Measurement of long wavelength irregularities on rails

Abstract

Measurements are presented of irregularities on rails in the wavelength range 6.3-5000 mm. Two types of equipment have been used, a hand-held measuring trolley (the so-called CAT) and vehicle-mounted RCA equipment that is typically used for routine quality assurance of rail reprofiling work. There is close correlation of one-third octave spectra from the two types of equipment for most of the wavelength range of interest. The RCA is a more repeatable instrument than the CAT for wavelengths of greater than a metre. Use of such equipment offers a relatively simple, readily available means of controlling residual irregularities from reprofiling and thereby reducing noise. Control of irregularities over a wide wavelength range is within the capabilities of modern reprofiling equipment, but only if an appropriate specification is rigorously monitored.