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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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in hanger C19-U19 north contained no pre-existent crack and showed evidence of both bending and high strain rate. f. In the further pursuit of fractures in the structure which might have occurred prior to the fracture in eyebar No. 330, a careful examination was made of the cleavage fracture in lower chord member L12-L13 of the north truss (Reference 22). This was one of two such cleavage fractures within this panel length of the lower chord and occurred some six feet from the connection at panel point L12N. The fractures in the two channels composing the lower chord at this point both originated at rivet holes where lacing was attached to the member and were therefore staggered by approximately 8 inches. Metallurgical examinations showed that these fractures had originated in small pre-existent cracks at the edges of the rivet holes (See Figure 13a). The fracture surface showed clear evidence of a high rate of loading and of crack propagation, with branching or secondary cracks extending into the material below the plane of the fracture. Some unusual small reflective specks (See Figure 13b) were noted within the fracture surface of the south channel of the pair. Microprobe analyses indicated that these reflective specks contained both lead and calcium. Although there was speculation that a tightly closed crack may have existed in this area for some time prior to the collapse and that lead may have migrated there from lead oxides in the paint by virtue of the establishment of an electrolytic"cell," the metallurgical and fractographic examinations contradicted and disproved this speculation. They indicate that the entire fracture surface with the exception of a small area near the origin was formed during the application of a single load at a high loading rate. g. A further report discusses the investigations of the rivet failure in joint U13N (Reference 23). As mentioned above in the discussion of the field investigations, the hanger connection at this joint was pulled from the truss. This hanger connection is made up of a pair of channels with reinforcing plates attached, through which the pin at the lower end of the hanger passes, connected in turn to two other channels known as diaphragm channels which were riveted to the inboard and outboard gusset plates. Several of the rivets showed unusual fracture surfaces and were, therefore, examined metallurgically to determine the nature of these fractures. Figure 14 shows the fractures in the group of rivets which fastened this channel to the outboard or north gusset plate. The failure plane was at the interface between the channel flange and the gusset plate. Rivets A and B, which were the two lowest rivets in the joint show rather unusual fractures. The metallurgical examination indicates that the fractures originated in small discontinuities at the outside surface of the rivets in areas that exhibited significant decarburization. Fracture was by cleavage in these initial zones, but by mixture
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