In July 17, 1981, in Kansas City, one of the most tragic engineering failures occurred and caused the death of 114 people and injuring 200 others. The Hyatt Regency Hotel walkway collapse is a dark mark on engineering because it is viewed as a completely preventable accident were it not for some major oversights and missteps by some parties involved. The hotel had only been in operation for a year at the time of the collapse. The ambiguous communication between the structural engineer and the steel fabricator was identified in Missouri’s Administrative Hearing as a major factor in the disaster.

View of the side wall, during the first day of the investigation of the Hyatt Regency walkway collapse.

The reason for the collapse was found to be in the engineering design for the suspended walkways. The original box beam design (which was not actually used) did not meet the requirements of the Kansas City building code. However, the design that was used was even less safe than the original.

Aftermath of the walkway collapse

The structure was built by two companies. One company, Gillum-Colaco, were the consulting structural engineers who built the whole structure. The second company who was involved was Havens Steel Company who oversaw the production of materials involved in the project and also fabricated and raised the walkway. The collapse was caused due to a design flaw involving the rods that held the structure in place. The connections that supported the rods failed. After construction was underway new plans were submitted by Havens and though signed off by Gullum-Colaco were not thoroughly reviewed. Havens changed the design from a one rod connector to a two rod connector to make the building process more efficient but actually weakened the support by doubling the stress on the fourth floor walkway. Gillum-Colaco and Havens had communication problems while this project was underway. Gillum-Colaco prepared the blueprints for the project which Havens used as the final building plan. Gillum-Colaco signed off on the final design which was sent from Havens.

Havens proposed the modified design to simplify the assembly task and to eliminate the need to thread the entire length of the rods. However, the change in the design doubled the stress put forth on the nut which was under the fourth-floor beam and with the change the nut had to support the weight of two walkways instead of just one. “The ultimate capacity actually available using the original connection detail would have been approximately 60% of that expected of a connection designed in accordance with AISC Specifications” according to the National Building Specifications. The project then began construction otherwise the design flaw would have been discovered in the connector rods. Construction on the Hyatt-Regency hotel in Kansas City, MO stated in 1978 and was opened in 1980.

What went wrong??
The box beams resting on the supporting rod nuts and washers were deformed because of the stress that was exerted on them. The box beam resting on the nuts and washers on the rods could no longer hold up the load. The box beams (and walkways) separated from the ceiling rods. The second and fourth floor walkways fell to the atrium first floor with the fourth floor walkway coming to rest on top of the second.

Learnings from the accident

Upon understanding the cause and fault of this engineering disaster, we can look at how this disaster could be prevented and learned from. This was a preventable disaster if the engineering firm noticed, and corrected the change, or if WRW properly re-engineered the change to be able to handle the new loads introduced. Ultimately, Gillium, the engineering firm, is at fault for approving unsafe drawings but an argument can be made that WRW is at fault as well. Ethically, it is a grey area as to who is responsible, the lead engineering firm for missing the inadequacy of the engineering change or the subcontractor who made the change incorrectly. Because of the encompassing responsibilities of the engineering firm, they are to take the brunt of the blame.
What we can take from this disaster to prevent others is the need for constant quality checks and the willingness by companies to pay for this. The economic pressures that weigh in on projects cannot be ignored, however, public safety must be put above those issues. Also, review during any engineering change, however small, should have experts eyes on them and if possible, as many eyes as possible to prevent unpreventable human error. A set review process should always be used as it forces a change to go through a proven system and limits he-said, she-said battles. Written proof of review and verification is essential to prevent disaster and avoid misguided blame.

The ambiguous communication between the structural engineer and the steel fabricator was identified in Missouri’s Administrative Hearing as a major factor in the disaster. The Commission report states that the structural engineer “bears the burden of communicating his intent to the contractor and assumes the risk of confusion or noncommunication.” The report also states, “…the burden and responsibility for clear communication lies with the engineer who assumes the risk of ambiguity in his design drawings.”

In line with another learning outcome is the understanding of professional responsibility and its ethical implementation by the Hyatt’s structural engineer. Despite making assurances to the owner and architect of doing so, the structural engineer never ran calculations on the flawed connection. In addition, the structural engineer and the steel fabricator did not properly coordinate their responsibilities in the connection design; and in their rush to complete the job, the critical shop drawings never got a proper review despite the engineer’s review stamp. Valuable opportunities exist in such a teachable case study to highlight important professional issues in communications, professional responsibilities, professional ethics, and interdisciplinary teamwork.