• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1010-1015
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• 2009

Rail-pad is an important and readily replaceable component of a railway track, as it is the elastic layer between the rail and the sleeper. Characteristics and useful lifetime prediction of rail-pad was very important in design procedure to assure the safety and reliability. In order to investigate the useful lifetime, the accelerate test were carried out. Accelerated test results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the acceleration test, several useful lifetime prediction for rail-pads were proposed.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.442-449
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• 1999

Due to temperature variations, considerable longitudinal rail forces and displacements may develop in continuous welded rail(CWR) track on long-span bridges or viaducts. Excessive relative displacements between sleepers and ballast bed may disturb the stable position of the track in the ballast which results in a lower frictional resistance. Generally, these problems are solved by installing rail expansion devices. However the application of expansion devices in high-speed tracks on existing bridges, as a means to prevent excessive longitudinal displacements and forces, is not attractive method due to comfort, safety and maintenance aspects. An alternative and very effective solution is possibly the use of so-called zero longitudinal restraint(ZLR) fastenings over some length of the track. The calculations, carried out in this respect, show a considerable reduction of track displacements, track forces, and the relative sleeper/ballast displacements. This reduction depends on the length over which these fastenings are installed. In this paper calculations of the longitudinal displacments and forces in a CWR track and substructure resulting from thermal, mechanical and kinematical loads were carried out using the FEM analysis program LUSAS

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.1106-1111
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• 2002

The design of sleeper in high-speed railway turnouts is complicated and time-consuming because the length and loading position of sleepers change continuously along the turnout line. It is, therefore, necessary to develop an automated design program which can design automatically the PSC sleepers in turnout region. In this study, a computer program for automatic design of turnout sleepers was developed based on graphic user-interface(GUI) environment. The structural analysis is performed considering the varying loading position of vehicular wheels. The sleepers are treated as located on elastic supports. The user can choose the desirable shape of sleepers before starting the detail design. The present study allows more realistic and automatic design of PSC sleepers in high-speed railway turnouts.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.382-388
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• 2005

SMSC(Seoul Metropolitan Subway Corporation) is substantially taking the core role of mass transit system in Seoul Metropolitan area. When it was built, the design had challenged to sharp curved tracks less than 250m radius considering the protection of buildings and cultural properties as well as the connection to ground roads. Such circumstances have required a certain extent of slack in track geometry and therefore led to the construction of ballasted track with wooden sleepers. However, the dynamic force from running on sharp curved track has caused the misalignment and abnormal failure of track geometry, and it has resulted in a frequent maintenance and repair works which require a lot of cost and manpower. In this paper, we present the construction case of maintenance-free track system by using of concrete sleeper and elastic rail fastening system to ensure the safety of both passengers and trains, and to contribute the effective maintenance for track facilities of SMSC.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.487-494
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• 2000

For the rail fastener clip shoulder being used in Pandrol e-cilp type fastening system, there has been a need to make a structural and electrical improvement due to the fact that PC concrete sleeper showed material loss in the vicinity of exposed portion of the clip shoulder and the fact that track signal was lost when a track insulation block is missing on the track. In the present study, a new lightweight rail fastener clip shoulder with enhanced electrical insulation capability is developed

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.250-255
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• 2002

The transition between bridge and earthwork often causes the problems of maintenance. The damages of the track on the transition area influence running safety of train and serviceability, increase the maintenance cost. Therefore it is very important to evaluate the dynamic responses of transition and take a efficient measure. In order to evaluate the dynamic behavior of track, the field estimations are performed at the transition area of a conventional line between bridge and earthwork. And the track system on the transition area numerically analyzed to evaluate the dynamic behavior of damaged track with void sleeper. The measured values and Analysis results such as wheel contact force, rail stress, displacement acceleration and track irregularity in the transition area show the dynamic forces are severe. So it is recommended that the transition area should be improved the rigidity by reinforcing the rail.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1293-1298
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• 2006

A numerical analysis was performed to verify how much additional force is induced by short or long pitch rail corrugations in track. The rail corrugations assumed as sine wave having various pitches and depths. The variation of wheel force, displacement and acceleration of rail and sleeper was investigated. In the results, it was shown that each item of the investigation was increased as the pitches and depths become large. It is expected that the results of the parametric study can be used as a preliminary data for the determination of economical maintenance criteria for rail corrugation in the future

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.883-888
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• 2004

One of commercial rapid transits produces peculiar booming sound when passing through the slab-track tunnel. In order to analyze that tympanic membrane-pressing noise systematically, typical source-transfer path-response analysis was carried out. Considering the octave band of booming noise, work scope was confined to structure-borne noise analysis, especially the dynamic behaviour of railway tracks. Experimental modal analysis of railway tracks, composed of rail, rubber pad, sleeper, ballast, and ground were performed. The results shows that transversal bending modes of the rail are suspicious for the cause of the low band booming noise. Finite element analysis are made use of to match preceding experimental results, and plausible dynamic properties of track components are produced.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1056-1064
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• 2008

It is estimated that the running of locally-developed next generation High Speed Trains with maximum speed of 400km/h will help to deteriorate track components. It was presented rail defect coding system in UIC 712R includes the definitions of damage types of rail, maintenance procedures, and etc to detect and maintain. It is necessary to make a track maintenance manual determining track maintenance periods using the standardization of damage types of track components such as: sleeper, fastener, elastic pad. In this paper, the damage types of high speed track components are investigated by referring domestic and foreign literatures. And then the damage types of rail given in UIC 712R is reclassified more particularly and classified damage types of track components using internal high speed railway. In conclusion, this paper suggests standardization for damage types of track components on internal high speed railway.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.430-436
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• 2018

Special railway vehicles for track maintenance are equipped with a tamping device that adjusts various track trajectories to reduce the vibration of rolling stock and improve ride quality during trains passing over a track. The development of a simulator that can confirm the error of the actual tamping work is important for reducing human error in the linearization of the track misalignment. In this study, to improve the reality and training effect of conventional 2D simulator, 3D simulator modeling was implemented for tamping work of special railway vehicles in virtual space. The problem of buffering during high screen quality of tamping work was solved using the Unwrap UVW mapping technique of a low polygon extracted from high quality polygon modeling. The human error in the training of the tamping work was detected by the principle of circle and square collision when the tamping tyne and the sleeper collided. In addition, vibration of the driving chair was generated at the same time as the collision, and the number of the sleeper strikes is displayed on the simulator exercise screen. Owing to the scattering of railway ballast protruding from the sleepers, which had a serious effect on the safety of the vehicle, the gravel bouncing effect of the tamping unit was applied.