In my knowledge of physics there is no way of preventing any material from expanding some way due to temperature variation. An American rail magazine reports that 40 degree (F) temperature change will result in 17 inches of expansion per mile - nearly one and a half foot. Inspite of concrete sleepers and the new clever fixation of steel rail, the only way I can see that his can be avoided is if the steel is especially designed to expand in width and depth and not in lenght. Can someone please help explain the exact physics? I have read so many explanations that do not make sense to me.