I was interested in your debate on track bed technology (NCE 26 April). Neither of the contributors mentioned the main problem in relation to rigid versus flexible track bed design, which is the infrastructure support under the track.
In the UK much of the infrastructure supporting the track was designed with a moderate safety factor by the Victorians to save significant costs on landtake and embankment structures. In consequence, many tracks are regularly re-ballasted to correct long term continuous settlements and ground movements.
Therefore, rigid track would require improvements to the infrastructure support at significant cost possibly with extra landtake to reduce embankment movements and increase factors of safety.
Richard Williams, chief executive, Owen Williams Group RichardWilliams@Owen williams. co. uk