• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.41-46
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• 2017

The coefficient of derailment and the rate of wheel load reduction were used as the index of train running safety that was directly affected the train derailment safety. In aspects of track, the train running safety depends on the complex interaction between wheel and rail, and the track-vehicle conditions (i.e., the curvature, cant, track system, vehicle speed and the operation conditions, etc). In this study, the relationship between the train running safety and the track curvature and vehicle speed for direct fixation concrete tracks currently employed in Korean light rapid transit was assessed by performing field tests using actual vehicles running along the service lines. The measured dynamic wheel load, lateral wheel load and lateral displacement of rail head were measured for same train running on four tested tracks under real conditions, which included curved and tangent tracks placed on the tunnel and bridge, thus increasing the train speed by approximately maximum design speed of each test site. Therefore, the measured dynamic track response was applied to the running safety analysis in order to evaluate the coefficient of derailment, the rate of wheel load reduction and the track gauge widening at each test site, and compare with the corresponding Korean train running safety standard. As the results, the lateral track response of direct fixation concrete track appeared to increase with the decreased track curvature; therefore, it was inferred that the track curvature directly affected the train running safety.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.8
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• pp.941-949
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• 2011

When a railway vehicle passes through curves & transitions, the running speed must be improved by setting limits on the maximum running speed in each section of the conventional line(Dongdaegoo-Namsunghyun) considering derailment safety. Our goal is to improve the maximum running speed of railway vehicle that passes through curves & transitions where there is a high risk of derailment. We examined the influence on the derailment safety when the railway vehicle passes through curves of actual track conditions (Dongdaegoo-Namsunghyun up and down lines). We performed the derailment safety analysis by increasing the running speed on curve radius by 5%.20% compared to existing speed under actual track conditions.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.320-328
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• 2017

In order to analyze the influence on derailment safety according to the aging of primary rubber springs widely applied to railway vehicles, characteristic tests were carried out on aged primary rubber spring samples. To analyze the effect of primary rubber spring aging on derailment safety, a vehicle dynamic analysis was carried out. The results of the vertical characteristics test for the rubber spring specimens with 17 years of service life revealed that the displacement restoration function was degraded due to rubber aging and the spring stiffness significantly increased. The results of the running dynamic analysis simulating the twist track running in accordance with the EN14363 standard, compared with the normal vehicle model (Case 1), showed that the derailment coefficient and the wheel unloading of the vehicle model (Case 2) using the aging primary spring characteristic increased, and the derailment safety was degraded. IN particular, it was found that the derailment safety due to the reduction of the wheel load is weak in the transient section where a steep slope change occurs.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.12-15
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• 2005

In April 1, 2004, age of high-speed railway was opened to korea railroad. The railroad is a means of large transportation which has many talents such as a safety and a regularity. That is a results from various confidential performance tests and evaluations of the system. The railroad system consist of various subsystems - vehicle, power supply, signal, communications, track structures, operations, etc. Among them, as an item of safety evaluation there is a measurement of wheel/rail farce, so called a measurement of derailment coefficient. This is a very important item because a derailment of a train will bring about a big accident. Especially it is more important in high speed rail of which operation speed is over two times as fast as existing rail. In this paper, examined speed elevation possibility use the korean style high speed railway vehicle for reduce the running time of high-speed railway between high speed line and conventional line.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.1073-1074
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• 2009

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.959-964
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• 2007

In this study, it is offering a numerical method which assesses running safety of the freight car loaded CWR when passing through on the conventional railway by additional lateral load. It is suggested based on the numerical reviews of the safety against derailment after seeking the derailment coefficient estimated by wheel load-lateral force equation in the section that curve radius is small

• International Journal of Railway
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• v.4 no.2
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• pp.50-55
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• 2011

The dynamic stability of railway vehicle has long been one of the important issues in railway safety. The dynamic simulator has been used as a tool for investigating the dynamic stability of railway vehicles and wheel/rail interfaces. In particular, small scale simulators have been widely used in laboratory studies instead of full scale roller rigs which can be quite costly and rather inconvenient for testing out the effect of diverse design parameters. But techniques for design of a small scale simulator for the fundamental study about the dynamic characteristics of the wheel-rail systems and the bogie systems have not been well developed in Korea. Therefore, a research on the development of a small scale simulator for investigating bogie dynamics needs to be undertaken. The present paper investigates design of a small-scaled derailment simulator and the design of a small scale bogie. The simulator developed can be used to investigate the effect of diverse parameters such as attack angle, wheelbase and cant on dynamic behavior of the bogie and key dynamic performance parameters such as derailment coefficient and critical speed.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.145-151
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• 2018

In this study, the track-bridge interaction analysis was performed using an analytical model considering the track structure, thereby taking into account the linear conditions (R=650 m, cant variation $160{\pm}60mm$) and the dynamic characteristics of the bridge. As a result of the study, the allowable speed on the example bridge considered was calculated at 200 km/h based on vertical deflection, vertical acceleration, and irregularity in longitudinal level, but was also evaluated at 170km/h based on the coefficient of derailment, wheel load reduction, and lateral displacement of the rail head. It is considered desirable to set the speed 170km/h to the speed limit in order to secure the safety of both the bridge and the track. It is judged that there will be no problems with ensuring rail protection and train stability in the speed band.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.162-167
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• 2017

The chevron rubber spring is used for subway vehicle as a primary suspension. Generally, the primary suspension has an influence to the running performance and not so much effect on the ride comfort in railway vehicle. But the stiffness of chevron spring is harder and harder as time goes on because of rubber characteristics. Therefore the dynamic characteristics such as ride comfort and derailment coefficient should be reviewed according to the stiffness variation of chevron rubber spring. In this paper the effect of chevron rubber spring on dynamic characteristics was studied by considering multi-body dynamics of railway vehicle on one straight line and seven curved lines.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.363-364
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• 2006

The important factor to evaluate the running safety of a railway vehicle would be the interaction force between wheel and rail(derailment coefficient), for which is one of important factors to check the running safety of a railway vehicle that may cause a tragic accident. In this paper, when interaction force between wheel and rail happens to wheel-set of tilting vehicles, it analyzes stress distribution and verified safety.