The Johnson Commission into the De la Concorde overpass collapse submitted its final report to the government last week. The report, which is 222 pages long, is available (in English!) as a PDF on its website. (The last page of the report laughingly self-congratulates how much it’s saving the environment by printing on recycled paper, even though the previous page is entirely blank.)
(Above: the last photo taken of the De la Concorde overpass before its collapse, by a Transport Department road supervisor sent to pick up some fallen concrete. The commission absolved him of responsibility since he wasn’t an engineer.)
In short, the causes of the collapse were as follows (disclaimer: I’m not an engineer, so some of my explanations might be a bit off):
- Improper, low-quality concrete used in its construction, in turn blamed on confusing design instructions and insufficient supervision.
- Improper placement of reinforcing steel rebar.
- Insufficient drainage, leading to water, ice and salt weakening the concrete.
- Insufficient supervision and inspection of construction.
- Common practices in use during the time of construction that science would later show needed reinforcing to counter the effects of concrete shear.
- Missing documentation at the MTQ concerning the structure’s construction and repair history.
- Improper repair of the structure in 1992, which ended up weakening the structure.
- Insufficient and inadequate inspections, with imprecise inspection reports.
All that comes down to the big cause: cutting corners to save money. Cutting corners on inspections, on materials, on competence, on time. Each, by itself, isn’t dangerous. But put enough together and they spell disaster. The blame was, in the end, so spread out that no individual can be considered liable.
So now the government is going to create an independent agency for road inspections (to counter the “culture of negligence” at the MTQ) and spend billions of dollars to catch up on infrastructure maintenance.
What gets me about all this is that the transport department (and the commission itself) has been working overtime trying to convince everyone that our structures are safe.
The implication in that is that the de la Concorde overpass collapse was a one-time thing. A fluke that can’t be repeated. But while there were a lot of coincidental mistakes that contributed to the collapse, not a single one of them is guaranteed not to have occurred with other structures. There’s no guarantee that there isn’t a structure out there with bad concrete, or improperly-placed steel supports. Nothing stops a similar collapse from happening to another structure.
That said, the transport department has already changed the way it maintains overpasses, and has inspected many of them thoroughly. The culture of negligence and cost-cutting corner-cutting has, for now, been replaced with a healthy fear of a similar event happening again.
It’s debatable how long that fear will last. After the Challenger space shuttle exploded in 1986, NASA started to become overly cautious about safety in its missions. But eventually cost-cutting reared its ugly head in 2003 when the Columbia burned up on re-entry. Though the direct causes were different, reports cited an attitude at the organization that encouraged disregarding small risks to keep missions going.
Hopefully we won’t forget the lessons of de la Concorde in 20 years just to save a few bucks.