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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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(3) The fracture of the lower limb of the C13 head of this eyebar was precipitated by the existence of a small semi-circular crack about 1/8-inch in radius and an auxiliary crack about 1/16-inch in radius (See Figure 7). Both of these small cracks originated on the inside surface of the pinhole near the south face of the bar and on a plane roughly through the center of the pin at right angles to the longitudinal axis of the eyebar. The remainder of this fracture showed two zones of fracture propagation, the first of which extended from the crack roots to about 0.6 inch from the pinhole surface. The fracture in this zone is cleavage without any evidence of branching or secondary cracking. Such secondary cracking becomes apparent in the second zone, which extends through the remainder of the fracture. (4) Cracks similar to that associated with the fracture were found on the inside surface of the pinhole approximately 1/16 inch from the plane of fracture and near the same face of the eyebar as those associated with the fracture. Further examination disclosed that there were additional cracks at distances up to about 1/2 inch from the fracture on the inboard piece of the eyebar (that which was still attached to the shank) and at about 0.1 inch from the fracture in the outboard piece which separated. Sectioning and examination of these cracks under high magnification indicate that they originated from small corrosion pits on the pinhole surface and penetrated radially into the eyebar material, approximately at right angles to the lines of principal stress. (5) The faces of both the pre-existent crack associated with the main fracture and the similar cracks in adjacent areas were covered with dark oxides of a distinctly different color and texture than the surface rusting which developed on the remainder of the fracture surface. b. Part 2 of the National Bureau of Standards report (Reference No. 18, "Metallurgical Examination and Mechanical Tests of Materials from the Pt. Pleasant, West Virginia Bridge," describes further metallurgical work on eyebar No. 330 and on eyebar No. 33, which was the south bar of the pair in the north chain, panel point C11-C13, and which contained the burr on the north edge of the pinhole surface of the C13 head of this bar. The important conclusions of this report are as follows:
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