Under ballast mat – A review of recent developments, limitations, and future prospects

A high frequency of loadings and an excessive amount of axle loads are rising as trains are becoming faster and heavier. In this regard, improvements in track design, such as using an under ballast mat, are vital to performance improvement. In addition to reducing noise, vibration, and ballast degradation, UBMs are designed to improve the dynamic behavior of tracks, thus extending their service life and increasing safety. This paper provides an overview of the recent developments on UBMs, identifies the crucial characteristics of different kinds of mats, including fatigue strength, environmental conditions, stiffness, and ballast deformation, and describes challenges for more widespread adoption. Limitations of using a UBM include their high cost and stiffness, limited knowledge of long-term efficiency, and interlocking reliability. This paper also provides future perspectives and prospects for overcoming the challenges in the utilization and acceptance of UBMs.