No Do-Over for New Orleans Hard Rock Hotel

There is a saying I've heard more than once from fellow engineers involved in a rush job:  "There's not enough time to do it right, but there's always enough time to do it over."  In other words, sometimes the only way managers will give engineers enough time to do a thing right is if it fails the first time.  Unfortunately for three construction workers who died and numerous other people injured and otherwise harmed by the collapse on Oct. 12 of the Hard Rock Hotel under construction in New Orleans, there will not be any do-overs.  On Nov. 13, New Orleans officials announced that the severely damaged hotel structure will be imploded and razed to the ground.  This will bring to a sad end the physical aspects of the tragedy that began last October, but won't by itself answer the questions of why the collapse happened. 

In the weeks since the collapse, a video emerged that was made by a construction worker on site just two days before the accident.  It shows severely bowing supports between the just-poured top floor and the floor below it.  A reporter for WWL-TV posted a story in which another construction worker said that temporary supports between the top two floors were removed only three days after the concrete was poured.  The same report cites industry standards that say the minimum time between pouring and removing temporary supports should be two weeks.  Reportedly, workers were under heavy pressure by supervisers to complete the building before the busy Mardi Gras tourist season in February. 

Another WWL report says that a large swimming pool was apparently lifted by crane to the top of the building just hours before the collapse.  Even if empty, a swimming pool shell must weigh several thousand pounds, adding additional stress to concrete that was possibly already weakened by the premature removal of supports. 

While these facts raise suspicions, no definite conclusions can be drawn until the official investigations now underway are completed.  Nevertheless, the accident and what is known about it so far serve as reminders of some age-old truths about engineering that are always helpful to remember.

First, practical engineering is always a business of compromises.  Any engineering project is an attempt to stay within multiple limits:  limits of cost, limits of time, limits of physical capabilities of materials, limits of hazards, and so on.  A project is deemed to be successful when it achieves something desirable without exceeding any of the important limits that applied to it.  Sometimes one or two limits are exceeded, but if the consequences of exceeding these limits are minor, they can be neglected.  For example, if a project slightly exceeds budget or is completed only a few days late, usually those involved just absorb the cost and keep going.

It begins to look like the Hard Rock project put speed above a lot of other priorities, including safety.  Now, construction projects can be completed faster than the average time that is usually allotted to them.  To some extent, money can be traded for time.  I recall a passage from the autobiography of Albert Speer, Hitler's architect who later became Germany's Minister of Armaments and War Production during World War II.  Right after Hitler hired him in the 1930s, Speer was handed the job of redecorating the official residence of the Minister of Nutrition for Hitler's associate Joseph Goebbels, and Speer promised to do the job in the exceptionally short time of only two weeks.  In order to impress his new boss, Speer spent extra money on three shifts of additional workers and rented big fans to blow drying air through the building to dry the paint faster, and reported completion to his boss right on schedule.

Not that Nazis are moral exemplars by any means.  This is just a historical anecdote showing how construction projects can be safely sped up at additional cost.  But concrete is not as forgiving as paint.  There are special fast-setting concrete mixtures, but even those require the specified minimum time to set, and tests are required to verify that the concrete is firm enough to hold its own weight without extra supports that are installed during the pouring process. 

It's easy to watch a construction site with workers swarming around it like bees, and think that everything just goes smoothly by default or instinct.  What is not visible to the eye is the complex management structure that has to be in place in order for the dozens or hundreds of lowest-level workers to know what they are supposed to do, and when and how they are supposed to do it.  Having engaged in management myself just enough to know I don't like it, I can only imagine what it takes to run a large-scale building project such as the hotel that collapsed in New Orleans.

In the coming months and years, lawyers as well as official investigators will dissect the management structure, the physical structure, and the complex sequence of events that led to the tragedy of Oct. 12.  Major disasters rarely have a single cause without which everything would have been just fine.  A combination of factors is usually at fault, so we may find that schedule corner-cutting, weather conditions, and an unfortunate sequencing of events such as raising the swimming pool to the top of the building were all partly responsible for the collapse.  But until this information is made public, we can only speculate.

In the meantime, the loved ones and friends of two workers whose bodies remain in the rubble will have to wait until after the intentional implosion of the building to find if there is anything recoverable.  The structure is still unstable and too dangerous to search in, even after an attempt to implode the damaged construction cranes on the site.  And the construction and engineering communities await the post-mortem on this major tragedy to learn whatever lessons can be learned from it. 

Sources:  I referred to an article carried on www.nola.com on Nov. 1 at https://www.nola.com/news/article_64e1c72a-fcf3-11e9-b3a6-a723e997693e.html, an article republished by USA Today from the Lafayette Daily Advertiser on Nov. 13 at https://www.usatoday.com/story/travel/news/2019/11/13/hard-rock-hotel-new-orleans-to-be-demolished/4180871002/, and an article on the WWL-TV website describing the swimming-pool lift at https://www.wwltv.com/article/news/investigations/pool-lifted-to-rooftop-of-hard-rock-hotel-just-hours-before-collapse/289-6d12ee9e-0379-4837-a946-1d1b7b66ba94.  The anecdote about Goebbel's official residence is on p. 32 of Albert Speer, Inside the Third Reich (Macmillan, 1970).  I thank David Jenkins for bringing my attention to some of this additional information.

