Development of Tire Shred Underlayment to Reduce Groundborne Vibration from LRT Track

Groundborne vibration reduction for rapid transit tracks usually takes the form of some type of "soft" or "special" track fastener, or a type of isolation system built under or incorporated as part of the track structure. These mitigation measures are for the reduction of vibration annoyance. Due to the great abundance of scrap tires, which can be shredded, an investigation was undertaken to determine what vibration attenuation properties are characteristic of tire shreds and how tire shreds would attenuate groundborne vibration. Two sets of field tests were performed to determine the vibration attenuation and damping properties of tire shreds for potential use beneath rail lines and other possible applications. The first set of tests was without rail and included three mobile vibration sources and one stationary impact vibration source. The second set of tests was performed using a short test and control section where the shredded tires were installed under ballast and tie rail transit track. Overall, the use of shredded tires as an underlayment beneath ballast and tie track as a means for reducing groundborne vibration appears to be both practical and viable in addition to finding an additional use for scrap tires.