Estimation of rail irregularities

Inspection cars that have been used to measure rail irregularities are costly and need operators. In this paper, a method to estimate rail irregularities by measuring accelerations of a passenger car instead of direct measurement by using a conventional inspection car is proposed. Using a System Identification technique and data obtained by simulations based on a three-dimensional rail vehicle model with rail irregularities, the proposed method identifies an inverse system where inputs are accelerations of a vehicle and outputs are rail irregularities. The quality of the estimation is evaluated quantitatively by using the Mean Square Error. The effects due to two major uncertainties, mass variations and speed variations, are evaluated by using the Singular Value Decomposition in order to present the limitations of the estimation using a nominal model.