railway operation. A signalling system is part of a large array of systems with interconnected components and subcomponents. Therefore, there is a need to make the signalling system more reliable and optimised with enhanced fault detection. Proper inspection and maintenance are required to make the signalling system reliable and safe. In this study, different inspection modelling techniques are applied to find the reliability of the signalling system. The signalling system has been divided into subsystems (signal unit, track unit, point-and-point machine) considering their importance and their effects on the failure rate of the entire signalling system. Inspection modelling of each subsystem has been conducted to provide the basis for the entire signalling system. A case study has been investigated to validate the model developed in one of the busiest tracks in eastern India. The obtained data thus are used to analyse the inspection pattern of signalling subsystems. Special attention to maintenance for inspection activities and logistics support has been taken into consideration, which is required to improve the reliability and maintainability of signalling subsystems and systems to make the railway signalling system sustainable in the long run.

From French National Signaling Systems to ERTMS: Considering the Evolution of Track-Side Systems

In France, the railway lines are divided into the national and international lines. While the former has a proper implementation of the railway signalling systems as relay-based or computer-based systems, the latter follows the guidelines defined by the ERTMS standards, focusing on the interoperability throughout Europe. In a previous work we presented how the national legacy relay-based Railway Interlocking Systems (RIS) can evolve to use a computer-based technology in order to benefit from its advantages. In this present article, we present how these computer-based systems can be used in order to allow the evolution from a national line towards an ERTMS compliant international line. This proposition is based on the fact that the previous work provides the support for evolving the track-side technologies with, for instance, the use of GNSS for the train geo-localisation instead of electrical circuits-based train detection systems. Then, a discussion of the impact of this evolution over the system safety is presented.

The Application of a Safety Comparator in the Track Circuit of a Railway Signaling System for Counting Overvoltage

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

<b>Lifetime Evaluation Method for Electronic Equipment of Wayside Signalling Systems</b>

It is often difficult to determine the intervals at which trackside electronic equipment for railway signalling system needs to be replaced. In a previous study, Fujita et al. proposed a lifetime evaluation method for electronic interlocking equipment installed in an indoor environment. In this paper, the authors focus on the electronic equipment used in wayside signalling systems, which is exposed to more severe outside conditions. We evaluated the lifetimes not only of electronic components but also of substrates. The results of a case study using the developed evaluation method are also reported. Lifetimes depend on operating environment stress factors, especially temperature changes. Therefore, we recommend that replacement intervals should be adjusted according to the operating environment.

Refined cost control and management methods for high-speed railway signal projects

The paper concentrates on a cost control and management problem of high-speed railway signal systems when the project managers require to organize, implement, and assess the project cost. When it comes to the existing issues of implementing railway signal project, the management process’s actual performances are presented, including the weak awareness of refined management and the lack of the financial management information system. Aiming to reduce project cost and safe operation of the signal systems, the refined cost control and management methods and concrete measures are presented during the concrete stage involving project bidding, preparatory, implementation, and completion.

Design of railway signaling system using IR sensor as train detection

In this research would try to give contribution for researchers or academics about simulation of the railway signaling system. The model of railway system was built using miniature of track and train model. Small LED was used as a lamp signal. Point machine was moved by servo motor controlled by Arduino Nano. The last, track circuit was replaced by proximity sensor using IR transceiver. The result showed that the simulation could do some basic task which is occurred in railway signaling system. The design of system was created by FSM (Finite State Machine) method which would be implemented in PLC (Programmable Logic Controller). It consists of state diagram, declaration of inputs and outputs, generated logic equation, and finally is the written code in ladder logic diagram. Set route test also has been tried successfully and the lamp signal showed the color aspect correctly.

Application of OFDM transmission method for railway signalling system via track circuit

At present, railway signalling systems in which control information is transmitted via track circuits (rails) have been deployed in many applications, such as automatic train control (ATC) systems in Japan. In these systems, it is difficult to increase the transmission speed due to the transmission characteristics of rails. To overcome this problem, we have proposed a new transmission method using orthogonal frequency division multiplexing (OFDM) and evaluated a configuration in which data judgment using majority decision was applied for improving the bit error rate (BER) characteristics. In this paper, we describe an FPGA implementation of our proposed method and the performance of the implemented devices.

