• Field Notes 10.10.2012

    In July 1981, two pedestrian bridges spanning approximately 120 feet across the atrium at the second and fourth levels of the Kansas City Hyatt Regency hotel collapsed during a happy hour tea party, killing 114 people and injuring 216 others.  Investigators later found that a change during construction in how the lower bridge was supported and tied to the roof ultimately led to the collapse.  The design professionals involved had reviewed and signed off on the change.  They eventually lost their professional licenses, which is minor compared to the lives that were inalterably changed that day. What lessons does that tragedy have for us today?

    A recent article in Structural Engineer magazine brought the Hyatt incident to mind.  Missouri has passed a “peer review” law that seeks to encourage outside, independent project reviews. The law provides protection from liability for design professionals who participate in peer reviews prior to construction, as well as for teaching “lessons learned” sessions for completed projects. The goal is to reduce errors and omissions and identify best practices for future designs.

    Not that this type of practice would have averted the Hyatt disaster, but what a paradigm shift!  The design change made at the Hyatt occurred during shop drawing and / or structural calculation review while the project was underway, not before or after it was completed (as is addressed in the Missouri peer review law).   The glass and glazing world has been pretty fortunate that there hasn’t been anything that’s happened on the scale of the Hyatt, but imagine if this peer review trickles into our industry.

    Mind you, Missouri’s peer review law is about design professionals reviewing other design professionals’ work.  To me, that’s civil or structural engineers and architects.  And with most of the glass and glazing structural calcs being prepared by licensed professional engineers, I’ve yet to hear of an instance when the calculations were so wrong, or the detailing so off that led to walls or glass falling off.  I’ve seen instances where the execution has been off, but always that’s caught, corrected, and the final products have stayed in place.

    Having had a seat on the consulting side of the table has let me see the glass/glazing world from a different perspective.  One of the first site observation visits I ever made was to a project in which the glazier set glass with cardboard in the glazing channel because they had run out of gasketing.  But they were setting lites, and the cardboard was not sufficient to stop glass / metal contact.  The glass rattled around in the glazing pocket, not a good situation.

    On another project, the installers were setting glass on 2-inch-long setting blocks.  When I asked why they were not using longer blocks (the shop drawings called for 6-inch-long blocks), they said they’d been using 2-inch-long blocks their whole (5 years, it turned out) glazing life.  I told them in 25 years, I had never seen a situation where 2” blocks were permissible.  When I got back to the office, someone mentioned an even better retort to the ‘I’ve been doing it that way my whole life’  line:  ‘Then you’ve been doing it wrong the whole time.’

    When I went back to that same project a few weeks later, they had changed to longer setting blocks, but were using shorter horseshoe shims under the blocks to account for the uneven glass edge.  No matter how good the drawings and calculations, it still comes down to following the drawings.  God bless the tradesmen, be they ironworkers, glaziers, or caulkers, who are dedicated to doing things right.  We owe them as much as anyone else involved.

    But getting back to peer reviews, it’s not time to do this in the glazing world yet.  One, we’re too close to each other in a very competitive market to allow each other to review drawings, means / methods, or other trade secrets.  Second, consultants fill this role within the industry.

    A long time ago, and not recalling where I first heard it, someone said, “You have to know what you know, but more importantly, you have to know what you don’t know.”  If you don’t know, and you know that, you ask questions, or you hire people to do that for you.  I’m not a structural engineer, so I take those questions to someone who is.

    As a general rule, this is typically what happens in the glazing world.  There are enough people out there to help, be they structural engineers, consultants, or others who can and will help.  Let’s continue to do that.  Peer reviews, if and when they do happen in this business, often happen at the courthouse.  No one likes to be in those situations.

    Hopefully we’ll never have a Hyatt, or anything close to it, happen in this industry. Again, let’s be careful out there.

    Posted by Bryan @ 9:20 am

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