• Proceedings of the KSR Conference
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• 2008.06a
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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.

• Proceedings of the KSR Conference
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• 2008.11b
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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.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.666-671
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• 2002

All work related to maintenance of track has been impletemented on the basis of the measured result from EM series cars in Korea. However, since these types of cars measure only versine value of the track irregularities instead of the real ones, this method will cause the confusion to maintenance operators if commercial speed should increase. This study was showing and explaining the program developed to get the real irregularities from the versine value. Finally, the reconstruction profiles completed by two different methods were compared with artificial track irregularities to confirm the their practicality.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2400-2404
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• 2011

Power spectral density (PSD) model of irregularities for the maglev test track is presented. Track irregularities (gauge, cant, twist and vertical) were calculated from the survey data of sleepers on the test track. PSD model was constructed from the estimated PSDs of each track irregularities. Versine (gauge, cant, twist, vertical and lateral) of the track is obtained and their PSDs were estimated, too. Presented PSD model can be used for the analysis of levitation stability and ride quality of the maglev system.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.989-995
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• 2010

This paper is focused on a simplified measurement of rail irregularity by some axle-box accelerometers for high-speed rail condition monitoring with in-service high-speed trains. Generally, the rail condition monitoring has been done by a special railway inspection vehicle with a 10m versine method. But, the monitoring method needs some expensive measurement system, and have been performed only at night due to its speed limit. In this research, a simplified measurement of rail irregularity using axle-box accelerometers is proposed to monitor the rail condition with in-service high-speed trains. The acceleration is measured by using two accelerometers on a axle-box, and stored in an on-board data acquisition system. The displacement is estimated from the acceleration data by a combination of Kalman filter and the frequency selective filter. The estimated results are compared with the measurement from a laser rail inspection system which is near the axle-box. From the comparison, the proposed method shows promise as a tool for the simplified measurement of rail irregularity at high-speed.

• Journal of the Korean Society for Railway
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• v.18 no.1
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• pp.63-70
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• 2015

Track irregularities have a strong influence on the safety and the ride comfort of trains as well as track maintenance work. A statistical analysis was conducted for track irregularities data measured in Kyoungbu high speed line using a track recording car(EM120). First, the characteristics of EM120, which adopted versine measurement system, were investigated and the transfer function of EM120 was examined. The distributions of the surface and the alignment which have short wavelength were considerably high and the distribution decreased as wavelength increases. A distribution analysis of the wavelength was carried out according to EN standards and most of the track irregularities were in a D1 wavelength range. The distributions of the amplitude of track irregularities were also investigated and the results show that the distributions of track irregularities decrease rapidly as amplitude increases. These results may be helpful in making track maintenance plans and revising track irregularities criteria.