In ballasted railway track, the deterioration of a sleeper and ballast support usually occurs due to both regular and irregular wheel/rail interactions. The repeated impact of train wheels over sleepers can reduce the lifetime of a sleeper and degrade ballast. To attenuate the effect of the impact loads on concrete sleepers, the resilient rail seat pads are used. After a certain time in service conditions, the worn rail pads have to be replaced. Assessment of the condition of rail pads is of great importance to track engineers and plays an important role in the overall track maintenance cost. A non-destructive methodology for evaluating and monitoring the dynamic properties of the rail pads has been developed based on an instrumented hammer impact technique and an equivalent single degree-of-freedom system approximation. In this study, the sample rail pads were collected during track maintenance work on a rail network in New South Wales, Australia. The measurements were performed using an instrumented hammer in a frequency range between 0 and 1,000 Hz. The effective mass, dynamic stiffness, and dynamic damping ratio were extracted in order to assess the current condition of the worn rail pads, thus assisting track engineers to optimise track maintenance operations.