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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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(2) The bracing connecting the two tower legs pulled the top of the south leg in a northeasterly direction to conform to the movement of the north leg. After perhaps two feet of eastward motion of the top of the north leg, the eccentricity of the vertical load imposed on the south leg by the still intact south eyebar chain produced severe bending stresses in the south leg as indicated by the fact that there is a permanent bend in this leg above Strut PS1 (See Figure 35). Further bending resulted in failures in the tower bracing system and a fracture through the south leg about 69 feet below the top of the tower. This portion of the tower leg continued to tilt northward falling with considerable velocity because it was still carrying the south eyebar chain. This tilt dragged all portions of the south stiffening truss attached to the eyebar chain toward the north. (3) This northward leaning of the upper 69 feet of the south leg continued until it made contact with the west side of the north leg of the tower which was falling to the east. At about this time fractures apparently occurred in the south eyebar chain in the main span. (4) The next contact of the upper portion of the south leg occurred when a point about 26 feet below the saddle casting struck the southwest corner of the north leg about six feet above the top of the girder G1 (See Figure 35). As is evidenced by heavy gashes in the north leg at this location and corresponding marks on the south leg, this violent collision resulted in a complete cleavage fracture in the south leg about 26 feet below the saddle casting. The partially inverted position of the portion of the south leg to which the saddle casting was attached and the violence of the collision were apparently responsible for the manner in which the saddle separated from the top connection angles of the south leg. e. The presence of numerous cleavage fractures in the lower chord of both stiffening trusses in the center of the main span was noted, indicating that some specific cause existed for these fractures.
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