• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.383-386
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• 2006

The safety of the railway system is important because the system is a mass transit system and the results of the accident are inconceivable. The railway system is operated by train operation system such as train control system. So the train control system requires safety critical characteristics. In the European railway, ETCS (European Train Control System) project has been finished to accomplish the interoperability of each national railway signaling system. According to the interoperability degree, ETCS levels are suggested. As the highest level, ETCS level 3 suggests a radio communication. Also recently urban railway system is operated by driverless and automatic train control system. In this circumstance, more safety is required than before in the railway system. In order to accomplish the safety of a system, the requirements considering safety have to be suggested. The requirement is a set of several functions such as general function, environment, safety etc. For the safety critical system, safety function is more important than any other functions. The safety functions are deduced by safety analysis. In order to perform the safety analysis, the system hazards have to be identified and then risk analysis for each hazard should be performed. The risk is related to the frequency and the severity of each hazard. And then countermeasures for each risk have to be prepared. The summary of the countermeasures is about a kind of safety functions in a system. In this paper, the safety functions for a train control system are presented according to the above procedure.

• Wind and Structures
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• 제20권2호
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• pp.143-168
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• 2015

A numerical model for analyzing air-train-track interaction is proposed to investigate the dynamic behavior of a high-speed train running on a track in crosswinds. The model is composed of a train-track interaction model and a train-air interaction model. The train-track interaction model is built on the basis of the vehicle-track coupled dynamics theory. The train-air interaction model is developed based on the train aerodynamics, in which the Arbitrary Lagrangian-Eulerian (ALE) method is employed to deal with the dynamic boundary between the train and the air. Based on the air-train-track model, characteristics of flow structure around a high-speed train are described and the dynamic behavior of the high-speed train running on track in crosswinds is investigated. Results show that the dynamic indices of the head car are larger than those of other cars in crosswinds. From the viewpoint of dynamic safety evaluation, the running safety of the train in crosswinds is basically controlled by the head car. Compared with the generally used assessment indices of running safety such as the derailment coefficient and the wheel-load reduction ratio, the overturning coefficient will overestimate the running safety of a train on a track under crosswind condition. It is suggested to use the wheel-load reduction ratio and the lateral wheel-rail force as the dominant safety assessment indices when high-speed trains run in crosswinds.

• 한국안전학회지
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• 제22권5호
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• pp.71-76
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• 2007

Failures of equipments for train control systems are linked directly to extensive damages of human lives or financial losses from the increasing uses of train control equipments utilizing computers. Then safety activities for assuring safety and reliability are needed during the system life-cycle. Risk analysis is important phase to increase safety from determining the risk presented by the identified hazard. In this paper, we investigated several methods for risk estimation of safety activities, and then we drew a comparison between original methods to suggest optimized one in the application to train control systems. In the result of the comparison, we had plan to propose the risk analysis method called Best-Practice(BP) risk method combining advantages of the qualitative and the quantitative analysis. In addition, we attempted to apply the BP-risk method to domestic train control systems handling in Korea.

• 한국안전학회지
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• 제38권1호
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• pp.87-92
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• 2023

The number of unmanned light rail train operators is continuously increasing in Korea. In a failure event during an operation due to the nature of the unmanned operation, recovery is performed based on the remote control. However, if remote recovery is not feasible, safety personnel arrive at the train to resume the train operation. There are regulations on safety personnel and the suspension time of the train operation. However, there is currently no rule for safety personnel deployment. Currently, railway operating organizations operate in three scenarios: safety personnel on board trains, stationed at stations, and deployed at major stations. Four major factors influence the downtime for each emergency response scenario. However, these four influencing factors vary too much to predict results with simple calculations. In this study, four influencing factors were considered as random variables with high uncertainty. In addition, the Monte Carlo method was applied to each scenario for the safety personnel deployment to predict train service downtime. This study found a 17% difference in train service suspension by safety personnel deployment scenario. The results of this study can be used in setting service goals, such as standards for future safety personnel placement and frequency of service interruptions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1556-1558
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• 2005

As a result of the advancement of radio communications technologies, some investigations are in progress to apply this technologies to a train control system. Most of these investigations are focused on the train safety distance control between a preceding train and a succeeding train, an interlocking system uses train circuits to control the railway path. To make the best use of advantages and improve the safety of radio communications based train control systems, the interlocking system must use radio communications technologies. And the safety level of this system must be equal to track circuit based interlocking systems. This paper describes the train location detection method, the system configuration and the system safety of the new system.

