Beware the Mole Man!
The [United Nations University] experts say growing urban land pressure is making it increasingly attractive to find new subterranean space for subways, shopping malls, car parks and other needs.
But Dr Srikantha Herath of the UNU says studies of potential natural disaster risks are often neglected.
He said: "The concentration of people and wealth in such underground spaces is expanding and merits careful examination.
"Such facilities in many areas have not been used sufficiently long to be exposed to various types of extreme hazard events of low frequencies.
"Modelling a variety of catastrophic events is essential for building contingencies into underground infrastructure designs, including evacuations and the emergency containment and transport of flood waters, for example."
So much of interest here. First of all, the phrase "extreme hazard events of low frequencies." One thing the Asian tsunami reminded us of, or should have reminded us of, is that thousand-year-storms never matter unless you're alive when they hit. That is, you can build to probabilities of failure, but when something serious enough happens -- tsunami, earthquake, asteroid -- if you didn't build to withstand that, you look like a shmuck.
That's especially true if your exposure to failure is massive, even if the odds of that failure are low. The UN says that most of the world's megacities are on the water, and built like crap. That's a rough paraphrase of a couple decades of work on megacities, of course, but the point is, the thousand-year storm of 1000 years ago didn't hurt as many people as it would today. More human beings are in harm's way, and that should perhaps change the calculus with which we think about hazard events and low frequencies.
But more proximately, I've been thinking for a while that subterreanizing critical infrastructure might be a good goal for every city. Boston's Central Artery Project, colloquially known as the Big Dig, seemed like a fantastic idea to me. I've lived in Boston twice, once when the Big Dig was just something people were arguing about, and then again when it was almost complete. Both times, despite the almost dutiful corruption, budget overages, and controversies about routes and features, the fundamental notion of returning the Hub to a pre-highway state of nature had a lot of appeal. Anyone who ever had to dodge traffic to get from Haymarket to the North End will probably agree.
Boston has some disaster vulnerabilities, though. As a northeastern city, it's always looking down the barrel of a quake in the Atlantic, or a hurricane that makes it far north. It's also one of the US' major ports for liquid natural gas, which means there's often millions of gallons of high explosive sitting in tanks in the harbor (I'm not giving anything away here; LNG and seaports are a known homeland security problem). But if you put your freeways and mass transit underground, those are the places that flood in an "extreme hazard event," and carry that water places it wouldn't otherwise have gone.
Time to fine-tune those disaster simulations again.