Identification of Railway Ballasted Track Systems from Dynamic Responses of In-Service Trains

Railway track is one of the most important parts of the railway system, and monitoring its condition is essential to ensure the safety of trains and reduce maintenance cost. An adaptive regularization approach is adopted in this paper to identify the parameters of a railway ballasted track system (substructure) from dynamic measurements on in-service vehicles. The vehicle-track interaction system is modeled as a discrete spring-mass model on a Winkler elastic foundation. Damage is defined as the stiffness reduction of the track due to foundation settlement, loosening in the rail fastener, and lack of compaction of the ballast. Accelerometers are installed on the underframe of the train to capture the dynamic responses from which the interaction forces between the vehicle and the railway track are determined. The damage of the railway track can be detected via changes in the interaction force. Numerical results show that the proposed approach can identify all stiffness parameters successfully at a low moving speed and at a high sampling rate when measurement noise is involved.