The viaduct had become fragile largely because of crumbling of much of its stone, which was not of the best quality, being of a minutely fissured weak texture. With lack of maintenance, vegetation and weather effects this weakness had led to widespread stone loss and serious undercutting to all piers at or near water level. The west pier was seriously cracked, mainly around its traditional hearting, and had lost about a third of its 2.9 m thickness. Some movement had occurred long ago causing stretching and hogging of the arches adjoining the west pier. ... The north spandrel wall had suffered extensive stone loss at the top and some peeling away of pier bull-noses.