In 1900 Philadelphia, then the third-largest city in the United States 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 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 percent 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.
Karl D. Stephan is a professor of electrical engineering at Texas State University in San Marcos, Texas. This article has been republished, with permission, from his blog, Engineering Ethics, which is a MercatorNet partner site.