Evaluation of an error correction function using correlation characteristics of spread codes in CDMA-based transmission methods

In previous researches, we have proposed novel modulation methods such as the CDMA-QAM method in which Code-Division Multiple Access (CDMA) and Quadrature Amplitude Modulation (QAM) are combined, and applied these methods for improvement of railway signalling systems. Although a rail is used as a transmission medium, there are severe conditions for transmission, such as strong attenuation at frequencies above about 10 kHz. To overcome this restriction, we attempted to improve the S/N characteristics in our proposed method. Specifically, we focused on correlation characteristics of spread codes which are used in CDMA. In this paper, we show that an error correction function that does not require additional bits for such correction can be realized by using the correlation characteristics. We evaluated the effectiveness of this correction method and conducted computer simulations in which the method was employed for CDMA-based transmission.

Improving Human Reliability Analysis for Railway Systems Using Fuzzy Logic

The International Union of Railway provides an annually safety report highlighting that human factor is one of the main causes of railway accidents every year. Consequently, the study of human reliability is fundamental, and it must be included within a complete reliability assessment for every railway-related system. However, currently RARA (Railway Action Reliability Assessment) is the only approach available in literature that considers human task specifically customized for railway applications. The main disadvantages of RARA are the impact of expert’s subjectivity and the difficulty of a numerical assessment for the model parameters in absence of an exhaustive error and accident database. This manuscript introduces an innovative fuzzy method for the assessment of human factor in safety-critical systems for railway applications to address the problems highlighted above. Fuzzy logic allows to simplify the assessment of the model parameters by means of linguistic variables more resemblant to human cognitive process. Moreover, it deals with uncertain and incomplete data much better than classical deterministic approach and it minimizes the subjectivity of the analyst evaluation. The output of the proposed algorithm is the result of a fuzzy interval arithmetic, $\alpha $ -cut theory and centroid defuzzification procedure. The proposed method has been applied to the human operations carried out on a railway signaling system. Four human tasks and two scenarios have been simulated to analyze the performance of the proposed algorithm. Finally, the results of the method are compared with the classical RARA procedure underline compliant results obtain with a simpler, less complex and more intuitive approach.

A Study on the Applicability of STAMP for Design Safety Assessment of Railway Signal System

A Study on the Applicability of STAMP for Design Safety Assessment of Railway Signal System

Relationship between Equipment Life and Component Life in Electronic Equipment for Railway Signalling Systems

Relationship between Equipment Life and Component Life in Electronic Equipment for Railway Signalling Systems

Application of a Non-carrier-Based Modulation for Current Harmonics Spectrum Control during Regenerative Braking of the Electric Vehicle

The regenerative braking of railway vehicles is widely used in DC railway systems all over the world. This mode of operation provides an opportunity to reuse part of the energy consumed by vehicles, and makes the railway system more energy efficient. During regenerative braking, not only energy management is an issue, but also Electromagnetic Compatibility EMC issues, such as interference of generated current harmonics with a railway signaling system. In this paper, the selective harmonic elimination modulation technique (SHE-PWM) was introduced to the traction drive with a three-level inverter to reduce specific catenary current harmonics generated during regenerative braking. The simulation model of a traction drive appropriate for harmonics analysis was proposed and verified by the measurements in the low-power laboratory drive system. The model was re-scaled to the 3 kV DC system for further study. The model of an induction motor with electromotive force and the method of its calculation was proposed. Furthermore, an analysis of the braking chopper operation was carried out. The asymmetric control of braking chopper was proposed to reduce the current harmonics below limits during chopper operation.

