• Title, Summary, Keyword: track irregularity

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Measurement and analysis of support stiffness of the track which rubber ballast-mat installed (방진자갈매트구간 궤도지지계수 측정 및 분석)

  • Yang, Shin-Chu;Lee, Jee-Ha;Kim, Eun
    • Proceedings of the KSR Conference
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    • pp.1071-1076
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    • 2007
  • In high-speed line, at some part of the track which rubber ballast-mat installed, track irregularity grew rapidly and affected riding comfort and train running stability. It is urgently requested to establish counter-measures which can be applied to track under operation. To do this, it is very important to analysis the origin of that phenomenon before. Track support stiffness is an essential factor for evaluating track condition. Sudden changes of support stiffness along track occur instability of train and bad riding comfort. Preventing sudden changes of track support stiffness is a key technique in high-speed track maintenance. Besides the sudden changes, the magnitude itself also significantly affects track and train. Low stiffness of ballast-mat makes ballast acceleration area wider. And it may accelerate track irregularity growth. So, the stiffness should be limited. To calculate track stiffness, measuring load and displacement on track is needed. In this study, the behavior of the track which rubber ballast-mat installed was measured and analyzed to understand the origin of rapid growth of it.

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Application of Time-Series Model to Forecast Track Irregularity Progress (궤도틀림 진전 예측을 위한 시계열 모델 적용)

  • Jeong, Min Chul;Kim, Gun Woo;Kim, Jung Hoon;Kang, Yun Suk;Kong, Jung Sik
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.4
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    • pp.331-338
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    • 2012
  • Irregularity data inspected by EM-120, an railway inspection system in Korea includes unavoidable incomplete and erratic information, so it is encountered lots of problem to analyse those data without appropriate pre-data-refining processes. In this research, for the efficient management and maintenance of railway system, characteristics and problems of the detected track irregularity data have been analyzed and efficient processing techniques were developed to solve the problems. The correlation between track irregularity and seasonal changes was conducted based on ARIMA model analysis. Finally, time series analysis was carried out by various forecasting model, such as regression, exponential smoothing and ARIMA model, to determine the appropriate optimal models for forecasting track irregularity progress.

Analysis of Short Grinding Effect on Removing of Surface Irregularities of Rail Welding Joint (레일용접부 요철 제거의 국부연마 효과 분석)

  • Woo, Byoung-Koo;Lee, Syeung-Yeol;Kim, Myung-Soo;Lee, Sung-Uk
    • Proceedings of the KSR Conference
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    • pp.684-691
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    • 2010
  • Rail is one of major track components for train service, it should be provided in the condition of flat and smooth driving aspect. Therefore, it is inevitable that there would be the field welding to integrate on CWR(Continuous Welded Rail) removing rail joint in these days. It is high chance to be some rail surface irregularity due to the limitation on the status of work condition If a high speed train runs on the rail surface irregularity in the welding part, big impact load comes to pass on that, so track irregularity cycle is reduced, therefore track maintenance cost can be increased. this paper has analyzed wheel load variation according to removing the rail surface irregularity using portable grinding machine in the high speed line. The result measured before and after in the field is decreased about 9.26% on the wheel load variation.

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Study for Progress Rate of Standard Deviation of Irregularity Based on Track Properties for the Railway Track Maintenance Cycle Analysis (궤도 유지보수 주기 예측을 위한 구간 특성에 따른 궤도틀림 표준편차 진전정도 분석)

  • Jeong, Min Chul;Kim, Jung Hoon;Lee, Jee Ha;Kang, Yun Suk;Kong, Jung Sik
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.3
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    • pp.31-40
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    • 2012
  • The irregularity of railway track affects not only the comfort of ride such as noise or vibration but also the safety of train operation. For this reason, it is an interesting research area to design a reliable and sustainable railway track system and to analyze the train movement mechanism based on systematic approaches considering reasons of track irregularity possible in a specific local environment. Irregularity data inspected by EM-120, an railway inspection system in Korea includes unavoidable incomplete and erratic information, so it is encountered lots of problem to analyse those data without appropriate pre-data-refining processes. In this research, for the efficient management and maintenance of railway system, progress rate of standard deviation of irregularity is quantified. During the computation, some important components of railways such as rail joint, ballast, roadbed, and fastener have been considered. Probabilistic distributions of irregularity growth with respect to time are computed to predict the remaining service life of railway track and to be adapted for the safety assessment.

Identification of Track Irregularity using Wavelet Transfer Function (웨이브렛 전달함수를 이용한 궤도틀림 식별)

  • Shin, Soo-Bong;Lee, Hyeung-Jin;Kim, Man-Cheol;Yoon, Seok-Jun
    • Journal of the Korean Society for Railway
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    • v.13 no.3
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    • pp.304-308
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    • 2010
  • This paper presents a methodology for identifying track irregularity using a wavelet transfer function. An equivalent wavelet SISO (single-input single-output) transfer function is defined by the measured track geometry and the acceleration data measured at a bogie of a train. All the measured data with various sampling frequencies were rearranged according to the constant 25cm reference recording distance of the track recording vehicle used in the field. Before applying the wavelet transform, measured data were regressed by eliminating those out of the range. The inverse wavelet transfer function is also formulated to estimate track geometry. The closeness of the estimated track geometry to the actual one is evaluated by the coherence function and also by FRF (frequency response function). A track irregularity index is defined by comparing the variance of the estimation error from the intact condition and that from the current condition. A simulation study has been carried out to examine the proposed algorithm.

