In situ impact testing of a light-rail ballasted track with tyre-derived aggregate subballast layer

In this study, the dynamic behaviour of ballasted track with and without tyre-derived aggregate (TDA) as subballast layer was assessed using impulse–response (IR) test. For this purpose, a prototype of a ballasted track was established and many IR tests were carried out. The obtained results were represented in three different kinds of velocity–time, velocity–distance and velocity–frequency curves. Processing of the obtained results revealed that TDA efficiency in terms of vibration reduction was in the range of 17–46 dB when the impact was applied to the ballast and it was in the ranges of 6–32 dB and 6–47 dB while impact locations were on the sleeper and rail, respectively. Overall, it was proven that TDA with the particle size of 5–50 mm and thickness of 200 mm reduced by 6–47 dB in vertical vibrations with the dominant frequency range of 32–63 Hz.