• Title/Summary/Keyword: Track Geometry

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Monitoring in-service performance of fibre-reinforced foamed urethane sleepers/bearers in railway urban turnout systems

  • Kaewunruen, Sakdirat
    • Structural Monitoring and Maintenance
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    • v.1 no.1
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    • pp.131-157
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    • 2014
  • Special track systems used to divert a train to other directions or other tracks are generally called 'railway turnout'. A traditional turnout system consists of steel rails, switches, crossings, steel plates, fasteners, screw spikes, timber bearers, ballast and formation. The wheel rail contact over the crossing transfer zone has a dip-like shape and can often cause detrimental impact loads on the railway track and its components. The large impact also emits disturbing noises (either impact or ground-borne noise) to railway neighbors. In a brown-field railway track where an existing aged infrastructure requires renewal or maintenance, some physical constraints and construction complexities may dominate the choice of track forms or certain components. With the difficulty to seek for high-quality timbers with dimensional stability, a methodology to replace aged timber bearers in harsh dynamic environments is to adopt an alternative material that could mimic responses and characteristics of timber in both static and dynamic loading conditions. A critical review has suggested an application of an alternative material called fibre-reinforced foamed urethane (FFU). The full-scale capacity design makes use of its comparable engineering characteristics to timber, high-impact attenuation, high damping property, and a longer service life. A field trial to investigate in-situ behaviours of a turnout grillage system using an alternative material, 'fibre-reinforced foamed urethane (FFU)' bearers, has been carried out at a complex turnout junction under heavy mixed traffics at Hornsby, New South Wales, Australia. The turnout junction was renewed using the FFU bearers altogether with new special track components. Influences of the FFU bearers on track geometry (recorded by track inspection vehicle 'AK Car'), track settlement (based on survey data), track dynamics, and acoustic characteristics have been measured. Operational train pass-by measurements have been analysed to evaluate the effectiveness of the replacement methodology. Comparative studies show that the use of FFU bearers generates higher rail and sleeper accelerations but the damping capacity of the FFU help suppress vibration transferring onto other track components. The survey data analysis suggests a small vertical settlement and negligible lateral movement of the turnout system. The static and dynamic behaviours of FFU bearers appear to equate that of natural timber but its service life is superior.

Kinematic Modeling of a Track Trolley Using Extended Kalman Filter (확장 칼만필터를 이용한 궤도틀림 트롤리의 운동학적 모형화)

  • Lee, Jun S.;Choi, Il Yoon;Kim, Sun Hee;Um, Ju Hwan
    • Journal of the Korean Society for Railway
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    • v.18 no.5
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    • pp.447-456
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    • 2015
  • Continuous as well as discrete measurement of the track geometry based on a track trolley are investigated to enhance the efficiency of the trolley and to minimize the measurement errors. A new kinematic model based on the track coordinates involving transition and circular curves is developed to improve the accuracy of the measurement; a nonlinear Extended Kalman Filter (EKF) is employed to linearize the governing equations. The proposed model is verified with the ideal track geometry in terms of both discrete and continuous measurement. Comparison with the previous models is also made to prove the applicability of the kinematic model.

Practical Evaluation Technique for Deterioration of Railroad Lines using Track Geometry (철도노선 선형의 실용적 노후도 평가기법 개발)

  • Kim, Hyun Ki;Kim, Sung Jin;Choi, Chan Yong;Hwang, Soo Beom
    • Journal of the Korean Society for Railway
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    • v.17 no.2
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    • pp.106-113
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    • 2014
  • In this study, a practical evaluation technique to detect the deterioration of railroad lines by means of train performance and track geometry measures is suggested. A train that has a specific performance and is running the straight line can make minimum travel time (ideal time). But the actual travel time will be increased by the track geometry and various speed limitations. By comparing these travel times, we can easily define the degree of line deterioration. This method does not require complex vehicle performance measures and/or specifications that exceed those of typical Train Performance Simulations (TPS). For this reason, ease of use is ensured and the results are similar to those obtained by running a TPS for practical evaluations.

A Study on the Running Characteristic by Rail cant variation (레일 캔트 변화에 따른 주행특성에 관한 연구)

  • Eom, Beom-Gyu;Kim, Young-Gyu;Lee, Seung-Il;Lee, Hi-Sung
    • Proceedings of the KSR Conference
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    • 2011.05a
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    • pp.1142-1147
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    • 2011
  • The rail cant produces a wider bearing area between the wheel and the rail by moving the wheel-rail contact area away from the gauge towards the centre of the railhead, thus improving the wear pattern of the railhead and wheel treads. It is essential to keep the rail cant within the allowable range to ensure optimum track geometry. Neglecting the rail cant geometrical parameters in a track quality evaluation can cause safety of railway vehicle and serviceability problems. In this paper, we examined the effect of the rail cant in general geometry state of the railway track using VI-Rail and analyzed running safety when the railway vehicle passing through curves depending on change of the rail cant and running speed.

