scholarly journals Track – Bridge Interaction on High Speed Railways – the ONCF Experience

2019 ◽  
Vol 8 (4) ◽  
pp. 4607-4612
Keyword(s):  
High Speed ◽  
Study Phase ◽  
Limit Values ◽  
Temperature Variations ◽  
Track Geometry ◽  
Geometry Measurement ◽  
Track Bridge ◽  
Continuously Welded Rail ◽  
To Receive ◽  
Current Standards

This paper aims to describe the Moroccan experience on Track – Bridge interaction in railway domain. In fact, that phenomenon may induce a general track instability compromising train security if it’s not taken into account in the study phase. To that end, a numerical method, used to compute the additional longitudinal stresses on a continuously welded rail (CWR) mainly associated to relative displacements between track and deck on account of temperature variations, is presented. Therefore, the conditions of laying an expansion device will be concluded, particularly when the additional rail stresses exceed the maximum limit values defined on the current standards. An application of that method will be performed on MHARHAR viaduct where a non-compliance of track dilatation device laying was noticed. This study will emphasize the beginning of a track grid general instability due to ballast layer deconsolidation, the all based on a track geometry measurement. This study may be widely used in order to conceive properly a bridge supposed to receive a CWR track.

scholarly journals Identification of Temperature-Induced Deformation for HSR Slab Track Using Track Geometry Measurement Data

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5446 ◽  
Author(s):  
Zai-Wei Li ◽  
Xiao-Zhou Liu ◽  
Yue-Lei He
Keyword(s):  
High Speed ◽  
Detection Method ◽  
Measurement Data ◽  
Railway Track ◽  
Discrete Wavelet ◽  
High Speed Rail ◽  
Track Geometry ◽  
Slab Track ◽  
Geometry Measurement ◽  
Inspection Data

Slab track is widely used in many newly built high-speed rail (HSR) lines as it offers many advantages over ballasted tracks. However, in actual operation, slab tracks are subjected to operational and environmental factors, and structural damages are frequently reported. One of the most critical problems is temperature-induced slab-warping deformation (SWD) which can jeopardize the safety of train operation. This paper proposes an automatic slab deformation detection method in light of the track geometry measurement data, which are collected by high-speed track geometry car (HSTGC). The characteristic of track vertical irregularity is first analyzed in both time and frequency domain, and the feature of slab-warping phenomenon is observed. To quantify the severity of SWD, a slab-warping index (SWI) is established based on warping-sensitive feature extraction using discrete wavelet transform (DWT). The performance of the proposed algorithm is verified against visual inspection recorded on four sections of China HSR line, which are constructed with the China Railway Track System II (CRTSII) slab track. The results show that among the 24,806 slabs being assessed, over 94% of the slabs with warping deformation can be successfully identified by the proposed detection method. This study is expected to provide guidance for efficiently detecting and locating slab track defects, taking advantage of the massive track inspection data.

scholarly journals The Influence of an Integration Time Step on Dynamic Calculation of a Vehicle-Track-Bridge under High-Speed Railway

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 431
Author(s):  
Junjie Ye ◽  
Hao Sun
Keyword(s):  
High Speed ◽  
Coupled Model ◽  
Short Wave ◽  
Integration Time ◽  
Vertical Acceleration ◽  
Dynamic Calculation ◽  
Time Step ◽  
High Speed Railway ◽  
Track Irregularity ◽  
Track Bridge

