Using impulse response testing to examine ballast fouling of a railway trackbed

Abstract

The increase in freight and passenger rail travel has driven demand for more efficient and rapid investigation of railway trackbed ballast. One of the current approaches to evaluating the stiffness of railway ballast is to use a falling weight deflectometer (FWD). Whilst this is effective to establish overall track stiffness, it requires the rails to be unclipped from the sleepers – thus, it is very intrusive and expensive. The FWD technique does not measure ballast fouling.This paper focuses on using the impulse response (IR) testing method with a 12 lb instrumented hammer to excite a railway trackbed ballast composed of variously fouled ballast, with response measured using a geophone – in order to estimate ballast fouling.Finally, the impulse response results are successfully correlated with the assessed Fouling Index of the ballast.