(1) The failure of the Tay Bridge was due to a change in the original design. It was intended to construct the piers entirely of brick and concrete and fourteen out of fifty were made this way. However, during construction the river bed was found to be less strong than expected and so, to reduce the pressure on the river bed (and also to save cost), the designer, Sir Thomas Bouch, decided to build the piers of brick and concrete up to the high water mark and then construct the upper portions from cast iron pipes with cross-bracing. The brick and concrete piers still stand. Many of the original girders which went across the tops of the piers were re-used and are still in use today, but the cast iron pipes collapsed after six months (and did not turn out to be cheaper).