In 1900 Philadelphia, then the third-largest city in the
U. S. with a population of over one million, was a bustling metropolis whose
downtown streets were lined with three-and four-story department stores and
other structures, such as the four-story brick edifice built by some
enterprising Philadelphians at 2136-2138 Market, near the corner of 22nd and
Market Streets. Over the years,
the building saw a variety of uses.
Its facade was modernized, but its basic construction of brick augmented
with steel beams remained unchanged.
Finally, in May of 2013, the current owners of the structure decided to
take it down. And here is where
the building entered the annals of engineering-ethics tragedies.
The safest way to take down a brick building is by
reversing the way it was constructed:
that is, brick by brick.
Such an approach is prohibitively expensive, so demolition firms use
more efficient methods, such as wrecking balls and hydraulic excavators (a type
of heavy machinery with a long hydraulically operated arm and a scoop at the
end). The problem with brick walls and demolition operations is
that the walls have almost no tensile strength on their own, if they are unsupported
by an all-steel framework or facade.
While properly built brick buildings can reach heights of fifty feet or
more and last for thousands of years, any substantial sideways force on the
structure cracks the mortared joints between the bricks and turns the thing
into a big pile of loose bricks, which do unpredictable things. This is why Sean Benschop, the man
operating the hydraulic excavator at the Market Street demolition site, was
taking a huge risk as he worked to take down the remaining parts of the
113-year-old structure he was hired to demolish.
While demolition operations fall under the purview of the
City of Philadelphia’s building inspectors, and a permit was required to begin
the demolition, no inspections were carried out during the demolition
itself. If a city inspector had
happened by on Sunday, June 2, he might have seen what a passerby videoed that
afternoon and subsequently posted on YouTube.
The four-story building in question faced the street, and
to its immediate right as you faced its front was a one-story Salvation Army
thrift store on the corner of 22nd and Market. Both buildings were long and narrow and extended parallel to
each other about half a block to the rear. On that Sunday afternoon, someone (presumably Mr. Benschop)
had moved his hydraulic excavator onto the sidewalk in front of the thrift
store, and was going after the remnants of the front wall, which was about two
stories high at that point. An
assistant played a spray of water on the wall, presumably to keep down
dust. But the video clearly shows
bricks falling from the front wall onto the sidewalk, which is apparently open
to anyone who would be foolish enough to approach the scene and risk getting
hit by falling bricks. No one had
erected the open plywood-box type of shelter for sidewalks that is customary at
constructions sites that border the street. Even more ominous in this scene is the right-hand side wall
of the old building, which has been partly removed near the front but looms
near its full original height toward the back, rising above the one-story
Salvation Army store.
It was that wall which collapsed outward on Wednesday
afternoon, June 5. A still photo
taken moments after the collapse shows panicked passersby running away from the
huge cloud of tan dust that arose.
Six people died in the store, which was open for business as usual that
day, and one woman was pulled alive but seriously injured from the wreckage
after being buried for 13 hours.
Thirteen people in all were injured.
Who was responsible for this accident? From a legal point of view, that
question will be examined exhaustively, because on it hinges the question of
financial damages and possibly criminal penalties. But from the viewpoint of engineering ethics, we ask the
question with the main goal of preventing such tragedies in the future. In order to fix a chain of
responsibility, one must first understand how it broke down.
The news media have focused on Mr. Benschop, in whose
system traces of marijuana was found, and whose criminal record includes ten
arrests for matters such as drug charges, theft, and assault. Mr. Benschop does not appear to be a
moral exemplar. He may have been
doing his job as well as he knew how, and was capable of doing at the time, but
from the results, that was not near good enough. He turned himself in to authorities Saturday and proceeded
to have the book thrown at him.
The next step in the chain of responsibility is the person
who hired Mr. Benschop, who according to news reports was contractor Griffin
Campbell. Mr. Campbell, who has
been cited by city inspectors for violations at other demolition sites his firm
was operating, filed for bankruptcy earlier this year, according to a New York Times report.
Further up the chain, Mr. Campbell’s firm was hired by STB
Investments, the legal owner of the building. The principal owner of STB Investments is Richard Basciano,
who is described by the Times as “a
dominant figure in the sex industry.”
He decided to tear down the building in question as well as several
other properties in the area to make it more attractive for developers.
Demolition contractors must obtain permits from the City
of Philadelphia, and the city’s inspectors are in some sense responsible for
the work permitted under such measures.
We will probably find out a lot more about how the permitting and
inspection process works during the upcoming investigation. No inspection regime can guarantee 100%
safe outcomes without being prohibitively costly and oppressive, but it is a
good question whether this accident has revealed lapses or shortcomings in the
inspection and permitting process.
In principle, the operators of the thrift store could have
decided things were looking too risky as the building next door was demolished,
but this would have required a level of judgment and expertise that is not to
be expected from the manager of a thrift store. So the occupants and customers in the thrift store are the
innocent victims of this miscarriage of engineering, and bear essentially no
responsibility for what happened.
When something like this goes wrong, there are often calls
for more rules and regulations.
One reporter pointed out that existing OSHA regulations require that any
wall higher than one story must be supported by bracing unless it was designed
not to need any, even during a demolition operation. The wall that collapsed clearly was not braced, so the
regulations were there. They
simply weren’t observed.
If changes in the way demolition is regulated are needed,
let’s hope that the investigation into this collapse leads to intelligent and
reasonable improvements that avoid such tragedies in the future.
Sources: I referred to the following news items
published online: ABC News at http://abcnews.go.com/US/excavator-operator-surrenders-philadelphia-building-collapse/story?id=19356293#.UbRZmJV4WsM,
USA Today at http://www.usatoday.com/story/news/nation/2013/06/05/pa-building-collapse-philadelphia/2391943/,
Engineering News-Record at http://enr.construction.com/yb/enr/article.aspx?story_id=186497987,
the New York Times at http://www.nytimes.com/2013/06/07/us/philadelphia-building-collapse.html,
and the Wikipedia article on the collapse “22nd and Market
building collapse”. The age of the
building was obtained from the website http://www.propertyshark.com/mason/Property/22963127/2136-2138-Market-St-Philadelphia-PA-19103/,
and the YouTube video of the demolition taking place on June 2 is posted at http://www.youtube.com/watch?v=gnl1UcwJGfs.
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