In situ performance of a ballasted railway track with under sleeper pads

An extensive full-scale field test to investigate the influence of under sleeper pads (USPs) on track quality (with respect to magnitudes of vertical track irregularities) and track dynamics has been conducted on the Schweizerische Bundesbahnen test site at Kiesen in Switzerland. Static track geometry data and dynamic track responses in terms of sleeper strain and accelerations of rail and sleeper during train pass-by have been measured and analysed. It is observed that the use of USPs generates higher rail and sleeper accelerations but lower sleeper strains due to bending. The degradation of track geometry appears to slow down when USPs are used.