• 한국안전학회지
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• 제29권4호
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• pp.191-198
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• 2014

In the event of continued train operation being impossible as the result of a breakdown, it will be essential to dispatch a relief train to recover the broken down train. Operation of relief train carries with the risk of collision in the process of connection with broken down train. The present study looks at the suitability of risk management procedures and associated problems in the light of case studies of relief train operation, and of national legal standards and railroad company regulations. It looks at appropriate methods of risk management and the problems that can arise. Based on the study a method is proposed of operating the relief train which is consistent with appropriate risk management. The proposed method will improve the safety of relief train operation, It is hoped that the results of the study will be reflected in relevant laws and operating company regulations, and so contribute to enhancing the overall level of railroad safety.

• Structural Engineering and Mechanics
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• 제76권2호
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• pp.207-222
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• 2020

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train subjected to fluctuating crosswind. To ensure the safe operation in metro lines in mountain cities, running safety of the metro train over the high-pier bridge under crosswind is analyzed in this paper. Firstly, the dynamic model of the wind-train-bridge (WTB) system is built, in which the speed-up effect of crosswind is fully considered. On the basis of time domain analysis, the basic characteristics of the WTB system with high-pier are analyzed. Afterwards, the dynamic responses varies with train speed and wind speed are calculated, and the safety zone of metro train over a high-pier bridge subjected to fluctuating crosswind in mountain city is determined. The results indicate that, fluctuating crosswind triggers drastic vibration to the metro train and high-pier bridges, which in turn causes running instability of the train. For this reason, the corresponding safety zone for metro train running on the high-pier is proposed, and the metro traffic on the high-pier bridge should be closed as the mean wind speed of standard height reaches 9 m/s (15.6 m/s for the train).

• 대한안전경영과학회지
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• 제17권3호
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• pp.81-88
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• 2015

Infrastructure such as tracks, catenary, rolling stock and signaling systems, and close interface with the human factors of train drivers, shunting staff and maintenance staff are required for train operations. Safety management is the most essential part for the functioning of a train. In line with the safety management, each rail operator has a safety guidance system and the Ministry of Land, Infrastructure and Transport operates Railway Safety Inspector system. Safety Inspector System is to train employees working in the field to be aware of rules and regulations, and to improve identified risk factors. Hence, it is necessary to establish systematic training and inspection methods for safety guidance staff and make clear the roles and responsibilities of safety inspectors according to the Occupational Safety and Health Act, and safety instructors for several inspections according to the Railroad Safety Act.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.272-279
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• 2007

Recently, train control system is adopting computer system replacing mechanical system and its software is taking more responsibility than ever. Train control system software is a safety-critical embedded software with realtime and high reliability requirements. In this paper, we propose a safety assessment method for the train control system software. We review characteristics of train control system software and analyze related international software safety standards to derive requirements for safety assessment. Testing tools used for embedded software are surveyed to find a feasible safety assessment architecture. The proposed safety assessment method is to use safety activity results generated during development processes and feed them to the runtime embedded software testing tool.

• Structural Engineering and Mechanics
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• 제59권4호
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• pp.683-701
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• 2016

Safety is the prime concern for a high-speed railway bridge, especially when it is subjected to a collision. In this paper, an analysis framework for the dynamic responses of train-bridge systems under collision load is established. A multi-body dynamics model is employed to represent the moving vehicle, the modal decomposition method is adopted to describe the bridge structure, and the time history of a collision load is used as the external load on the train-bridge system. A (180+216+180) m continuous steel trussed-arch bridge is considered as an illustrative case study. With the vessel collision acting on the pier, the displacements and accelerations at the pier-top and the mid-span of the bridge are calculated when a CRH2 high-speed train running through the bridge, and the influence of bridge vibration on the running safety indices of the train, including derailment factors, offload factors and lateral wheel/rail forces, are analyzed. The results demonstrate that under the vessel collision load, the dynamic responses of the bridge are greatly enlarged, threatening the running safety of high-speed train on the bridge, which is affected by both the collision intensity and the train speed.