Actual states of wheel/rail contact forces and friction on sharp curves – Continuous monitoring from in-service trains and numerical simulations

•We developed a new measurement method that can continuously measure the contact forces.•The method can grasp rail/wheel interface conditions every time using service trains.•We are collecting huge data on commercial lines by the developed method.•We analyzed the mechanism of increase of L/V (i.e. Y/Q) in sharp curves.•Increases of L/V by friction change and track irregularities are verified.

The authors researched and developed a new measurement method that can continuously measure the contact forces and derailment coefficients at all curves of commercial lines. This new method can determine the derailment coefficients, which change according to the friction coefficients and other factors, using the measuring system on in-service trains. In this paper, the analysis results for actual curve data collected on commercial subway lines are introduced. Additionally, parameters that are influential on the changes of the derailment coefficients, such as “friction” and “track irregularity,” are discussed using the regression analysis on the accumulated data with the newly developed system.