Examination of the fractured eyebar which caused the collapse of the bridge led to the conclusion that a stress-corrosion crack had penetrated to a depth of ⅛ in. during the 40 years that the bridge was in service. This flaw was sufficient to initiate fracture across the remainder of the 16 in.² area of the lower limb of the eye due to the high local stress and the low fracture toughness of the steel.