Impact-Load Reduction Effect of Under Sleeper Pads on Railway Tracks

This study quantitatively evaluated the reduction effects of sleepers equipped with ethylene propylene diene monomer (EPDM) under sleeper pads (USPs) on train impact loads and vibrations. For comparison, 6 mm-thick stiff pad, 5 mm-thick medium-stiff pad, and normal sleepers were installed on the Gyeongbu Line. For one year, the vertical displacement of the rails, wheel load, and track acceleration when the KTX trains passed were measured, and the results were compared and analyzed. The analysis confirmed the impact load reduction effect of the pad sleepers, as they generally decreased the dynamic amplification factor (DAF), wheel load, and ballast acceleration compared with the normal sleeper. Regarding the impact load reduction performance over time, the 6 mm-thick stiff pad maintained a consistent load reduction performance throughout the measurement period, whereas the 5 mm-thick medium-stiff pad exhibited relatively significant performance variations.