The Hyatt Regency Walkway Collapse: A Tragic Engineering Failure

On July 17, 1981, a disaster struck the Hyatt Regency Hotel in Kansas City, Missouri, when two overhead walkways collapsed onto a crowded lobby, killing 114 people and injuring 216. It was one of the deadliest structural failures in U.S. history and a shocking reminder of the importance of engineering ethics and safety.

Background on the Project

The Hyatt Regency Hotel was a 40-story building that opened in July 1980, after two years of construction. The hotel’s lobby was its defining feature, with a multi-story atrium spanned by three elevated walkways suspended from the ceiling. The walkways connected the second, third and fourth floors from north to south and were made of steel, glass and concrete. Each walkway was about 37 meters long and weighed about 29,000 kilograms.

The hotel was designed by the architectural firm PBNDML (now part of Gensler), and the structural engineering was done by Jack D. Gillum and Associates (later G.C.E. International). The general contractor was Eldridge Construction Company, the steel fabricator was Havens Steel Company, and the steel erector was United Iron Works.

The Collapse and Its Causes

On the night of July 17, 1981, the hotel hosted a tea dance in its lobby, which attracted about 1,600 people. Many of them gathered on the walkways to watch the band and socialize. At around 7:05 p.m., the second- and fourth-floor walkways suddenly broke free from their support rods and fell onto the first-floor walkway and the lobby floor below, crushing hundreds of people under tons of debris.

The collapse was captured on video by a local television crew that was covering the event. The video showed people screaming and running for their lives as dust and smoke filled the air. Rescue workers arrived at the scene and began to dig through the rubble, using torches, cranes and jackhammers. Some survivors were trapped for hours before they could be freed. Others died from their injuries or suffocation.

The investigation into the collapse revealed that a design change during construction was the main cause of the failure. The original design called for six steel hanger rods to run directly from the second-floor walkway to the ceiling for support. However, the steel fabricator objected to this design, as it required threading each rod twice to hold both walkways in place. The fabricator proposed a new plan: a set of tie rods that connected the fourth-floor walkway to the ceiling and a separate set that connected the second-floor walkway to the fourth-floor walkway.

This plan was approved by the structural engineer without checking its feasibility or safety. The problem was that this plan doubled the load on the upper hanger rods of the fourth-floor walkway, as they had to support both walkways instead of one. The load exceeded the capacity of the rods and their connections by more than 60%. Moreover, the box beam flanges that held the rods were welded instead of bolted, creating weak points that could easily fracture.

On the night of the collapse, the weight of the people on the walkways added more stress to the already overloaded structure. The fourth-floor box beam flange failed first, followed by the second-floor box beam flange. The rods pulled through their holes and snapped, sending both walkways crashing down.

Lessons Learned

The Hyatt Regency walkway collapse was a tragic engineering failure that could have been prevented with proper design review, communication and quality control. The collapse led to several lawsuits, settlements and criminal charges against some of the parties involved. It also resulted in changes in building codes, engineering standards and professional ethics.

Some of the lessons learned from this disaster are:

• Engineers should always check their calculations and assumptions before approving any design changes.
• Engineers should communicate clearly and document any design changes with all parties involved.
• Engineers should follow up on any concerns or questions raised by contractors or fabricators.
• Engineers should adhere to their codes of ethics and protect public safety above all else.
• Engineers should learn from their mistakes and share their knowledge with others.

The Hyatt Regency walkway collapse is a warning from history to all civil engineers today. It reminds us of our responsibility to design safe and reliable structures that can withstand various loads and conditions. It also challenges us to improve our skills and practices to prevent such failures from happening again.

If you want to learn more about the Hyatt Regency walkway collapse, here are some links to more information:

• [Hyatt Regency walkway collapse — Wikipedia](https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse) ²
• [Hyatt Regency Collapse Remains Among The Deadliest In U.S. History — NPR](https://www.npr.org/2021/07/17/1016603199/one-of-the-deadliest-u-s-accidental-structural-collapses-happened-40-years-ago-t) ¹
• [Hyatt Regency walkway collapse | Cause, Description & Facts — Britannica](https://www.britannica.com/event/Hyatt-Regency-walkway-collapse) ⁴

Source: Conversation with Bing, 6/9/2023
(1) The Hyatt Regency Walkway Collapse — Dailymotion. https://www.dailymotion.com/video/x7xzbk6.
(2) Hyatt Regency walkway collapse — Wikipedia. https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse.
(3) Hyatt Regency Collapse Remains Among The Deadliest In U.S. History — NPR. https://www.npr.org/2021/07/17/1016603199/one-of-the-deadliest-u-s-accidental-structural-collapses-happened-40-years-ago-t.
(4) Hyatt Regency walkway collapse | Cause, Description & Facts. https://www.britannica.com/event/Hyatt-Regency-walkway-collapse.
(5) Hyatt Regency walkway collapse: 40 years ago today one of America’s …. https://www.independent.co.uk/news/world/americas/hyatt-regency-walkway-collapse-kansas-b1885876.html.
(6) Understanding the Tragic Hyatt Regency Walkway Collapse. https://interestingengineering.com/culture/understanding-hyatt-regency-walkway-collapse.
(7) Hyatt Regency Walkway Collapse | Online Ethics. https://onlineethics.org/cases/hyatt-regency-walkway-collapse.