Documents / Document
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.
Read from the scan by GLM-OCR; expect the odd misread word.
3. Observed Facts and Witness Testimony Inadequately Explained at the Time of Interim Report There was already general agreement among the members of the investigation group that the fracture in eyebar No. 330 was the critical event in the collapse of the structure. It was not clear, however, whether this fracture resulted from the static load which existed at this joint up to the time of the collapse, or resulted from dynamic overload produced by vibration, vehicle effects, or a shock wave produced by a prior fracture somewhere else in the structure. An important part of the subsequent investigations, therefore, consisted of a thorough examination of all fractures in the wreckage in the general vicinity of the Ohio tower, to ascertain if those fractures might have produced such a shock. There were also questions as to whether the steel in the particular eyebar which fractured was typical of the steel in other eyebars in the structure and whether it met the contract specifications. With respect to the pre-existing* crack, two major questions were unresolved; namely, (1) was this crack sufficiently large to have caused the brittle fracture at the normal stress level expected at this location, and if so, (2) what was the mechanism by which this defect grew to critical size? Another major unresolved question concerned the order of events in the separation of joint C13N. Was it possible, assuming that the pin retainer cap was missing, that eyebar No. 33 "walked" off the end of the pin prior to the fracture of eyebar No. 330 due to the fluctuating load in the eyebar chain? Such an event would have produced a 100 percent increase of the load on eyebar No. 330. Or did the fracture in eyebar No. 330 come first, with subsequent misalignment causing eyebar No. 33 to slip off the pin? It was in the hope of resolving this question that much effort was expended in attempts to find the missing pin from this joint. There were a number of questions for which there were no clear answers at the time: a. If the failure occurred because of weakness or defects in the vicinity of panel point 13, how did the two heavily loaded dump trucks which were in the east bound lane successfully pass this point and reach the center of the main span before collapse occurred? b. What unusual event accounts for the fact that the saddle casting at the top of the south leg of the Ohio tower appeared to have been pulled vertically upward from its attachments, and how did this leg of the Ohio tower develop two fractures in the length above the portal bracing? *Pre-existing in the sense that it was present prior to the initiation of collapse, but not necessarily present when the bridge was erected.
Document, cited by the archive. The PDF is mirrored here; the original link is above. The text was read from the page images by GLM-OCR; expect the odd misread word. 202 pages are in the text index: search them above, or from the library's search.