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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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operation. Gross pier displacement was also eliminated by the fact that the bearing surfaces of the pedestal seats for the tower legs were found to be level and in proper position. The possibility that small movements of the anchorages or piers could have resulted in misalignment of the towers or sagging of the main chains with consequent overstressing of vital parts was eliminated by the results of the precision survey conducted by Modjeski and Masters (Reference 5, Exhibit Number 4-0). This survey was conducted using a combination of direct chaining over land and direct Geodimeter (an electronic distance measuring device) over water. The latter measurements were checked by a triangulation technique using a Geodimeter measured base line on one shore and precisely measured angles. The results of the survey indicate that all bearings and pedestals were within a few hundredths of a foot of the intended position with one exception. It was found that the distance between the pedestal shoes on the West Virginia tower pier (pier No. 4) and the pier at the east end of the West Virginia side span were approximately 0.25 feet closer than the 370 feet shown on the drawings. It was noted, however, that the distance between the pedestals on the Ohio tower pier and the West Virginia tower pier checked within 0.02 feet of the plan dimension of 700 feet, and that the distance between the pier at the east end of the side span and the next pier eastward also checked very closely with the planned dimension. It was therefore concluded that the erector had chosen to correct a slight error in the original construction by taking advantage of the adjustment provided in the West Virginia side span by the toggle link at the West Virginia tower. With the completion of these surveys and their interpretation, all possibility of substructure failure was precluded. The computations performed by the Bridge Design Review and History Group (Reference 3 and Reference 5, Exhibit No.3-E) indicated that the original design had been executed in accordance with normal engineering practice in use at the time of the original design, and that it was without mistakes or significant errors in the original stress computations, although there was a minor error in the computed dead load stress in member L13-L15 of the Ohio side span and corresponding members of the center span and West Virginia side span.* That group also established the fact that the stresses in critical members of the eyebar chain and trusses produced by the loading on the structure at the time of collapse were well below the specified maximum stresses provided for in the original design. Computations were carried out by the American Bridge Division of U. S. Steel using a digital computer, and were independently checked by the firm of Modjeski and Masters. Both the original design computations and the check computations were computed on the following basis: a. The structure was assumed to be linear in its behavior. The full implications of this statement will be discussed in the analysis section of this report.
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