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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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i. Supplemental dredging operations after the completion of the main salvage operations had been successful in locating the outboard piece from the fractured eye of eyebar No. 330, but they had not located the pin from joint C13N in spite of three separate searches. j. The wreckage on the Ohio shore had been carefully disassembled to obtain additional photographic coverage and to permit examination of freshly exposed pins and pinholes in the eyebar chain. The latter inspections were conducted in part to look for evidence of fretting fatigue. k. An experimental program had been conducted on the bridge at St. Marys, West Virginia, which was a near duplicate of the Point Pleasant Bridge, to confirm computed vibrational frequencies and mode shapes, to assess the dynamic effects in eyebars and hangers produced by a single heavy vehicle moving across the structure, and to make strain measurements of certain localized secondary stresses on the chain bent post, gusset plate U7N, and in the eyebar heads. ## 2. Laboratory Work Reported in Interim Report (Reference 2) Laboratory work had been initiated at the National Bureau of Standards in order to examine the fracture in eyebar No. 330, the burr and deformation of eyebar No. 33, and the fractures in the chain bent post, gusset plate U7N, and several selected fractures from the lower chord members recovered from the wreckage on the Ohio shore. The Battelle Memorial Institute, Columbus, Ohio, had begun some basic work on the materials used in the eyebars, the hangers and the trusses to determine their susceptibility to brittle fracture due to the presence of small flaws. Studies to determine the fretting fatigue susceptibility of the eyebar material had been initiated at Ohio State University. Additional metallurgical examinations were planned at the National Bureau of Standards and the laboratories of the U. S. Steel Corporation had agreed to perform parallel investigations. The examination of the brittle fracture in eyebar No. 330 at the National Bureau of Standards had revealed that there was a small radial crack about 1/8-inch deep extending from the eyebar hole surface in the plane of the fracture. The origin of this crack was at a point which was in contact with the pin in the assembled structure. Examination of the hole surface adjacent to the fracture indicated that there were additional smaller cracks of a similar nature generally parallel to the one which had precipitated the fracture. Representatives of the Battelle Memorial Institute were asked to examine a number of eyebar heads at the reassembly site and on the Ohio shore to determine whether or not such cracks were present in other eyebars of this structure. None of the laboratory work had progressed far enough at the time of the interim report to result in conclusive reports.
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