Hard Rock Hotel Collapse: Why?

On Saturday morning, Oct. 12, a hotel under construction at the corner of Rampart and Canal streets in New Orleans, Louisiana underwent a partial collapse, killing three workers and injuring 30.  The Hard Rock Hotel, originally planned as a mixed retail/residential project, had reached a height of 13 stories when something happened to cause a collapse at the top completed level.  A chain of floor collapses ensued, leading to a partial collapse of all the floors above about the seventh level.  The collapse also damaged the two tower cranes that were being used on the project, leading to concerns that they might fall and damage some of the surrounding structures in the densely populated downtown area.  At this writing (Wednesday, Oct. 16), the body of one worker has yet to be recovered.

Any time a construction accident occurs, the entire complex process of planning, management, and actual construction activity gets called into question.  The construction of a large high-rise such as the Hard Rock Hotel is an exercise in meticulous coordination and integration of technologies ranging from computer-aided design to the kind of pumps that can send many tons of concrete all the way up to the roof of a 13-story building.  With so much heavy stuff being supported in temporary ways, it's understandable that something could go wrong. 

For example, the concrete floors that are poured at each level have to set before they are put into compression by tensioning cables.  Try to tighten those cables too early, and you're liable to squash the still-weak concrete.  But wait too long by a day or so, and you've added costly time to the construction schedule.  A huge number of time-critical matters have to be coordinated within a small margin of error for things to go smoothly, and weather, supplier problems, and other external factors can throw a monkey wrench into the works. 

Still, most buildings go up without having multiple floors collapse on each other.  Viewed from the front, the structure looks like a giant finger just scraped all the floors above the seventh and bent them downward. 

A structural engineer named Walter Zehner once worked on the project in its early stages.  When contacted by a reporter from the Lafayette Daily Advertiser, he said that it was much too early even to speculate on the cause of the collapse.  After retreival of the remaining fatality, engineers will have to stabilize the structure so that it won't present an ongoing hazard to surrounding buildings.  Only then will the investigation begin, and it might take months.

Construction was in progress at the time of the collapse, and Zehner says that the remaining eyewitnesses will be asked what exactly was being done at the time.  It's possible that someone accidentally knocked over a support column, for example.  If a heavy just-poured layer of concrete falls twelve or fifteen feet onto the floor below it, the impact could well cause the next floor to collapse, leading to just the kind of destruction that took place.  But all such notions are speculation at this point, and the investigation will reveal a sequence of events that may be traced backwards to a possible cause.

In the recent past there have been some indictments of city inspectors for taking bribes.  A lack of proper municipal oversight might lead to hazardous conditions that could cause such a collapse, but again, this is speculation. 

The most recent collapse of a structure under construction that was covered in this blog was the Florida International University pedestrian bridge collapse in Miami in 2018.  Six people were killed when a concrete-beam bridge collapsed just after being set in place.  The investigation of that accident is still ongoing, but late last year it was revealed that the National Transportation Safety Board (NTSB) had determined design errors were at least partly to blame. 

Accidents like the Hard Rock Hotel collapse can happen even if the plans are flawless.  The 1981 collapse of a pedestrian walkway inside the atrium of the Hyatt Regency Hotel in Kansas City was due not to any flaws in design, but to a compromise that the builder made in the support structure during construction.  Investigations may reveal that while the New Orleans hotel plans were correct, the builders may have overlooked something.  Or it could turn out that a single mistake made by one construction worker led to the tragedy. 

Not much is known about the extent of training that typical construction workers receive.  Construction is one of the few remaining fields in which a person without a high-school degree can earn at least in the range of $13 an hour, which is the average construction-worker wage in Louisiana according to a statistic cited by the website indeed.com.  This is scarcely anything to write home about, unless home is Guatemala, in which case it looks good compared to trying to be a subsistence farmer.  Nevertheless, it's attractive enough to draw workers who are willing to face the dangers and difficulties that construction work involves, up to and including the chance of dying in a tragic accident.

We will have to wait to find out what exactly happened in New Orleans to transform a nearly completed building into a pile of dangerous rubble.  And when we do, I hope that any lessons learned will be applied to future construction sites so that tragedies like this happen less and less frequently. 

Sources:  I referred to reports from the ABC News website at https://abcnews.go.com/US/search-underway-unaccounted-person-hard-rock-hotel-partially/story?id=66261708, the Lafayette Daily Advertiser website at https://www.theadvertiser.com/story/news/2019/10/14/hard-rock-hotel-collapse-new-orleans/3979427002/, and the Wikipedia website "List of structural failures and collapses."  The hourly construction wage statistic came from https://www.indeed.com/salaries/Construction-Worker-Salaries,-Louisiana.  I discussed the FIU bridge collapse at https://engineeringethicsblog.blogspot.com/2018/12/design-flaw-identified-in-fiu-bridge.html.