On-line rail milling technologies have been applied in rail maintenance,and are proving to be efficient and environmental friendly.Based on the field data of on-line rail milling,a program for comparing rail transverse profiles before and after milling was designed and the root mean square(RMS)amplitude of longitudinal profile was calculated.The application of on-line rail milling technology in removing rail surface defects,re-profiling railhead transverse profiles,smoothing longitudinal profiles and improving welding joint irregularity were analyzed.The results showed that the on-line rail milling technology can remove the surface defects at the rail crown and gauge corner perfectly,re-profile railhead transverse profile with a tolerance of-1.0-0.2 mm,improve longitudinal irregularity of rail surface,with the RMS amplitude of irregularity reduced more than 50% and the number of out-of-limited amplitude reduced by 42%-82% in all wavelength ranges.The improvement of welding joint irregularity depends on the amount of metal removal determined by the milling equipment and the primal amplitude.
