Investigations carried out in connection with high-speed trains have revealed that an increase in speed does not necessarily result in a corresponding increase in the deformation and stresses in track components, which necessitates the use of a heavier track structure. The loads, deformations, and stresses in the track components were found to be augmented as a result of the incongruous movement of vehicles on the track including pitching, rolling, bouncing, etc., which occur when the track is poorly maintained. Therefore, it is possible to operate the same vehicles at a higher speed on a given track structure without imposing any additional loads and stresses, provided that the standards of maintenance of the track and the vehicles are
sufficiently improved so as to control these inhibiting movements of the vehicle when it runs at higher speeds. The existing track structure on the Rajdhani route is considered to be of adequate standard for speeds reaching as high as 120 to 140 km/h.
To achieve still higher speeds of the order of 160 to 200 km/h, the standard of maintenance needs to be very high, as very close track tolerances will have to be maintained. Maintaining the existing tracks at such tolerance limits may be uneconomical and may necessitate the adoption of an improved track structure, which can be maintained at closer tolerance limits at a comparatively low costs. The modern track structure, consisting of long welded rails with concrete sleepers, elastic fastenings, and ballastless tracks may well fulfil this requirement. The cost of this modern track may be comparatively high, but its maintenance will involve limited expenditure.