Optimization method of switch jumper setting based on strategies for reducing conductive interference in railway

Traction current can to impose conductive interference on the railway signalling system, which is also known as unbalanced traction current interference. In the station turnout section, the traction current may cause obvious interference on both receiving apparatus of track circuit and cab signalling apparatus due to the installation of multi-jumpers, wing rails, and insulated joints inside the turnout. This paper analyzes the above structural characteristics of turnouts in depth. By establishing a comprehensive simulation model of one-transmitter and two-receiver track circuit in turnout section and simulating the complete return current path along with traction network–locomotive–rails, the mechanism of traction current conductive interference in the turnout section is then illustrated, using Multisim and MATLAB/Simulink simulation platform. Finally, based on the Analytic Hierarchy Process (AHP), an optimization method of switch jumper setting is studied. The simulation results show that the conductive interference in the turnout section mainly involves two factors: The inherent turnout structure definitely results in different impedance of two rails, and the inductive cab signal is partly bypassed in the turnout center (nose rail). Especially, conductive interference magnitude depends on the jumper location. Therefore, in engineering practice, it is feasible to reduce the interference to a certain degree by reasonable settings of the switch jumper.

The CLEARSY safety platform: 5 years of research, development and deployment

• Smart combination of B formal method and diverse electronics. • Safety critical systems do not require high profiles anymore. • Connection with DSLs to seamlessly integrate existing development cycle. • Connection with proved system-level model, to derive software specification. The CLEARSY Safety Platform (CSSP) was designed to ease the development of safety critical systems and to reduce the overall costs (development, deployment, and certification) under the pressure of the worldwide market. A smart combination of hardware features (double processor) and formal method (B method and code generators) was used to produce a SIL4-ready platform where safety principles are built-in and cannot be altered by the developer. Summarizing a 5-year return of experience in the effective application in the railways, this article explains how this approach is a game-changer and tries to anticipate the future of this platform for safety critical systems. In particular, the education of future engineers and the seamless integration in existing engineering processes with the support of Domain Specific Languages are key topics for a successful deployment in other domains. DSL like Robosim to program mobile robots and relay circuits to design railway signaling systems are connected to the platform.

Towards safer rail control, command and signalling in the context of digitization

Aim . The state of the art of railway computer-based control, command and signalling (CCS) systems is characterized by high requirements in terms of dependability, functional safety and cybersecurity under the conditions when digital transformation and challenges associated with the demand for increased competitiveness of railway transportation force the transition to new paradigms in engineering, testing, verification, validation and standardisation to facilitate and speed up the process of development and implementation. It is expected that while preserving the level of dependability and safety, at least, as it is, the industry has to enable the maximum possible introduction of innovative solutions and digital tools aimed at further automation of CCS systems to enhance the capacity and throughput of railways and the performance of systems, to minimize the impact of the human factor and reduce the number of failures and downtimes. In this context, the key factors are the interoperability (technical and operational compatibility) of systems and the technological independence of railway operators and infrastructure managers from the designer/supplier of railway automation systems, eliminating the vendor lock-in effect. Methods . The paper gives an overview of the state of the art of railway computer-based control, command and signalling using the example of the EU and provides an analysis of these systems in terms of dependability and safety in the context of migration to new grades of automation. Results . The author has considered the evolution of control, command and signalling systems in the EU using the example of the European Railway Traffic Management System (ERTMS). The analysis covered the general trends and approaches to engineering, testing, verification, validation and standardisation of railway CCS systems. The paper has overviewed the major EU research and design programmes of CCS development with the dependability and safety methodology taken into account. A special attention has been given to the methods of open engineering, remote lab testing and standardisation of ERTMS interfaces. Conclusions . In the context of digital transformation, the development of state-of-the-art railway computer-based CCS systems implies an accelerated introduction of a whole range of innovative solutions and a wide application of commercial off-the-shelf components (COTS), thus making systems more complex and being capable of affecting the dependability parameters. In order to maintain these parameters at a specified level and to minimize the impact of human factors, the railway community is increasingly using formal methods and automated means of engineering, diagnostics and monitoring at all stages of the system’s lifecycle. A major factor of dependability is the standardisation of the system’s architecture, interfaces, open source design and testing software, including the standardisation of approaches to remote lab testing of products by different manufacturers to prove the reliability of operation at the boundaries of systems of various manufacturers.

