Vintage: Hyatt Regency walkway collapse in 1981 killed 114, injuring 216, in Kansas City, Missouri, US
On 17 July 1981, two walkways collapsed at the Hyatt Regency Kansas City hotel in Kansas City, Missouri in the US, one directly above the other. They crashed onto a tea dance being held in the hotel's lobby, killing 114 and injuring 216. As a product of a corporate culture of profound neglect, the disaster contributed many lessons to the study of engineering ethics and errors and to emergency management. The event remains the deadliest non‑deliberate structural failure in American history and it was the deadliest structural collapse in the US until the collapse of the World Trade Centre towers 20 years later. This disaster is a case study teaching first responders the ‘all-hazards approach’ to multiple disciplines across jurisdictions and teaching university engineering ethics classes how the smallest personal responsibility can impact the biggest projects with the worst possible results.
Approximately 1 600 people gathered in the atrium for a tea dance on the evening of 17 July 1981. The second-level walkway held approximately 40 people at approximately 19h05, with more on the third and an additional 16 to 20 on the fourth. The fourth-floor bridge was suspended directly over the second-floor bridge, with the third-floor walkway offset several yards from the others. Guests heard popping noises moments before the fourth-floor walkway dropped several inches, paused and then fell completely onto the second-floor walkway. Both walkways then fell to the lobby floor. Disembodied limbs sprouted from the wreckage; bodies lie in halves; necks snapped. Some skin had already turned blue. “It all looked like a human sandwich, arms and legs hanging out”, said an eye witness.
Periodically, the triage supervisor, Dr Joseph Waeckerle, whistled for workers to be silent so he could locate more cries for help. Rescue workers hooked up IVs and administered pain medication. They determined one man pinned down by a steel beam would not survive without amputation; when he finally gave in, doctors took a chainsaw to his leg. He later died.
Construction crews hurried in bulldozers. However, with so many people still trapped, the machines were useless. Instead they called for cranes, forklifts and concrete-cutting saws. Overhead, a third walkway still hung from the ceiling. It was cracked.
A triage centre was erected in a hallway. The parking structure became a temporary morgue.
After nine-and-a-half hours, Mark Williams was the last survivor pulled from the wreckage. Exhausted rescuers nearly drilled him with a jackhammer trying to break apart the slab that pinned him down.
After 12 hours, the workers thought they had cleared most of the bodies. But at 07h15am Saturday morning, they lifted the final slab. Beneath it, 31 more people lay crushed to death.
The rescue operation
The rescue operation lasted 14 hours, directed by Kansas City emergency medical director Joseph Waeckerle. The team included members from the fire brigade, EMS units and doctors from five local hospitals. What they found was a 60-ton pile of steel, concrete and glass encased the victims. The hotel's forklift trucks and fire department's powerful jacks were unable to move the debris alone. Local companies were asked to help. Many responded and volunteered manpower as well as hydraulic jacks, acetylene torches, jackhammers, concrete saws, compressors and generators to aid the rescue operations. They also brought cranes and forced the booms through the lobby windows to lift debris. Deputy Fire Chief Arnett Williams recalled this immediate outpouring from the industrial community, “They said 'take what you want'. I don't know if all those people got their equipment back. But no one has ever asked for an accounting and no one has ever submitted a bill.”
The dead were taken to a ground floor exhibition area as a makeshift morgue and the hotel's driveway and front lawn were used as a triage area. Those who could walk were instructed to leave the hotel to simplify the rescue effort, and morphine was given to those who were mortally injured. Rescuers often had to dismember bodies to reach survivors among the wreckage. A surgeon had to amputate one victim's crushed leg with a chainsaw. Blood centres quickly received line-ups of hundreds of donors.
Water flooded the lobby from the hotel's ruptured sprinkler system and put trapped survivors at risk of drowning. The final rescued victim, Mark Williams, spent more than nine hours pinned underneath the lower skywalk with both legs dislocated and having nearly drowned before the water was shut off. Visibility was poor because of dust and because the power had been cut to prevent fires. A total of 29 people were rescued from the rubble.
