On the filtering effects of the chord offset method for monitoring track geometry

A recently published paper in the literature used a particular method to establish the correspondence between the vertical accelerations registered in the axlebox of a wheel and the rail vertical profile which caused them as a way of monitoring the track conditions. However, that work did not consider the filtering effects due to the asymmetric chord approach that underpined the process. As a result of this, it is suggested that such method may produce some errors in the measurements at certain frequencies. The present work shows how the technique can be amended in order to maintain its quality.