Improving Human Reliability Analysis for Railway Systems Using Fuzzy Logic

The human factors area is one of the core field of industrial safety. It is deeply recognized that human factors are the main cause of accidents and breakdowns in various industries. Physiological mental states of human operators, like fatigue or vigilance, are crucial for the evaluation of human operators reliability. However, the shortages of measurements of physiological mental states limit their application. So human reliability analysis (HRA) is developed and many techniques have been developed. Among these techniques, cognitive reliability and error analysis method (CREAM) is often applied and discussed. Due to the application limits of common performance conditions (CPCs) in original CREAM approach, it is advised to generate a new list of CPCs for the application domain if CREAM approach is applied to other domains. In this contribution, a new approach defining a situated and dynamical human reliability measure is established. The approach is based on the well-known CREAM approach, which is modified with respect to the use in dynamical context. The new list of CPCs, their levels and corresponding effects on human reliability are determined. A new index, human performance reliability score (HPRS), is proposed for the assessment of human operator reliability. Finally, the applicability and correctness of the newly established approach is verified by data analysis.

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.

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.

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.

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.

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 study of human reliability has traditionally taken an ``error-rate'' approach, with the emphasis on identifying and reporting supposedly consistent and basic error-rate levels for various manual activities. This paper approaches the study of human reliability by identifying numerous factors that tend to increase the probability that errors will occur in computer-based business information systems. The major causal factor categories are personal, design, documentation, training, source data, man-machine interface, and environment. This causal factor approach suggests that most human-generated errors can be prevented by eliminating the factors that cause errors to occur.

The traditional approach to the study of human factors in the maritime field involves the analysis of accidents without considering human factors reliability analysis. The main approach being use to analyze human errors are statistical approach and probability theory approach. Another suitable approach to the study of human factors in the maritime industry is the quasi-experimental field study where variations in performance (for example attention) can be observed as a function of natural variations in performance shaping factors. This paper analyzes result of modeling human error and human reliability emanating from the use of technology on board ship navigation in coastal water area by using qualitative and quantitative tools. Accident reports from marine department are used as empirical material for quantitative analysis. The literature on safety is based on common themes of accidents, the influence of human error resulting from technology usage design, accident report from MAIB and interventions information are use for qualitative assessment. Human reliability assessment involves analysis of accident in waterways, emanating from human-technology factors interface. This paper report an enhancement requirement of the methodological issues with previous research study, monitoring and deduce recommendations for technology modification of the human factors necessary to improve maritime safety performance. The result presented can contribute to rule making, and safety management leading for development of guideline and standards for human reliability risk management for ship navigating within inland and coastal waters.

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.

Despite significant progress in the development of microelectronic rail automatic systems observed in recent decades, relay-contact devices are still widely used in railway signalling systems, that are fundamental to the safe operation of railways and must perform predictably and reliably.Thus, signalling relays used for safety-critical or safety-related applications in railway signalling systems should be properly maintained and tested to ensure their performing safely and reliably throughout their expected service life.With the purpose of developing a method for detecting defects in movable armature of the signalling relay, the time dependences of transient currents during relays switching have been investigated for relay in various technical conditions: in operable condition, as well as with artificially created defects (bends) of contact springs. The measured data have been analyzed in the time and frequency domain using the wavelet transform modifications (CWT, DWT, DWPT).The analysis of the transient currents was carried out using segmentation of the current characteristics of the relay. The relay transient current at first and third segments which corresponded to unmovable anchor state, increase with time during relay switch-on approximately as the exponential function.The time constants of the relay current were calculated by approximating the measured current-time dependences at the first segment of the current curve by exponential function.The presence of defects in the movable armature of the relay had practically no effect on the values of calculated time constants.However, these values strongly depended on the technical condition of the relay magnetic circuit and the relay coil, as well as on the voltage applied to the coil terminals. This behavior of the relay time constant on the first segment of the relay current characteristic makes it possible to use this parameter to monitor the technical state of the electromagnetic relay system.Defects of the armature and contact springs led to the appearance of additional features at the second segment of the relay transient current, which corresponded to the movement of the armature. The magnitude of these features on the current curve depended on the value of bending of the relay's contact spring. The width and appearance time of the features at the second segment of the current-switching curve correspond to the non-simultaneous switching of the relay contacts. To determine the amplitude (energy) of these features (peaks) on transient current curve, their duration and the times of appearance, the wavelet transform was used. The results of investigations confirmed the possibility of determining the defects of the relay movable armature by using wavelet analysis of the second segment of the relay transient current characteristic.

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.

Accident databases commonly contain factual information about the time and date of each accident, vehicle characteristics, number of persons killed and injured, and other kinds of factual data. These attributes of the environment and equipment are usually directly represented in databases. In contrast, detailed analysis of accident causes, including human factors information, are frequently not represented because they are much more difficult to obtain and code. This paper explores the suitability of transportation accident databases for use in human factors research. Given the goal of reducing the number and severity of transportation accidents, it is useful to use accident data as a tool to understand the common causes of accidents. Problems arise, however, because existing databases were typically not created explicitly for research purposes, and coding systems and file structures often omit or obscure useful information. Improved coding schemes and file structures that promote the use of databases for human factors research are discussed. Accident investigation methodologies that can improve the quality of human factors information in databases are also considered. Finally, problems associated with the use of existing databases are noted.

This tutorial E-book is based on the long-standing experience of teaching railway operations and signalling at TU Braunschweig and other universities and higher vocational training institutions in different parts of the world. It explains the fundamental principles all railway signalling systems have in common. This is done in a generic way that does not focus on specific national solutions. It covers basic elements and terms, principles for safe train separation, interlocking principles, automatic train protection, and level crossing protection. It also contains a glossary with definitions of relevant terms.

The main objective of the study is to establish a correlation between the main causes of road traffic accidents in Romania and “human factors”. The aim of the study is to show that accidents are attributed exclusively to human mistakes in a higher percentage than. The data used in the research are taken from the database of the Traffic Police-for Road traffic accidents during 2013-2022 and from the database of the Romanian Road Authority - ARR - for road safety inspections during 2018-2021. From the perspective of human factors, the research will give answers on the nature of the causes that lead to the production / favouring of road accidents in Romania and will propose solutions to address road risks to improve road infrastructure safety. As a case study, the research will focus on the human factors that contribute to road accidents on National Road 2. Compared to other national roads, on DN 2 road accidents occur with the highest number of fatalities, approximately 8.28% of all road deaths nationwide. The analysis of findings from road safety inspection reports carried out on DN2 shows that there is a correlation between road infrastructure non-conformities and causes of road traffic accidents.

A bibliometric analysis of human reliability research