An improved risk assessment method based on a comprehensive weighting algorithm in railway signaling safety analysis

There remains a lack of applied research on risk assessment technology in the safety analysis of the railway signaling system, and the research method in the existing literature mostly is the Analytic Hierarchy Process (AHP). This paper synthetically analyzes and evaluates the merits and demerits of the traditional AHP, the Maximum Absolute Weighted Residual (MAWR), and the Maximum Entropy Method (MEM), finally proposes a comprehensive weighting algorithm organically combining above methods. This algorithm applies to the weighting process under different evaluation matrix conditions. It neutralizes the excessive deviation caused by the human factors in the subjective weighting method and the data factors in the objective weighting method, so it makes the weighting result more reasonable. In addition, based on the comprehensive weighting algorithm, three kinds of typical railway signaling equipment are selected as calculation cases, and the weighting results can be applied in calculating the equipment dangerous failure rate, assessing the equipment safety level, and other risk management processes. This algorithm has practical application value for the risk assessment of the railway signaling system and its apparatus.

철도제어시스템을 위한 높은 신뢰성을 갖는 제어시스템 구조 연구

In the railway, signaling systems are located in the wayside and on-board as the very vital control system ensuring the safety operation of the train. Since a trivial failure of this signaling system can cause a fatal railway accident, the securement of high safety and availability of the signaling system is becoming a very important issue. In order to secure the high safety and availability of vital signaling system, efforts need to be made in many aspects of the hardware architecture, software and system lifecycle. Among of these, this paper focuses on the hardware architecture of railway signaling system. Currently, there are several hardware architectures applied to railway signaling systems, including the single, duplicated, and triple redundancy architectures. Single and duplicated redundancy architectures can cause fatal accidents because the whole system is affected when accident occur. For this reason, triple redundancy architecture has been the more popular for vital signaling systems. But this architecture has problems regarding its installation in the railway vehicle, as it occupies a large space and is intrinsically heavy in weight. We propose a noble fault-tolerant architecture for the vital railway signaling system that is triple redundancy-based, a cost-effective architecture that satisfies the installation conditions of space and weight.

The Impact of the High Voltage Power Lines Coupling on the Railway Signaling System

The Impact of the High Voltage Power Lines Coupling on the Railway Signaling System

Design and Implementation of a Control, Monitoring and Supervision System for Train Movement Based on Fixed Block Signaling System with AVR Microprocessor

Railway signaling and control systems are vital for the safe control of transport processes in rail traffic. Today, industry uses many processes, such as railway signaling systems, that must be controlled. Manufacturers of such systems have tried to update their products in line with modern industrial control technologies. In this paper, the possibility of using the common industrial automation equipment for a signaling system are investigated. Different parts of the signaling system, including wayside equipment, field element controls (interlocking and object controller) and supervision systems were specified. Then, the interlocking logic was extracted based on a fixed block signaling system. Control, monitoring and supervision systems were designed with an AVR microcontroller and then implemented on printed circuit board. Finally, the outputs of the system and its results with various railway lines, based on chosen layout, were analyzed and its applications identified. These applications include wayside equipment monitoring, the training of traffic control operators, and movement safety tests of the line before setup of the main system.

GNSS Fault Detection and Exclusion Based on Virtual Pseudorange‐Based Consistency Check Method

Although there have been many implementations of Global navigation satellite system (GNSS) in rail transport systems, the integrity assurance of GNSS positioning is still not highly concerned by the users. Integrity is a significant issue for specific safety-relevant GNSS railway applications, especially the railway signaling system which requires a critical safety level. Classical integrity monitoring solutions require an acceptable satellite visibility level to carry out Fault detection and exclusion (FDE), and this restriction leads to a degraded availability of FDE and final position computation. In order to break the limitation by satellite visibility, a consistency check method for FDE is proposed based on the virtual satellite pseudorange data, which is established based on the track database. Results from simulations show that the presented method can detect and exclude different types of faults effectively. Compared with classical residualbased GNSS integrity monitoring algorithm, the presented method achieves a higher FDE availability and makes better use of the satellite measurements even under the limited GNSS observing conditions.