Vibration Mitigation: Under-Ballast Mats in Heavy-Haul Applications

AbstractLocomotives and trains—as well as the tracks on which they run—emit noise and vibrations. Vibrations are transmitted through the subsurface to the nearby building, where they can be felt directly or are heard as secondary airborne noise. Recurring vibrations can impact the health of people living and working in the nearby areas. This article describes the application of under-ballast mats (UBM), an elastic spring installed under the railway ballast, as an effective measure for vibration mitigation. The particular novelty is the use of UBMs for vibration mitigation with heavy-haul trains, which have high axle loads of about 33 t. This article firstly presents the process of assessing the specific conditions of the customers site in Mexico. Secondly, it looks at the steps in choosing a suitable UBM and performing design calculations. Finally, the vibration measurements are discussed to assess the performance after UBM installation. The measurements show a vibration reduction of 15.5 dB at 63 Hz and 19.9 dB at 125 Hz. The perceptible vibration peaks inside the building were reduced by 44%. The result confirms the suitability of UBM for vibration mitigation on heavy-haul lines and thereby reducing the impact of vibrations on people’s health. This consequently fosters acceptance among railroad operators and developers.