TRACK SUPPORT MUST BE RIGHT IF CONCRETE SLEEPERS ARE TO SURVIVE

Wheel flats are the most important source of dynamic forces affecting North American track, and concrete sleepers are more vulnerable to consequential damage than wood. Recently a much deeper understanding of the interaction between track forces and the behaviour of the track support has been achieved. It is now possible to specify ballast and subgrade conditions that will allow heavy haul trains with 30 tonne axles to operate economically over concrete-sleepered track, but provision of wheel-flat detectors may still be desirable.