Williams spent two months in the hospital. His leg turned black and became so swollen than doctors made incisions to relieve the pressure. After his kidneys shut down, he went on dialysis. Through it, he performed physical therapy and eventually graduated to a wheelchair, then crutches, then a cane. Feeling returned to his leg and he began to walk independently, though with a limp.
The Kansas City Star hired architectural engineer Wayne G Lischka to investigate the collapse, and he discovered a significant change to the original design of the walkways. Within days, a laboratory at Lehigh University began testing box beams on behalf of the steel fabrication source. The Missouri licensing board, the state Attorney General and Jackson County would investigate the collapse over the following years. An investigator for the National Bureau of Standards (NBS) characterised the neglectful corporate culture surrounding the entire Hyatt construction project as "everyone wanting to walk away from responsibility". The NBS's final report cited structural overload resulting from design flaws where "The walkways had only minimal capacity to resist their own weight".
Investigators found that the collapse was the result of changes to the design of the walkway's steel tie rods. The two walkways were suspended from a set of 1,25-inch-diameter (32 mm) steel tie rods, with the second-floor walkway hanging directly under the fourth-floor walkway. The fourth-floor walkway platform was supported on three cross-beams suspended by steel rods retained by nuts. The cross-beams were box girders made from C-channel strips welded together lengthwise, with a hollow space between them. The original design by Jack D Gillum and Associates specified three pairs of rods running from the second-floor walkway to the ceiling, passing through the beams of the fourth-floor walkway, with a nut at the middle of each tie rod tightened up to the bottom of the fourth-floor walkway, and a nut at the bottom of each tie rod tightened up to the bottom of the second-floor walkway. Even this original design supported only 60 percent of the minimum load required by Kansas City building codes.
Havens Steel Company had manufactured the rods, and they objected that the whole rod below the fourth floor would have to be threaded in order to screw on the nuts to hold the fourth-floor walkway in place. These threads would be subject to damage as the fourth-floor structure was hoisted into place. Havens Steel, therefore, proposed that two separate and offset sets of rods be used; the first set suspending the fourth-floor walkway from the ceiling and the second set suspending the second-floor walkway from the fourth-floor walkway.
This design change would prove to be fatal. In the original design, the beams of the fourth-floor walkway had to support only the weight of the fourth-floor walkway, with the weight of the second-floor walkway supported completely by the rods. In the revised design, however, the fourth-floor beams supported both the fourth and second-floor walkways but were only strong enough for 30 percent of that load.
The serious flaws of the revised design were compounded by the fact that both designs placed the bolts directly through a welded joint connecting two C-channels, the weakest structural point in the box beams. The original design was for the welds to be on the sides of the box beams, rather than on the top and bottom. Photographs of the wreckage show excessive deformations of the cross-section. During the failure, the box beams split along the weld and the nut supporting them slipped through the resulting gap, which was consistent with reports that the upper walkway at first fell several inches, after which the nut was held only by the upper side of the box beams; then the upper side of the box beams failed as well, allowing the entire walkway to fall. A court order was required to retrieve the skywalk pieces from storage for examination.
The Hyatt Regency collapse remains the deadliest non‑deliberate structural failure in American history and was the deadliest structural collapse in the US until the collapse of the World Trade Centre towers 20 years later. The world responded to this event by upgrading the culture and academic curriculum of engineering ethics and emergency management. In this, the event shares the legacies of the 1984 Bhopal disaster, the 1986 Space Shuttle Challenger disaster, and the 1986 Chernobyl disaster.
Jack D Gillum (1928 to 2012) was the owner of the engineering company and an engineer of record for the Hyatt project, and he occasionally lectured at engineering conferences for years. Claiming full responsibility and disturbed by his memories “365 days a year”, he said he wanted “to scare the daylights out of them” in the hope of preventing future mistakes.
Sources: Timeline, Kansas City Police Department, Interesting Engineering, Wikipedia