In order to study the influence of an integration time step on dynamic calculation of a vehicle-track-bridge under high-speed railway, a vehicle-track-bridge (VTB) coupled model is established. The influence of the integration time step on calculation accuracy and calculation stability under different speeds or different track regularity states is studied. The influence of the track irregularity on the integration time step is further analyzed by using the spectral characteristic of sensitive wavelength. According to the results, the disparity among the effect of the integration time step on the calculation accuracy of the VTB coupled model at different speeds is very small. Higher speed requires a smaller integration time step to keep the calculation results stable. The effect of the integration time step on the calculation stability of the maximum vertical acceleration of each component at different speeds is somewhat different, and the mechanism of the effect of the integration time step on the calculation stability of the vehicle-track-bridge coupled system is that corresponding displacement at the integration time step is different. The calculation deviation of the maximum vertical acceleration of the car body, wheel-sets and bridge under the track short wave irregularity state are greatly increased compared with that without track irregularity. The maximum vertical acceleration of wheel-sets, rails, track slabs and the bridge under the track short wave irregularity state all show a significant declining trend. The larger the vibration frequency is, the smaller the range of integration time step is for dynamic calculation.

scholarly journals Identification of Sleeper Support Conditions Using Mechanical Model Supported Data-Driven Approach

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3609
Author(s):  
Mykola Sysyn ◽  
Michal Przybylowicz ◽  
Olga Nabochenko ◽  
Lei Kou
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Dynamic Interaction ◽  
Theoretical Research ◽  
Rolling Stock ◽  
Monitoring Methods ◽  
Beam Dynamic ◽  
Track Geometry ◽  
Data Driven Approach ◽  
Support Conditions

The ballasted track superstructure is characterized by a relative quick deterioration of track geometry due to ballast settlements and the accumulation of sleeper voids. The track zones with the sleeper voids differ from the geometrical irregularities with increased dynamic loading, high vibration, and unfavorable ballast-bed and sleeper contact conditions. This causes the accelerated growth of the inhomogeneous settlements, resulting in maintenance-expensive local instabilities that influence transportation reliability and availability. The recent identification and evaluation of the sleeper support conditions using track-side and on-board monitoring methods can help planning prevention activities to avoid or delay the development of local instabilities such as ballast breakdown, white spots, subgrade defects, etc. The paper presents theoretical and experimental studies that are directed at the development of the methods for sleeper support identification. The distinctive features of the dynamic behavior in the void zone compared to the equivalent geometrical irregularity are identified by numeric simulation using a three-beam dynamic model, taking into account superstructure and rolling stock dynamic interaction. The spectral features in time domain in scalograms and scattergrams are analyzed. Additionally, the theoretical research enabled to determine the similarities and differences of the dynamic interaction from the viewpoint of track-side and on-board measurements. The method of experimental investigation is presented by multipoint track-side measurements of rail-dynamic displacements using high-speed video records and digital imaging correlation (DIC) methods. The method is used to collect the statistical information from different-extent voided zones and the corresponding reference zones without voids. The applied machine learning methods enable the exact recent void identification using the wavelet scattering feature extraction from track-side measurements. A case study of the method application for an on-board measurement shows the moderate results of the recent void identification as well as the potential ways of its improvement.

scholarly journals The Design and Implementation of an Inertial GNSS Odometer Integrated Navigation System Based on a Federated Kalman Filter for High-Speed Railway Track Inspection

2021 ◽  
Vol 11 (11) ◽  
pp. 5244
Author(s):  
Xinchun Zhang ◽  
Ximin Cui ◽  
Bo Huang
Keyword(s):  
Kalman Filter ◽  
Navigation System ◽  
High Speed ◽  
Measurement Accuracy ◽  
Railway Track ◽  
Filter Method ◽  
Integrated Navigation ◽  
High Speed Railway ◽  
Track Geometry ◽  
Integrated Navigation System

The detection of track geometry parameters is essential for the safety of high-speed railway operation. To improve the accuracy and efficiency of the state detector of track geometry parameters, in this study we propose an inertial GNSS odometer integrated navigation system based on the federated Kalman, and a corresponding inertial track measurement system was also developed. This paper systematically introduces the construction process for the Kalman filter and data smoothing algorithm based on forward filtering and reverse smoothing. The engineering results show that the measurement accuracy of the track geometry parameters was better than 0.2 mm, and the detection speed was about 3 km/h. Thus, compared with the traditional Kalman filter method, the proposed design improved the measurement accuracy and met the requirements for the detection of geometric parameters of high-speed railway tracks.