The Effect of the Tied Sleeper on the Maintenance Work in the Rail Expansion Joint Zone (레일신축 이음부 유지보수 작업에 대한 침목결속의 영향)

  • Bae, Hyun-Ung;Kang, Tae-Ku;Choi, Jin-Yu;Jeong, Won-Ik;Lim, Nam-Hyoung
    • Proceedings of the KSR Conference
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    • pp.2125-2128
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    • 2011
  • The continuous welded rail(CWR) track without the rail expansion joint has many advantages over the conventional track in a variety of fields including the speed-up and the ride comport. However, due to the excessive axial force in the CWR and the track-bridge interactive behavior, inevitably, the rail expansion joint must be installed at the vulnerable zone such as the bridge end zone, etc. In this rail expansion joint zone, the frequency of the maintenance work to repair the track irregularity is on the rise. This is because that the creep of the sleeper is occurred in the moveable zone of the rail expansion joint. In this study, among the several options for reducing the track irregularity on the rail expansion joint zone, the application and efficiency of the tied sleeper is investigated. Field test construction has been conducted, then the progress of the track irregularity and the frequency of the maintenance work are analyzed before and after the filed test construction.

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A Bayesian Regression Model to Estimate the Deterioration Rate of Track Irregularities (궤도틀림 진전율 추정을 위한 베이지안 회귀분석 모형 연구)

  • Park, Bum Hwan
    • Journal of the Korean Society for Railway
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    • v.19 no.4
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    • pp.547-554
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    • 2016
  • This study considered how to estimate the deterioration rate of the track quality index, which represents track geometric irregularity. Most existing studies have used a simple linear regression and regarded the slope of the regression equation as the progress rate. In this paper, we present a Bayesian approach to estimate the track irregularity progress. This Bayesian approach has many advantages, among which the biggest is that it can formally include the prior distribution of parameters which can be derived from historic data or from expert experiences; then, the rate can be expressed as a probability distribution. We investigated the possibility of applying the Bayesian method to the estimation of the deterioration rate by comparing our bayesian approach to the conventional linear regression approach.

Correlation Analysis between Crack and TQI in RC Slab Track

  • Kwon, Se-Kon;Park, Mi-Yun;Kim, Doo-Kie;Sho, Byung-Choon;Park, Jae-Hak
    • International Journal of Railway
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    • v.7 no.1
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    • pp.8-15
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    • 2014
  • Recently, in the total railroad construction field, concrete slab tracks have been adapted in place of ballast tracks. Because ballast tracks need frequent maintenance and are difficult to handle due to increasing maintenance costs, eventually concrete slab tracks were selected as an alternative. However, owing to the hydration heat reactions and temperature-affected shrinkage of the concrete, a variety of studies to solve maintenance problems related to concrete slab tracks are underway. This study analyzed characteristics of TQI values evaluating track irregularity, investigated the relationship between crack progress and TQI, and then evaluated the correlation between the two values. Through our analysis, we found that there is a need to supplement the problems of the current method and develop a track evaluation index which takes cracking into account. We also concluded that TQI is the main decision-making tool in track maintenance.

Dynamic analysis of eddy current brake system for design evaluation (와전류 제동장치 설계검증을 위한 동역학적 해석)

  • Chung, Kyung-Ryul;T. Benker
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.318.1-318
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    • 2002
  • In this paper, the results of an analysis of the dynamic behavior of the eddy current brake(ECB) system are presented. The measured irregularity of the track in Korean high speed line and the track irregularity given by ERRI(high level) were used for simulation. The wheel-rail profile combination were analyzed with different rail gauges. A model of the bogie with an substitute body fur the carbody was implemented in the Multi-Body-Simulation Program Simpack. (omitted)

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Evaluation of Rail Fatigue Life by Rail Grinding in the High Speed Railway (레일연마에 따른 고속철도 레일 피로수명 평가)

  • Park, Won-Seo;Lim, Hyung-Jun;Park, Yong-Gul;Sung, Deok-Yong;Kang, Yoon-Suk
    • Proceedings of the KSR Conference
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    • pp.783-792
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    • 2011
  • The control of rail surface irregularity is very important for the high speed train service in the high speed rail. In order to manage it, initial, preventative, and maintainable rail grinding have been performed and among them, preventative rail grinding conducts in every each year. This study carried out the field test for dynamic track response according to rail surface irregularity comparing before and after rail grinding. In addition, the change of dynamic track responses according to rail grinding was analyzed and the fatigue life was estimated though Rainflow Counting Method and RMC Equivalence Stress. Therefore, it suggested that rail fatigue life should be increased by rail grinding, because amount of impact occurred on track is decreased by getting rid of rail surface irregularity.

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