 A simple vertical crack with a freshly fractured surface and old rust marks on the face was easily distinguished to the side of the centre joint, extending from the bottom flange to the top of the girder.This was associated with a casting defect hidden behind a surface skin of sound metal at the thickest part of the section where the flanges met the web.This was described by the accident report as a large honeycomb, or drawhole, which measured 3½ ins (c 90 mm) across at the face, and narrowed to about 1½ ins (c 40 mm).