Stochastic Transverse Earthquake-Induced Damage Track Irregularity Spectrum Considering the Uncertainty of Track-Bridge System

2021 ◽  
pp. 2140004
Author(s):  
Yulin Feng ◽  
Yu Hou ◽  
Lizhong Jiang ◽  
Wangbao Zhou ◽  
Jian Yu ◽  
...  
Keyword(s):  
Simulation Model ◽  
Traffic Safety ◽  
High Speed ◽  
Residual Deformation ◽  
High Speed Railway ◽  
Marquardt Algorithm ◽  
Earthquake Action ◽  
Track Irregularity ◽  
Track Bridge ◽  
Bridge System

The track irregularity spectrum of longitudinally connected ballastless track (LCBT)-bridge systems of high-speed railway was proposed in this paper. First, a simulation model of an LCBT-continuous girder bridge was established by considering the influences of approach bridges and subgrade with track structure. Further, a large number of sample analyses were carried out by taking into account the uncertainty of LCBT-bridge systems and stochastic behaviors of ground motions based on the simulation model. The damage laws of residual deformation of track-bridge system after earthquake actions were studied. Then, an interlayer deformation coordination relationship (IDCR) considering the track irregularity caused by earthquake-induced damage of bearings was developed, and the superposed track irregularity samples were obtained. Finally, by using the improved Blackman–Turkey method and Levenberg–Marquardt algorithm, the LCBT irregularity spectrum, track irregularity spectrogram, track irregularity limit spectrum, and a fitting formula for the track irregularity spectrum on a bridge after the action of earthquakes were obtained. Results obtained from the fitting formula and IDCR were compared, and they indicated that tracks undergone significant high-frequency irregularity diseases after the earthquake action. It was found that the track irregularity spectrum could be roughly divided into three ranges: high-, medium- and low-frequency wavebands. Consequently, this led to an application of a three-segment power function for the fitting of the track irregularity spectrum after the earthquake action. The track irregularity spectrum after the action of earthquakes provides an important theoretical basis for the establishment of seismic design methods for high-speed railway bridges based on the traffic safety performance.

Railway track irregularity and curvature estimation using doppler LIDAR fiber optics

2016 ◽  
Vol 232 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Masood Taheri Andani ◽  
Andrew Peterson ◽  
Josh Munoz ◽  
Mehdi Ahmadian
Keyword(s):  
Fiber Optics ◽  
Field Testing ◽  
Railway Track ◽  
Vehicle Speed ◽  
Doppler Lidar ◽  
Close Match ◽  
Track Geometry ◽  
Lidar Measurements ◽  
Curvature Estimation ◽  
Geometry Measurement

The application of Doppler-based LIght Detection and Ranging (LIDAR) technology for determining track curvature and lateral irregularities, including alignment and gage variation, are investigated. The proposed method uses track measurements by two low-elevation, slightly tilted LIDAR sensors nominally pointed at the rail gage face on each track. The Doppler LIDAR lenses are installed with a slight forward angle to measure track speed in both longitudinal and lateral directions. The lateral speed measurements are processed for assessing the track gage and alignment variations, using a method that is based on the frequency bandwidth dissimilarities between the vehicle speed and track geometry irregularity. Using the results from an extensive series of tests with a body-mounted Doppler LIDAR system on-board a track geometry measurement railcar, the study indicates a close match between the LIDAR measurements and those made with existing sensors on-board the railcar. The field testing conducted during this study indicates that LIDAR sensors could provide a reliable, non-contact track monitoring instrument for field use in various weather and track conditions, potentially in a semi-autonomous or autonomous manner.