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A Running Safety Analysis of Railway Vehicle passing through Curve According to Rail Inclination Change (곡선부 통과열차의 레일 경좌 변화에 따른 주행안전성 해석)

  • Son, Myoung-Sun;Eom, Beom-Gyu;Kang, Bu-Byoung;Lee, Hi-Sung
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.1922-1928
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    • 2011
  • The rail inclination produces a wider bearing area between the wheel and the rail by moving the wheel rail contact area away from the gauge towards the centre of the railhead, thus improving the wear pattern of the railhead and wheel treads. It is essential to keep the rail inclination within the allowable range to ensure optimum track geometry. Neglecting the rail inclination geometrical parameters in a track quality evaluation can cause safety of railway vehicle and serviceability problems. In this paper, we examined the effect of the rail inclination in general geometry state of the railway track using VI-Rail and analyzed running safety when the railway vehicle passing through curves depending on change of the rail inclination and running speed.

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Development of the Computer System for the Analysis and the Management of Track Irregularities (궤도틀림의 분석 및 이력관리를 위한 전산시스템의 개발)

  • 오지택;백상욱
    • Proceedings of the KSR Conference
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    • 2000.11a
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    • pp.426-433
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    • 2000
  • The whole track system is designed and maintained to provide satisfactory geometry. Renewal and collection decisions are often governed by track irregularities. To provide cost-effective track to meet in the need in the future it is essential to be able to improve the methods by which the performance of the track is monitored and to have reliable methods for prediction and planning. This paper develops computer-aided system for analysis and management of track irregularities. The main objective is to collect and monitor track irregularities for each conventional line to be used as an aid in making decisions on track correction and renewal. The final decision especially on track renewal, however, always be a decision made by man and not by computer-aided system.

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Effect of temperature gradient on track-bridge interaction

  • Kumar, Rakesh;Upadhyay, Akhil
    • Interaction and multiscale mechanics
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    • v.5 no.1
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    • pp.1-12
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    • 2012
  • Considerable longitudinal rail forces and displacements may develop in continuous welded rail (CWR) track on long-span bridges due to temperature variations. The track stability may be disturbed due to excessive relative displacements between the sleepers and ballast bed and the accompanied reduction in frictional resistance. For high-speed tracks, however, solving these problems by installing rail expansion devices in the track is not an attractive solution as these devices may cause a local disturbance of the vertical track stiffness and track geometry which will require intensive maintenance. With reference to temperature, two actions are considered by the bridge loading standards, the uniform variation in the rail and deck temperature and the temperature gradient in deck. Generally, the effect of temperature gradient has been disregarded in the interaction analysis. This paper mainly deals with the effect of temperature gradient on the track-bridge interaction with respect to the support reaction, rail stresses and stability. The study presented in this paper was not mentioned in the related codes so far.

Design Loads on Railway Substructure: Sensitivity Analysis of the Influence of the Fastening Stiffness

  • Giannakos, Konstantinos
    • International Journal of Railway
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    • v.7 no.2
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    • pp.46-56
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    • 2014
  • The superstructure of the railway track undertakes the forces that develop during train passage and distributes them towards its seating. The track panel plays a key role in terms of load distribution, while at the same time it maintains the geometrical distance between the rails. The substructure and ballast undergo residual deformations under high stresses that contribute to the deterioration of the so-called geometry of the track. The track stiffness is the primary contributing factor to the amount of the stresses that develop on the substructure and is directly influenced by the fastening resilience. Four methods from the international literature are used in this paper to calculate the loads and stresses on the track substructure and the results are compared and discussed. A parametric investigation of the stresses that develop on the substructure of different types of railway tracks (i.e. balastless vs ballasted) is performed and the results are presented as a function of the total static track stiffness.

Evaluation on the condition and quality of railway track substructure (궤도노반의 상태 및 품질평가에 관한 연구)

  • Kim, Dae-Sang;Park, Tae-Soon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.346-353
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    • 2005
  • Track substructure(ballast, subgrade) should have sufficient strength and adequate stiffness to fully support track superstructure(rail, fastener, sleeper). Vertical support stiffness of track comes from the sufficient thickness, adequate strength and stiffness of material of substructure layers. Since the vertical support stiffness of track substructure is closely related with the track geometry, the evaluation of the stiffness is very important to understand the track states. This paper introduces the system, which are composed of Ground Penetrating Radar(GPR), Portable Ballast Sampler(PBS), and Light Falling Weight Deflectometer(LFWD), to evaluate substructure condition and summarizes the field test results performed with the reliable system.

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