Identification of the railway track vertical offset and cross-level irregularities using axle-box accelerations on commercial trains

Railway geometry monitoring is essential for track maintenance. Recent developments have led to the use of accelerometers mounted on the axle-boxes of commercial trains to measure vertical rail irregularities. The aim of the work presented hereunder is twofold. First, the uncertainties involved in estimating the vertical offset and cross-level of railway tracks by double integration of accelerations measured in axle-boxes are quantified and discussed using simulation. This first part of the work is carried out with the help of railway dynamics simulation, which enables the environmental conditions, system inputs, and train reaction to be perfectly controlled. Particular attention is paid to understanding the displacements and rotations of the sensors placed in the axle-boxes. Second, based on these elements, an enhanced reconstruction that is more accurate, particularly for long wavelengths, is proposed. Finally, an application to measured signals is presented.