Vibration Generated by Underground Railway Trains

The control of vibration generated by railways in tunnels is complicated by the dynamic interaction between tunnel and track. Conventional methods (floating slab track, ballast mats, under-sleeper pads) do not perform as well as might be expected and it is the purpose of this paper to explore the sources of error. The major factors which must be taken into account pertain to the three-dimensional vibration modes of the tunnel and their interaction with the track and with the surrounding soil. These factors are usually omitted under existing design methodologies and supposed improvements in track design are often not effective. The model used to quantify tunnel effects is based on exact solutions to the 3-dimensional wave equation as applied to a tunnel of infinite length. For a typical tunnel there are many resonance frequencies to be found in the range from 5 to 100Hz, most significant for railway vibration calculations.