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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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Surface Number of Pits Average Pit Depth,in. Maximum Pit Depth,in.
Two inch wide strip,pinhole to outside edge,south face
Half inch nearest hole 31 0.014 0.038
Remainder of surfaces 7 0.008 0.013
Two inch wide strip,pinhole to outside edge,north face
Five inches nearest hole 60 0.027 0.053
Outer four inches 42 0.049 0.105
Pinhole surface(normally in contact with the pin)
First 6/16"from north face 4 0.0045 0.006
Next 9/16"from north face 27 0.005 0.007
Next 10/16"from north face 51 0.006 0.008
Remaining 6/16"to south face 23 0.0075 0.012
d. Reference 25, "Examination of Point Pleasant Bridge Eyebars," dated May 18, 1970, reports the studies conducted by U. S. Steel as a part of the work of the special task group appointed to investigate the mechanism by which the crack in eyebar No. 330 grew to critical size. The specimen was taken from eyebar C9-C11 north chain, south bar, which contained a tight crack similar to the pre-existent crack in eyebar No. 330. As noted in the discussion of the work by the Battelle group, this specimen was broken open by a static load to extend the crack at the USS laboratory. The general appearance of the piece retained by USS for examination is shown in Figure 24a. Four distinct regions were noted in the fracture surface, designated A, B, C, and D in Figure 24b. When first examined, the black oxides in region A were noted to be wet with water. An attempt was made to measure the pH, but there was not sufficient water for a valid reading. Within five minutes, the surface was dry. This region marks the limits of the crack originally in the piece.
Zones B, C, and D were formed when the specimen was loaded to failure. Zones B and C were both gray in color, but zone D was light in color, and a zone of definite fast fracture.
In addition to examination of all regions by fractography using the scanning electron microscope, the material present in zone A was checked for the presence of certain elements with the x-ray spectroscopy attachment, by electron probe analysis, and by x-ray diffraction techniques. The black oxides were identified as iron oxides $ \left( \mathrm{F e}_{3} \mathrm{O}_{4} \right. $ and possibly $ \mathrm{F e}_{2} \mathrm{O}_{3} $), and other particles in this region contained calcium, silicon, chlorine, aluminum, and sulfur. The calcium and silicon were frequently associated, and most sulfur indications were associated with manganese, indicating that these particles may have been manganese sulfide from the underlying steel. An azide test for detection of sulfide was conducted on zones A and D. Both zone A and zone D gave moderate indications, with that in zone A being somewhat 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.