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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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to the center of the main span, the only possibility of a collision with a part of the structure which could have precipitated the collapse would have been in this area. Had a collision occurred due to a vehicle in the eastbound lane the damage would have been to the south stiffening truss. This would have most likely produced a failure in the south eyebar chain if any point in the main suspension system were vulnerable to shocks. As discussed above, it is known on the basis of physical evidence that the initial break occurred somewhere within the Ohio side span and it has been confirmed that the eyebar chain associated with the south stiffening truss was intact from the Ohio anchorage to the top of the Ohio tower. Further search for evidence due to this cause was therefore abandoned. There were rumors in the Point Pleasant area that a sonic boom had occurred just prior to the collapse of the structure. A check with nearby military installations indicated that no aircraft likely to produce such effects were operating in the vicinity of the Point Pleasant Bridge at that time, and there were no other complaints of even minor damage in this area. Those witnesses that were either on the structure or nearby at the time of collapse testified that they heard a loud noise, or a series of loud noises, just prior to the collapse which some described "like a sonic boom." The chains of this bridge were designed to carry a live load of 1400 pounds/foot applied at the deck level, which is approximately 50 pounds/square foot on the deck. This is a heavier unit loading than that for which most roof structures are designed and it seems improbable that such an overpressure could have been exerted on the deck of the structure without having caused extensive damage to houses and other buildings in the Point Pleasant area. Further pursuit of this possible cause for the collapse was, therefore, abandoned.
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