Discussion On The Influence Of CP? Point Error On Track Regularity

Because of the measurement error, the coordinates of repetition measurement of CPIII points have changed, it will have an effect on the stationing coordinates of the survey station. That also will change the measured coordinates of the track points. In the Chinese Standard 'Code for engineering survey of high speed railway', the limited difference values of X, Y and Z of CPIII point between the repetition measurement and the original measurement should meet ±3.0 mm respectively. Also, the limited difference values of ?X,?Y and ?Z of adjacent CPIII point between the repetition measurement and the original measurement should meet ±2.0 mm respectively. If the difference values of coordinates of CPIII points between the repetition measurement and the original measurement meet the tolerance, the original coordinates of CPIII points cannot be replaced. The difference between coordinates of repetition measurement CPIII point and the coordinates of original CPIII point can give the degree of influence to the track regularity, which is worth being investigated. This thesis integrates the adjustment model of free-station of the GEDO CE system. The data of track point update model can be able to program. The three-dimensional coordinates of the center-lines points and designed coordinates of track points can be calculated using the measured three-dimensional coordinates of track points. The test analyses the effects of the change of CPIII coordinates and elevation to track irregularities through the experimental data. Simulating the offset of CPIII which perpendicular to the line tangent, to analysis of the change of coordinates of station, and then further analyze the impact of lateral and vertical deviations of track points, the change of lateral profile and vertical profile. The statistics are shown as follow:Firstly, When the offset of station observation is ±3.00 mm measured by 8 CPIII point coordinate component X, Y and Z deviation in the measurement coordinate system, If the CP III measurement coordinate system and track tangential coordinates system have (n?/2+?/4)(n= 0,2) angle relationship, the transverse offset of station can be up to ±4.24 mm.Secondly, When the CPIII measurement coordinate system and track tangential coordinates system have (n?/2+?/4)(n= 0,2) angle relationship, the value of 10 m and 30 m chord for lateral profile base on the changed CPIII points coordinates minus the value before the track point data changed. The maximum difference value of 10 m chord lateral profile is 0.60 mm. The maximum difference value of 30 m chord lateral profile is 0.80mm. When measuring the difference in elevation of variation is 3.00 mm, the value of 10 m and 30 m chord for vertical profile minus the value before the track point data changed, the maximum difference value of vertical profile of 10 m chord is 0.50 mm. the maximum difference value of vertical profile of 30 m chord is 0.60mm. Which of above appear in the track-data overlapping section.According to the analysis results above mentioned that it is necessary to restrain the tolerance value of lateral profile and vertical profile for 10 m and 30 m chord. The best way is to change the tolerance from ±2.0 mm to ± 1.2mm of the restrain the tolerance value of lateral profile and change the tolerance from ±2.0 mm to ± 1.4mm of the restrain the tolerance value of vertical profile. Even if the difference in coordinates of CPIII before and after retest can meet the requirement of tolerance, the track regularity cannot overrun.