<P> The construction of the 40 - story Hyatt Regency Kansas City began in May 1978 . Despite delays and setbacks, including an incident on October 14, 1979, when 2,700 square feet (250 m) of the atrium roof collapsed due to the failure of one of the connections at its northern end, the hotel officially opened on July 1, 1980 . </P> <P> One of the defining features of the hotel was its lobby, which incorporated a multistory atrium spanned by elevated walkways suspended from the ceiling . These steel, glass and concrete crossings connected the second, third and fourth floors between the north and south wings . The walkways were approximately 120 ft (37 m) long and weighed approximately 64,000 lb (29,000 kg). The fourth level walkway aligned directly above the second level walkway . </P> <P> On the evening of July 17, 1981, approximately 1,600 people gathered in the atrium to participate in and watch a tea dance . At 7: 05 p.m. local time (00: 05 UTC; July 18) the second - level walkway held approximately 40 people with more on the third and an additional 16 to 20 on the fourth level who watched the activities of the crowd in the lobby below . The fourth - floor bridge was suspended directly over the second - floor bridge, with the third - floor walkway offset several meters from the others . Construction difficulties resulted in a subtle but flawed design change that doubled the load on the connection between the fourth - floor walkway support beams and the tie rods carrying the weight of both walkways . This new design was barely adequate to support the dead load weight of the structure itself, much less the added weight of the spectators . According to the Seconds From Disaster episode, many of the survivors reported hearing popping noises coming from above them shortly before the collapse . Only moments later, the fourth - floor walkway suddenly dropped several inches under the spectators, before falling completely onto the second - floor walkway . Both walkways then crashed to the lobby floor below, resulting in 111 deaths at the scene and 219 injuries . Three additional victims died after being transported to hospitals, bringing the total number of deaths to 114 . </P> <P> The rescue operation lasted 14 hours and was performed by many emergency personnel, including crews from 34 fire trucks and EMS units and doctors from five local hospitals . Trapped survivors were buried beneath more than 60 tons of steel, concrete and glass, which neither the Hyatt's forklifts nor the fire department's most powerful jacks could move . Additional volunteers from surrounding areas responded to the fire department's requests for help, including construction companies and building - supply stores, bringing hydraulic jacks, acetylene torches, compressors, jackhammers, concrete saws and generators . Kansas City's natural disaster response team, known as "Operation Bulldozer", was also summoned to the scene with earthmoving equipment, but was quickly sent away to make room for cranes that would lift the sections of walkway off the trapped survivors . Dr. Joseph Waeckerle, former chief of Kansas City's emergency medical system, directed the rescue effort establishing a makeshift morgue in a ground floor exhibition area, using the hotel's driveway and front lawn as a triage area and helping to organize the wounded by greatest need for medical care . Those people who could walk were instructed to leave the hotel to simplify the rescue effort; those mortally injured were told they were going to die and given morphine . Often, rescuers had to dismember bodies to reach survivors among the wreckage . One victim's right leg was trapped under an I - beam and had to be amputated by a surgeon, a task which was completed with a chainsaw . </P>

Explain how the hyatt regency hotel walkway in usa collapse on july 17 1981
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