Wayside measurement of lateral and vertical wheel-rail forces for rolling stock homologation

International safety standards have set criteria to decrease the chances of railway vehicle derailment. The proneness of low-speed wheel flange climbing can be assessed in several ways; one of them includes a combination of measurements done on a twist test rig and on a track; the latter consisting of measuring lateral and vertical forces on a flat (non-canted) test track made of a 150 m curve radius without transition run, under high adhesion conditions. This paper describes an advanced measuring system based on ER strain gauges mounted on the rails capable to measure both the aforementioned forces and to provide an estimation of the wheel/rail contact points for a wheelset. This novel feature takes into account lateral/vertical cross effects due to the actual contact point location allowing unprecedented accuracy and repeatability of these kind of measurements, that are not to be confused with existing weighing in motion (WIM) classical measurements. Existing literature, FEM simulations, design of the calibration devices, calibration phase, tests on the measuring system and its delivery are described. Amongst the trains used to validate the functionality of the bench were an ultra-high speed train, a flat freight wagon, a locomotive and an EMU trainset, all with satisfactory results.