• Title/Summary/Keyword: Track irregularity

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Post-earthquake track irregularity spectrum of high-speed railways continuous girder bridge

  • Feng, Yulin;Jiang, Lizhong;Zhou, Wangbao;Chen, Mengcheng
    • Steel and Composite Structures
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    • v.40 no.3
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    • pp.323-338
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    • 2021
  • To study the track irregularity spectrum for CRTS II ballastless track continuous girder bridge for high-speed railway (CBTCGB) after the action of earthquake, a line-bridge integration seismic calculation model was established. By considering the randomness of structural parameters and ground motion, large amounts of samples were analyzed for additional track irregularity caused by factors such as earthquake-induced damage and earthquake-induced void of key components between the layers of track-bridge system. Using improved Blackman-Turkey method and Levenberg- Marquardt algorithm, the earthquake damaged CBTCGB track irregularity spectrum, track irregularity spectrogram, and a fitting formula for track irregularity spectrum after the action of near-field earthquake were obtained, and the calculation results obtained from the fitting formula and CBTCGB numerical model were compared. The results indicate that the probability sampling distribution of ground motion and structural parameters selected according to "binning method" can effectively reflect the randomness of ground motion and structural parameters. The track irregularity spectrum line forms can be roughly divided into three ranges, namely, high-frequency, medium-frequency, and low-frequency waveband. The tracks suffer more track irregularity diseases with high-frequency after earthquake, which is necessary to conduct tracking analysis. It is rational to use a three-segment power function S(f)=AFg for the fitting of track irregularity spectrum after the action of earthquake.

A Study of Track Irregularity Standard for Rational Track Maintenance (일반철도 유지보수 합리화를 위한 궤도틀림 기준 연구방향)

  • Kim, Soo-Jeong;Lee, Byeong-Hyeok;Lee, Du-Jas;Eom, Jong-Woo
    • Proceedings of the KSR Conference
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    • pp.1624-1630
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    • 2011
  • Currently the train operating environment to affect track irregularity is changed rapidly such as speed-up, linear improvement and rolling stack upgrade. The recent track maintenance criteria of track irregularity was quoted from past Japan's, and the needs of revision of criteria are increased because of the rapid change in train operating environment. In case of enhance the track irregularity criteria, it secure driving safety and riding comfort but maintenance cost are increase. And also decrease ballast durability by frequent corrective work. In case of mitigate the criteria, it decrease driving safety and riding comfort, but save the maintenance cost. The study for enacting rational criteria did not carry out so far. In this study, survey the domestic and international track irregularity and case study for track irregularity inspection results and maintenance history for guideline of enacting irregularity criteria study.

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An Analysis of the Track Irregularity Progress on the Various Track System in Urban Transit (도시철도 궤도시스템별 틀림진전에 대한 분석)

  • Ko, Jae-Hyun;Kim, Man-Cheol;Lee, Jee-Ha;Cho, Jun-Gon;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • pp.311-319
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    • 2011
  • Track accompanies the process that track alignment by traffic loads is changed. A change of track alignment affects the running safety and riding comfort of train. This is called a track irregularity. The most important task in maintaining the track is to manage these track irregularity within quality parameters. Today, track maintenance of urban transit is enforcing immediate maintenance about section exceeding a safety standard by applying track recording data got through Integrated Measurement. This method is advantage of being easy of the maintenance assesment in case of the running safety, but is disadvantage of being difficult in case of the riding comfort of train. In this study, we propose track irregularity deviation of each track system depending on the time series and present about utilization plans of the Track Irregularity Progress Rate.

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Comparison of Track Recording with Surveying in Track irregularity Measurement (궤도틀림의 검측값과 측량결과 비교)

  • Lee, Jee-Ha;Choi, Ii-Yoon;Kim, Bak-Jin
    • Proceedings of the KSR Conference
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    • pp.1090-1095
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    • 2008
  • Track geometry changes by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, which determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from the characteristics of measuring device. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolley. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is EM-120, measures versine with 10m of symmetrical chord length.

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The Effect of the ZLR and Tied Sleeper to Reduce the Track Irregularity in the Bridge Expansion Joint Zone (교량신축부에서의 궤도틀림 저감을 위한 활동체결구 및 침목결속 효과)

  • Kang, Tae-Ku;Min, Kyung-Ju;Lim, Nam-Hyoung
    • Proceedings of the KSR Conference
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    • pp.2405-2408
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    • 2011
  • In recent time, the cause analysis and the reduction of the track irregularity have become the most important issue in the ballasted track on the high-speed railway bridge. This is because that the frequency of the maintenance work at the bridge expansion joint zone is on the rise. The track irregularity on the railway bridge starts at the end of the bridge-deck and spreads along the bridge. Due to the dynamic vibration and the thermal expansion of the bridge, the compaction of the ballast gravel on the bridge expansion joint zone become loose and then the progress of the track irregularity result from the train-induced dynamic impact is accelerating further. Among the several options for reducing the track irregularity on the bridge expansion joint zone, the application and efficiency of the zero longitudinal restraint(ZLR) and tied sleeper are investigated in this paper. 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. Of the two methods, it is shown that the installation of the ZLR seems to be better than the tied sleeper.

