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This is the final highway accident report (NTSB-HAR-71-1) from the National Transportation Safety Board, adopted in December 1970. It covers the collapse of the U.S. 35 bridge between Point Pleasant, West Virginia, and Kanauga, Ohio, on December 15, 1967, which killed 46 people. The Board found that the cause was a cleavage fracture in eyebar 330 at joint C13N. That fracture grew from a flaw produced over 40 years by stress corrosion and corrosion fatigue, in a spot that could not be seen or found by inspection.
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diagram which shows the status of the reassembly at the completion of this work, classifies all fractures in principal members of the stiffening trusses and eyebar chains, and shows the locations where laboratory specimens were removed. Further documentation of this work is covered in References 11 through 14, consisting of reports of examinations of fractures in the stiffening trusses, hangers, and towers. A few of the significant observations made in these reports as a result of this activity are as follows: a. All but one of the fragments of the various parts of the hanger connection at joint U13N were identified and examined. It was established that the failure of this connection initiated in the rivets which fastened the west diaphragm channel to the inboard gusset. On a basis of the field examination of the fragments, it appeared that the failure had occurred in two stages, the first being initiated while the hanger was in a nearly vertical position with respect to an east-west plane, but inclined with respect to the north-south plane. Final separation appeared to have occurred when the hanger was inclined at a considerable angle with respect to the joint in the east-west plane. This material was shipped to the laboratory for further examination. b. Cleavage fractures were found in the hangers in panel points 17 and 19 of the north truss, which are the two hangers just east of the Ohio tower in the upstream eyebar chain and truss system. Portions of both of these fractures were removed and shipped to the National Bureau of Standards for further examination. Similar fractures also were found in the hangers of the south truss of these same panel points, and in the hangers of both trusses just east of the West Virginia tower at panel points 45 and 47. c. Two cleavage fractures were found in the lower chord of the north stiffening truss between panel points 12 and 13. The extraction of samples from these fractures was not completed until January of 1970, when they were removed, and taken to NBS for examination. d. A detailed examination of deep scars and bruises on parts of the Ohio tower provided a highly consistent explanation of the sequence of events in the collapse of this tower and a possible explanation of why the saddle casting at the top of the south leg appeared to have been pulled away from the top of the tower leg along an axis parallel to the leg itself. Details of this sequence of events are covered in Reference 14, but may be summarized as follows: (1) Initially the top of the north leg of the tower moved eastward as a result of the separation of joint C13N in the Ohio side span.
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