It goes without saying that this is a disaster:
At least four people have been killed and 10 others hurt after a footbridge collapsed near Florida International University in Miami, officials say.
The 862-tonne, 174ft (53m) bridge fell over an eight-lane motorway on Thursday afternoon, crushing at least eight vehicles, police said.
They told local media that vehicles were stopped at a traffic light when the structure collapsed at about 13:30 local time (17:30 GMT).
It is still unclear how many people were under the bridge at the time.
For a standard, single-span footbridge to suddenly collapse in this manner in the United States in 2018 is incredible. Reinforced concrete footbridges have been built worldwide for decades, and ought to be the sort of thing a highways department can design and build on their own. Perhaps one 53m long over an 8-lane highway requires some specialist assistance, but still. This was not the Millau Viaduct.
These days engineering firms use finite element modelling (FEM) programs which can predict how a structure will perform under load, identify any weak points, and calculate the stresses induced in every location. The bridge which collapsed looks to be of an unusual design, no doubt approved by an architect somewhere, but that is precisely what the FEM models are for. Using them you can depart from a traditional design, incorporate architectural features, and still be sure your structure is sound. A newly installed footbridge suddenly collapsing onto traffic in the US is the equivalent of a batch of canned goods killing people, the contents having reacted to the metal. There is enough knowledge and experience by now to ensure these sort of accidents no longer occur.
Yet it did, so why? The BBC tells us this:
The bridge was erected on Saturday in just six hours.
It was built using a method called “accelerated bridge construction” to avoid traffic disruption. A major section of the bridge was assembled on the side of the road and then raised into place.
I’ve written before about bridge collapses, and how they tend to happen during construction, but I don’t think the installation method described above had anything to do with it. There’s a video here of the bridge being installed, and it looks to me like a pretty common technique which doesn’t in itself explain why it collapsed a few days later.
So here’s my guess: somebody screwed up the calculations or the finite element model, and nobody picked up the error. If this was in the developing world I’d be more inclined to believe it was shoddy construction or poor materials rather than a design error, but this being the US I can’t see that happening. The company that carried out the engineering was Munilla Construction company, a family-owned firm whose website is here. They’re based in Miama and have been around since 1983 and they claim:
WE BUILD YOUR PROJECT ON TIME, ON BUDGET, AS DESIGNED AND WITHOUT ANY SURPRISES.
They might want to update that at some point.
What follows is pure speculation on my part but it’s based on what I’ve observed of engineering companies and corporations over the past 15-20 years or so. Back in 1983 the firm would have employed serious engineers who held themselves accountable, and the brothers who founded it probably did a lot of the work themselves. There is no doubt this company was able to successfully deliver engineering projects for a couple of decades, so they’re not some fly-by-night outfit owned by the wife of the local mayor.
But I suspect things changed sometime in the past 5-10 years. There is nothing on the company website to suggest they succumbed to the relentless pressure placed upon firms to hire people based on their appearance and sex rather than competence and ability, but I’d be surprised if they were wholly unaffected by demands for greater workforce “diversity”. After all, this was a firm which did several projects for the public sector, and installed the bridge on behalf of a university. It’s unlikely they weren’t required to demonstrate they were fully on-board with the latest progressive directives. At a guess, I would say this is a company which has seen several experienced engineers retire over the past decade, replaced with people whose abilities are questionable.
Secondly, as I have complained about in the past, there has been a major shift in modern companies from delivering something useful – such as a bridge which doesn’t collapse – to managing processes. A lot of companies have subcontracted out the actual work – designing, building, manufacturing, operating, maintaining – and instead busy themselves with “managing” the whole process. This involves lots of well-educated people in nice clothes sitting in glass-fronted office buildings sharing spreadsheets, reports, and PowerPoint presentations by email and holding lengthy meetings during which they convince one another of how essential they are. I’m sure this is pretty much what Carillion was doing when they went bust: anything useful was done by subcontractors. The distance between those doing the actual work and those supposedly responsible for the outcome has, in far too many companies, grown into a yawning chasm. Survival in a modern company is all about compliance and obedience, and accountability is non-existent because it is no longer required.
In such an environment, it is inevitable that the quality of work suffers, errors go unnoticed, and – occasionally – catastrophes occur. Now I don’t know if that was the case at the Munilla Construction company, but somehow they’ve gone from an outfit who could deliver a project with their eyes closed to one that has just dropped a simple footbridge on eight lanes of highway. If I were investigating, I’d want to know who did the actual design and where it was done. I’d be willing to bet a hundred quid the calculations and finite element modelling were done outside the US to save money, or subcontracted to another company, and supervision – which involves expensive Americans – was at nowhere near the levels it should have been. Regardless of where they were done, I’d also be willing to bet the company spent more manhours on progress meetings and overly-detailed weekly reports to let the management know what was going on than they did checking the engineering calculations.
I might be wrong, and maybe I’m being unfair to the Munilla Construction company. But I’m not wrong in describing how modern companies work. I have a hunch we’re going to see more disasters like this in the coming years as successive generations of managers and engineers fail to deliver what were, until recently, pretty ordinary projects.
David Moore posts a link to this video which reckons the bridge was supposed to be supported from above using cables in the final design. If they’re right, then this is a classic case of a poorly-supported bridge span collapsing during construction, and we can all go and read my previous post. It doesn’t make the cock-up any less severe though, just slightly more understandable.