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Comparison of Chord method with Surveying in Track irregularity Measurement (측량과 현방식 궤도틀림 측정 비교)

  • Lee, Jee-Ha;Lee, Sang-Jin
    • Proceedings of the KSR Conference
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    • pp.1647-1652
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    • 2008
  • Track geometry consists of tangent and curved lines, which caused undesirable changes in initial track geometry by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To be able to objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, this method determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from specific property of measuring tool. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolly. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is Trackmaster, measures versine with 2m of chord length.

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Estimation of track irregularity using NARX neural network (NARX 신경망을 이용한 철도 궤도틀림 추정)

  • Kim, Man-Cheol;Choi, Bai-Sung;Kim, Yu-Hee;Shin, Soob-Ong
    • Proceedings of the KSR Conference
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    • pp.275-280
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    • 2011
  • Due to high-speed of trains, the track deformation increases rapidly and may lead to track irregularities causing the track stability problem. To secure the track stability, the continual inspection on track irregularities is required. The paper presents a methodology for identifying track irregularity using the NARX neural network considering non-linearity in the train structural system. A simulation study has been carried out to examine the proposed method. Acceleration time history data measured at a bogie were re-sampled to every 0.25m track irregularity. In the simulation study, two sets of measured data were simulated. The second data set was obtained by a train with 10% more mass than the one for the first data set. The first set of simulated data was used to train the series-parallel mode of NARX neural network. Then, the track irregularities at the second time period are identified by using the measured acceleration data. The closeness of the identified track irregularity to the actual one is evaluated by PSD and RMSE.

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Influence of track irregularity on train and track behaviours on high speed rail (차량고속주행시 차량 및 궤도거동에 미치는 궤도틀림의 영향)

  • 이진욱;양신추;홍진완
    • Proceedings of the KSR Conference
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    • pp.307-314
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    • 1998
  • In this paper, a numerical method for analyzing the interactions between train and track is presented. The effect of track irregularity on high speed running trains and track is examined by parametric studies. Two types of vertical track irregularity are considered. The first one is ideally assumed to a sine wave to investigate train and track behaviors with the change of its shape feasibly, The second one is artificially generated from PSD of track irregularity which was established from the measured data on real railways. In the track dynamic model, rail is considered to have a distributed mass and to be supported discretely at sleepers above ballast divided into three layers. Then, the contact between wheel and rail is modeled by a nonlinear Hertzian spring.

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Track Irregularity Inspection Method for Commercial Vehicle (영업차량에서의 궤도비틀림 검측 방안 연구)

  • Lee Chan-Woo;Choi Eun-Young
    • Proceedings of the KSR Conference
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    • pp.768-773
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    • 2003
  • The inspection of track irregularity, which is the most important index for the evaluation of the dynamic safety of the rolling stock, is performed by setting up the testing train set. The self-diagnosis for the various rolling stocks and railways can be obtained if it is possible to take the simultaneous inspection of track irregularity for the commercial vehicle while it is running and to build up a dynamic safety evaluation system. It is expected to have some good effects, such as preventing accident with the low dynamic safety, cutting cost for the testing train set and evaluating the exact influence on the rolling stock and railway. In this study, innertial measuring method, which allows us to directly measure the track irregularity from the commercial vehicle, will be considered and some overseas cases will be explored as well.

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Evaluation of Track irregularity due to Adjacent Excavation Work on Serviced Urban Transit (도시철도 인접굴착공사에 따른 운행선 궤도의 궤도틀림 분석)

  • Choi, Jung-Youl;Lee, Ho-hyun;Kang, You-Song;Chung, Jee-Seung
    • The Journal of the Convergence on Culture Technology
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    • v.6 no.2
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    • pp.481-487
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    • 2020
  • In this study, finite element analysis was performed to evaluate the track irregularity of the existing track system on urban transit according to the large-scale excavation work that is constructed adjacent to the serviced line. Based on the numerical analysis, the effect of track irregularity generated during the step-by-step construction process was analytically derived, and the stability in terms of track deformation was evaluated through comparison with related standards. As the results, in the case of track irregularity items evaluated based on the relative displacement difference at a certain distance, such as alignment and vertical irregularity, it occurred most clearly at the location where deformation of the existing structure begins, such as the end point of adjacent excavation work. On the other hand, the overall vertical and horizontal displacement of the track was the largest deformation at the center of the construction section. The vulnerable position of the deformed side of the existing structure due to adjacent excavation is analytically proven that the both of the end point section and the center of the construction can be a vulnerable position in terms of track irregularity.