One Tiny Change, Approved by Phone, Killed 114 People

On July 17, 1981, two packed walkways collapsed onto a tea dance in the lobby of the Hyatt Regency hotel in Kansas City, killing 114 people. The cause was one small design change, approved over the phone, that nobody ever checked. This is the story of the Hyatt Regency walkway collapse. The hotel opened in July 1980 after a fast-tracked build, with suspended steel, concrete and glass walkways crossing its atrium. The original design hung the 2nd- and 4th-floor walkways from one set of long rods, and even that met only about 60% of the Kansas City building code. The steel fabricator proposed two shorter, offset rods instead, which hung the 2nd-floor walkway from the 4th-floor beams and doubled the load on those connections. On the night, the box beams split along their welds and the nuts pulled through. Investigators for the National Bureau of Standards found the walkways would have failed under about a third of the load they carried. 114 people died and 216 were injured. The engineers of record were found guilty of gross negligence, misconduct and unprofessional conduct by the Missouri licensing board and lost their licences, but no one was convicted of a crime. The Kansas City Star won a Pulitzer Prize for its coverage, and engineers today are held responsible for reviewing fabricators' shop drawings. Sources: "Hyatt Regency walkway collapse", Wikipedia: https://en.wikipedia.org/wiki/Hyatt_R... National Bureau of Standards, "Investigation of the Kansas City Hyatt Regency Walkways Collapse" (NBS BSS 143, 1982) The Kansas City Star / Kansas City Times investigative coverage (Pulitzer Prize, 1982) Henry Petroski, "To Engineer Is Human" (1985); M. Levy & M. Salvadori, "Why Buildings Fall Down" (1992) Some details (how the change was communicated and who approved it) were disputed in the hearings; we follow the investigators' findings. Photos via Wikimedia Commons: Kansas City, MO skyline at night (Lasse Fuss, CC BY-SA 3.0); Figure 5.4 - NARA - 70172329 (Unknown authorUnknown author o, Public domain); Hyatt Kansas City Collapse (Dr. Lee Lowery, Jr., P.E., Public domain); Hyatt Regency Crown Center Kansas City MO (user:Charvex, Public domain); Crown Center 3 Kansas City MO (User:Charvex, Public domain); Kansas City MO Skyline 14July2008 (User:Charvex, Public domain); Kansas City Hyatt Regency Walkways Collapse 1 (Dr. Lee Lowery, Jr., P.E., Public domain); Figure 5.30 a - NARA - 70172364 (Unknown authorUnknown author o, Public domain); Hyatt Regency collapse floor view (Dr. Lee Lowery, Jr., P.E., Public domain); Hyatt Regency collapse end view (Dr. Lee Lowery, Jr., P.E., Public domain); Figure 5.6 - NARA - 70172359 (Unknown authorUnknown author o, Public domain); Hyatt Regency collapse support (Dr. Lee Lowery, Jr., P.E., Public domain); Figure 5.7 - NARA - 70172360 (Unknown authorUnknown author o, Public domain); Kansas City Star Building (32806858677) (Tony Webster from Minneapolis,, CC BY 2.0); SheratonCrownCenter (Hello2020121212, CC BY-SA 4.0). Music: "Heart of Nowhere" and "Rising Tide" by Kevin MacLeod (incompetech.com), licensed under Creative Commons: By Attribution 4.0 License, http://creativecommons.org/licenses/b... Some scenes are AI-generated for illustration (marked "AI RECONSTRUCTION" on screen; no photos exist of those moments). Diagrams are simplified. More from us: Backfire Docs (plans that backfired):    / @backfiredocs   Cockpit Docs (aviation incidents):    / @cockpitdocs   Root Cause Docs (history behind today's conflicts):    / @rootcause_docs   #Engineering #History #Disaster