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.
“R.G.”1 page
Read from the scan by GLM-OCR; expect the odd misread word.
4. The growth of a small crack by the stress-corrosion mechanism had been known only in a few ferrous and non-ferrous metals of that era under severe exposure conditions, such as containers used in the chemical and food processing industry, riveted steam boilers, and machine parts subjected to various corrosive environments. The role of corrosive environments in accelerating the normal fatigue process was also seldom considered in normal outdoor environments. In the light of present day knowledge, the stress at the edge of the hole in the eyebars was too high for a material subject to crack growth by either of these mechanisms without special corrosion protection. (120) 5. There was a water collection pocket adjacent to a point of high stress, as there is in any eyebar construction, where there is sufficient clearance between the pin and the pinhole surface to permit entry of water. (95) 6. This point of high stress was not accessible for inspection. (7, 32, 46) 7. The use of only two eyebars per link in the eyebar chain. This made the total failure of the chain inevitable once the fracture occurred in eyebar No. 330. Had there been three or more eyebars per link, there would have been the possibility that the failure of one bar would not have led to disaster. (7) ## C. With Respect to the Implications for the Safety of Other Bridges: 1. The relatively rare combination of all the factors cited above for the Point Pleasant Bridge makes the recurrence of this exact type of failure remote. The only other bridge in this country to combine all these factors is at St. Marys, West Virginia, and it has been closed since early in this investigation. (2) 2. There are, however, many other structures which possess one or more of these factors as features in their designs. It is not precisely known what the critical combinations may be for the initiation and growth of similar hidden defects to critical size. (120) 3. The current vigorous efforts to upgrade the quality of bridge inspection will certainly detect those structures where surface corrosion, impact damage and other visible or measurable defects impair their strength. Nevertheless, the possibility of small flaws in critical elements made of material susceptible to stress-corrosion, corrosion-fatigue and other time dependent flaw growth phenomena does exist. In some cases these materials also have limited fracture toughness, so that the critical flaw size is undetectable by present inspection devices and methodology. (82, 83, 120) 4. An acceleration of the existing program of improvement of bridge safety is needed, and should include efforts to:
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.