It's possible that better railway track structures will some day be commonly made by the paving train. In Derbyshire, England a continuously reinforced strip of cast-in-place concrete has been laid as track base to provide support to rails at minimum cost. Essentially, the design of the track structure is: a beam (the rail) on an elastic foundation (the pad) resting on a beam (the concrete pavement) on an elastic foundation (the subbase). Although standard techniques were used, computer programs and analytical techniques had to be devised for analysis of the complete system in two dimensions. The dynamic effects of high-speed trains were studied, as were also the shrinkage and thermal stresses in the concrete and the hammering effects of wheel flats on freight cars.