The Journal of Pandrol Rail Fastenings 2008 - Pandrol USA

DIRECT FIXATION ASSEMBLIESmaximum traffic frequency is 12 trains per hourduring peak hour operation. The track speedwas about 60km/h. All recordings were madeunder normal service passenger traffic with anaxle load of approximately 14 tonnes at peakoperating hours.Measurements with the existing baseplateswere made in December 2007. The PANDROLVANGUARD baseplates were installed inJanuary 2008 and then further trackmeasurements were made in February 2008.Vertical deflection of the rail relative to the slabincreased from about 0.31mm with the existingrail fastening to 3.11mm with the PANDROLVANGUARD system under the 14 tonnes axleload on Line 5 traffic. The maximum rail headlateral movement increased from 0.50mm to0.69mm, both occur on the low rail under theleading axle. This combination of low verticalstiffness and rail roll restraint with thePANDROL VANGUARD fastening system offersthe potential for significant reductions invibration transmission with a mechanicallyacceptable system. The railhead lateraldeflections indicated that the maximumdynamic track gauge widening for the existingfastening system and PANDROL VANGUARD isless than 1.0mm and less than 1.4mmrespectively. This meets the track maintenancespecification issued by China Ministry ofRailways in 1998, in which the dynamic trackgauge change should be within the toleranceof -6/+12mm for first class track under trainspeeds of less than 100km/h.SURFACE VIBRATIONPERFORMANCE OVER THETUNNEL WITH VANGUARDThe frequency range of greatest interest forsurface vibration is from 1Hz to 80Hz. Thevibration assessment is based on the ChineseNational Standards, GB10070-88 [3] andGB10071-88 [4] , in which the vibrationacceleration levels are weighted using thewindows defined in ISO2631-1 [5] . Vibration inthe vertical direction is represented in dBz.The vibration level was measured in aresidential property (145 Baimiaocun, FengtaiDistrict, Beijing) on the surface above thenorthbound tunnel on the same curved tracksite as for the track test – kilometre post ofK0+890m. The approximate position of thetwo tunnels is shown in Figure 3.Accelerometers were approximately 5.2m awayfrom the centreline of the northbound tunnel.Acceleration levels from trains on both thenorthbound and southbound tracks wererecorded, and were identified and separated.Vibration measurements vary considerably fromone train pass to the next, due to the effects ofspeed and rail-wheel condition. Trains wereselected from the recordings that appeared togive a clean signal. All vibration measurementspresented here have been averaged acrossresults from these selected train passes. Similarresults were obtained for all of the selectedtrains within each set of data.The average background surface vibrationlevel was about 52dBz in the vertical direction.The average vertical surface vibration level was76.3dBz and 73.4dBz with BJM baseplates, and64.2dBz and 58.1dBz with PANDROLVANGUARD baseplates in the northbound andsouthbound tunnels respectively. These indicatethat the surface vibration insertion loss was12.1dB and 15.2dB under traffic in thenorthbound and southbound tunnelsrespectively as the result of the installation ofPANDROL VANGUARD system. The averageinsertion loss was about 13.7dB over thecurved track. Vertical acceleration spectra atthe surface with the existing fastening and thePANDROL VANGUARD system installed areFigure 2(b) VANGUARD clamping5