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.
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