Optimizing Tamper Efficiency Through the Integration of Inertial Based Track Geometry Measurement

2017 ◽  
Author(s):  
Joseph W. Palese ◽  
Sergio DiVentura ◽  
Ken Hill ◽  
Peter Maurice
Keyword(s):  
Time Perspective ◽  
Cloud Service ◽  
New Method ◽  
Maximum Efficiency ◽  
Track Geometry ◽  
Track Maintenance ◽  
Measurement Systems ◽  
Recorded Data ◽  
Available Technology ◽  
Geometry Measurement

Maintaining track geometry is key to the safe and efficient operations of a railroad. Failure to properly maintain geometry can lead to costly track structure failures or even more costly derailments. Currently, there exists a number of different methods for measuring track geometry and then if required, maintaining the track to return track geometry to specified levels of acceptance. Because of this need to have proper track geometry, tampers are one of the most common pieces of maintenance equipment in a railroad operation’s fleet. It is therefore paramount from both a cost and track time perspective to gain maximum efficiency from any one particular tamper. Track geometry is typically measured through a variety of contact and non-contact measurement systems which can mount on a variety of different platforms. With respect to a tamper, a push buggy projector system is typically used to measure track geometry, utilizing the tamper body as the basis for the reference system, Track geometry can be measured utilizing this technology during a prerecording run. Then, the software onboard the tamper analyzes the recorded data to determine the best fit and calculate throws that achieve a better track alignment, particularly in curves. During the tamping operation, the tamper buggy system and frame adjust the track. Due to its design, track geometry measurements can only be made at low speed (roughly 4mph) which can severely affect the efficiency of the tamper. To help decrease pre maintenance inspection times, an inertial based track geometry measurement system has been developed and integrated into the tamper’s operating software. This system can mount directly to the frame of a tamper and operate at hy-rail to very low speeds. Measurements made can be fed directly into the tamper control system to guide where and how track geometry adjustments need to be made. In addition, the capability to collect data during travel mode without the buggies extended allows for the collection of data at any time. Thus, data can be recorded when traveling back and forth to a stabling location, before and/or after grinding. This allows for synchronization of data at a later time to utilize for adjusting the track. Also, data can be collected post-work to allow for the comparison of pre and post geometry to allow for the determination of the effectiveness of a given tamping operation. Tampers equipped with this track geometry system facilitate the foundation for an enterprise solution. Data that is measured and collected can be sent to a cloud service, in real time that will provide exception reports, health status, and rail health trend analyses. Utilizing the available technology further optimizes response time in track maintenance. This paper will introduce this new method of mounting and completely integrating an inertial based track geometry system onto a tamper. In addition, studies will be presented which confirm the ability of this system to replicate the tamper’s projection based track geometry system. Finally, a comprehensive study on efficiency gains will be presented directly comparing a standard method of maintaining a segment via a tamper to this new method of using onboard inertial track geometry measurement.

scholarly journals PMD Study & Measurement – Fixed Analyzer Method

2015 ◽  
Vol 11 (4) ◽  
pp. 199 ◽  
Author(s):  
Rastislav Motuz ◽  
Petr Munster ◽  
Miloslav Filka
Keyword(s):  
Optical Networks ◽  
High Speed ◽  
Polarization Mode Dispersion ◽  
Main Attention ◽  
Laboratory Equipment ◽  
Limit Values ◽  
Mode Dispersion ◽  
Compensation Methods ◽  
Accuracy Of Measurements ◽  
Modular Platform

The paper theoretically describes Polarization Mode Dispersion (PMD) which is important parameter in high-speed optical networks. Furthermore, compensation methods and measurement principles are presented. Main attention is given to Fixed Analyzer (FA) method that uses common research laboratory equipment in setup. We performed practical measurement of the PMD by using Optical Spectrum Analyzer (OSA) Anritsu MS9740A, in-line polarizers and a polarization controller. To verify the accuracy of measurements Reference Measurement (RM) using a modular platform EXFO FTB-200 in combination with CD/PMD module EXFO FTB-5700 was performed. Moreover, PMD etalons with defined values of delay was used for measurement. All results were evaluated in comparison with defined limit values.

