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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.
“Cooper”1 page
The south chain bent post of the Ohio side span must have completed its plastic bending failure to the north at about this same time, since it struck the deck before the deck slab fell away. (Reference 35, installment 1, p. 21). Joint L13N had fallen about ten or twelve feet at this time, and joint U13N had followed this vertical motion but had also moved three or four feet northward due to the rotation of the deck at this point. As the top of the north leg of the Ohio tower continues to move eastward, the linkage formed by the hanger U13N-C13N, pin C13N and eyebars C13N-C15N pulled into a straight line, wrenching hanger connection U13N from the truss. The direction of pull, relative to the original position of the truss, was eastward and slightly to the south of the vertical. The portions of the deck between panel points L9 and L11 had now fallen about 16 feet at its northerly edge. The resulting counterclockwise rotation of the deck, viewed from the west, was accelerated by the northerly movement of the south chain. The portion of the deck from about L6 to L10 dropped enough so that what had been the northerly end of the floor beams made contact with the ground. The shock of this ground contact probably fractured the connections of the floor beams to the south truss, allowing the south ends to drop to the ground, each floor beam rotating about its ground contact point. This resulted in this portion of the floor system coming to rest considerably south of its original position. The portion of the Ohi-side span floor system between L3 and L5 apparently sagged to the ground with but little counterclockwise rotation viewed from the west. It was, however, thrown to the north as a result of its attachment to the south chain during the initial part of its fall. Joints L1, L2 and L3 were thrown even farther north, apparently because of the pivoting of L0-L1 at the pier. In the main span, the south truss between the Ohio tower and panel point 21 broke loose from the chain by fractures in the hangers, permitting the south side of the deck to follow the north side in this portion with only slight counterclockwise rotation viewed from the west. The center portion of the south truss in the main span apparently remained attached to the chain during this phase of the collapse and produced further counterclockwise rotation in the deck. ## Step 6 Time = 4.0 seconds The collapse of the Ohio side span was virtually complete. During step 6, the upper portion of the south leg of the Ohio tower continued to rotate to the north, dragging the south chain and the portions of the trusses still attached farther to the north. The north chain,
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