In-situ measurements of synthetic sleepers and sleepers with under sleeper pads: effects on track structure and low-frequency ground vibration in soft soil

Abstract

Rail transport generates low-frequency vibration in soft soil. Low-frequency vibration can cause nuisance and damage buildings close to the track. A study was conducted to test the effect of composite sleepers and sleepers with under sleeper pads (USP-sleepers) on low-frequency vibration. Test track of several kilometres was built in western Finland with three different widths of FFU-sleepers, (Fibre-reinforced Foamed Urethane sleepers) five different USP types and reference concrete sleeper sections. Tested wagons had three-piece bogies, which have larger unsprung mass than typical Finnish wagons. The measured characteristics included soil vibration beside the track, rail deflection, embankment deflection at three depths and soil pressure in embankment at two depths. The study aimed to find out if and how the FFU-sleepers or USPs reduce low frequency vibration. The conclusion was that FFU-sleepers do not reduce low frequency vibration significantly but can amplify high frequency vibration. The USPs do reduce the vibration, but the specific mechanism behind this effect was not clearly seen in deflection or earth pressure data.