Nonlinear Vibration and Comfort Analysis of High-Speed Trains Moving Over Railway Bridges

Volume 2 ◽  
2004 ◽  
Author(s):  
M. H. Kargarnovin ◽  
D. Younesian ◽  
D. J. Thompson ◽  
C. J. C. Jones
Keyword(s):  
High Speed ◽  
Ride Comfort ◽  
Beam Theory ◽  
Maximum Acceleration ◽  
Railway Bridges ◽  
Comfort Index ◽  
Power Spectral ◽  
High Speed Trains ◽  
Train Speed ◽  
Track Bridge

The ride comfort of high-speed trains passing over railway bridges is studied in this paper. The effects of some nonlinear parameters in a carriage-track-bridge system are investigated such as the load-stiffening characteristics of the rail-pad and the ballast, rubber elements in the primary and secondary suspensions systems. The influence of the track irregularity and train speed on two comfort indicators, namely Sperling’s comfort index and the maximum acceleration level, are also studied. Timoshenko beam theory is used for modelling the rail and bridge and two layers of parallel damped springs in conjunction with a layer of mass are used to model the rail-pads, sleepers and ballast. A randomly irregular vertical track profile is modelled, characterised by a power spectral density (PSD). The ‘roughness’ is generated for three classes of tracks. Nonlinear Hertz theory is used for modelling the wheel-rail contact.

Shared Corridors, Shared Interests

2011 ◽  
Author(s):  
Allan M. Zarembski ◽  
James Blaze ◽  
Pradeep Patel
Keyword(s):  
High Speed ◽  
Safety Issue ◽  
Surface Profile ◽  
Physical Property ◽  
Passenger Train ◽  
Track Geometry ◽  
Track Maintenance ◽  
Trade Offs ◽  
Passenger Trains ◽  
Grade Crossings

What are some of the practical obstacles to a “shared interests” between a freight railway business and the proposed new higher speed passenger entity? This paper discusses the real “tension” between the two business interests that fund freight trains versus those that support and fund higher speed passenger trains as they attempt to share the same tracks in a safe manner. There are fundamental laws of physics that have to be addressed as the two different sets of equipment are “accommodated” on a shared corridor. This may not always be an easy accommodation between the two commercial parties. One real tension between the two commercial interests involves the physical problem of accommodating two radically different train sets on areas of curved track. For one example, what will be the passenger train required future higher speeds and how will these speeds be accommodated in existing main line tracks with curves varying from 1% to 6% in degrees? How much super elevation will need to be put back into the heretofore freight train tracks? How will the resulting super elevation affect the operation of so called drag or high tonnage slow speed bulk cargo trains? Accommodating such differences in train set types, axle loadings, freight versus passenger train set speeds, requires making detailed choices at the engineering level. These may be shared interests, but they are also variables with far different outcomes by design for the two different business types. The freight railways have spent the last few decades “taking the super elevation out” because it is not needed for the modern and highly efficient freight trains. Now the requirements of the passenger trains may need for it to be replaced. What are the dynamics and fundamental engineering principles at work here? Grade crossings have a safety issue set of interests that likely require such things as “quad” gates and for the highest passenger train speeds even complete grade separation. Track accommodating very high speed passenger trains requires under federal regulations much closer physical property tolerances in gauge width, track alignment, and surface profile. This in turn increases the level of track inspection and track maintenance expenses versus the standard freight operations in a corridor. Fundamentally, how is this all going to be allocated to the two different commercial train users? What will be the equally shared cost and what are examples of the solely allocated costs when a corridor has such different train users? In summary, this paper provides a description of these shared issues and the fundamental trade-offs that the parties must agree upon related to overall track design, track geometry, track curvature, super elevation options, allowed speeds in curves, more robust protection at grade crossings, and the manner in which these changes from the freight only corridors are to be allocated given the resulting much higher track maintenance costs of these to be shared assets.

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