Sir - The article 'Alliances deliver on performance and cost' (RG 6.04 p353) regarding the maintenance of standard gauge trunk lines in Australia mentions five critical elements of the track structure which must be harmonised to ensure predictable behaviour of the track.

It is stated that the ballast 'must not hold water and must be deep enough to spread the load to the formation'. But it is not mentioned that the ballast of a modern track with long rails or continuous welded rail must give the trackwork sufficient resistance in the lateral direction.

Therefore, the shoulders of the ballast profile should extend about 0·4 m from the ends of the sleepers. This is necessary to prevent sideways deformation of the track during warm days when the rails reach high temperatures. Even in the figure on p354 the ballast shoulders have been forgotten; the figure shows a track which will cause a lot of problems.

J J H Meulman

Amstelveen

Netherlands