Improving wheel load estimation performance of PQ monitoring bogie using lateral force measurements

Monitoring wheel-rail contact forces is essential for ensuring railway operational safety. The derailment coefficient, defined as the ratio of lateral force to wheel load, is a critical parameter for assessing the risk of flange climb derailment. The PQ monitoring bogie has been developed to monitor this coefficient, with wheel load estimation currently based on the vertical displacement of the primary suspension. However, this method does not account for factors such as lateral forces on the wheelset and the dynamic geometrical relationship between the wheelset and wheel-rail contact points, leading to estimation inaccuracies. These inaccuracies are particularly pronounced on sharp curves due to stronger lateral force effects. This study proposes an enhanced method for wheel load estimation in PQ monitoring bogies by utilizing the bogie’s measurement capabilities. The proposed method is formulated by solving the quasi-static equation of equilibrium on curved track sections, incorporating the effects of lateral forces and dynamic variations in the lateral distance between the wheelset and the wheel-rail contact points. Since some input variables required for the proposed method cannot be directly measured, estimation techniques using lookup tables referenced by the train’s position along the track are also introduced. The accuracy of both the conventional and proposed methods is evaluated through multi-body dynamics simulations and on-track testing. Overall, simulation and test results demonstrate that the proposed method significantly improves wheel load estimation accuracy, especially on sharp curves, compared to the conventional approach.