Earlier this year, I wrote about the French town of Bar-le-Duc, where part of my family comes from. It’s an old place, some of it very old – the architecture of different periods building up in layers. It’s not unusual for residents to make archeological discoveries in their own homes. Sometimes they discover entire rooms they didn’t know they had. Of course, these are usually found below ground – abandoned cellars branching off from, or sometimes below the main cellar. Some of the houses have three levels of cellar.
One wonders why our ancestors went to such trouble. Cellars are useful, of course, especially in a continental climate of hot summers and cold winters; but to keep on digging downwards must have required a huge effort in an age before digging machinery. If they needed more space, why didn’t they just build a bigger house out of town?
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The answer is that you had to be in town to benefit from the protection of city walls – and so when there was no more space at the surface, and houses had as many storeys as was feasible back then, the only other way was down.
In the global cities of the 21st century, the Middle Ages are back. Constrained not by city walls, but by property prices and planning restrictions, we’re digging down again.
In an article for the Guardian, Bradley L Garrett describes the land grab now taking place beneath our feet. Most notoriously, there’s the fashion for basement extensions in the posher part of central London:
“In London, a city with 150 years of trenching, digging and boring to its name, the chaos is reaching new depths. According to Newcastle University’s Global Urban Research Unit, more than 4,600 basements have been granted planning permission in the last decade – in just seven of London’s 32 boroughs…
“…Many of the basements contained cinemas, gymnasiums, pools, wine cellars and panic rooms. One even included plans for a subterranean beach with an accompanying waterfall.”
An especially weird aspect of these subterranean follies is that the diggers used to excavate them are often left behind. Having dug their way down into a confined space, the only way of getting them back up is by lifting them out with a crane – the costs and complications of which can be greater than buying a new digger. Therefore the last thing they do is dig their own graves to one side of the main development. That should be something for the archeologists of the future to puzzle over.
Technology, however, is moving on. Garrett mentions Elon Musk’s Boring Company – whose mission is to use tunnelling machines to create a 3D road network beneath Los Angeles. DARPA, the inventor of the internet, is also on the case:
“…the US Defense Advanced Research Projects Agency (Darpa) is currently funding a “subterranean challenge”, soliciting bids for techniques to enhance “situational awareness” of global underground spaces, with a $2m prize. The challenge is to create machines that can make their way through tunnel systems, urban undergrounds and natural caves.”
Another initiative worth a mention is the EU’s BADGER programme which aims to develop an autonomous burrowing robot.
If these and other technologies succeed in bringing down the costs of exploring and excavating the ground beneath us, then a new dimension of urban development will open up. We could afford more of what we already construct below ground e.g. road tunnels, car parks, sewers etc; and also some revolutionary applications. How about basement extensions for the masses? Or ubiquitous ducting for public utilities so that the roads never have to be dug up again?
And here’s another one: The reason why it’s so hot on some London underground tube lines is because the energy generated when the trains break has accumulated as heat in the clay surrounding the tunnels. In over a century of operation the ambient temperatures have gone from 14°C to more than 20°C. If we had an affordable and precise way of running a heat exchange network around these tunnels, we could extract the energy and use it to provide heating at the surface. Cool!
Of course, as Garrett points out, we’re going to need 3D maps of our poorly documented sub-cities and we’re going to have to properly sort out who owns what underground.
However, assuming that the technology and the regulation comes together, the space beneath us may turn out to be more significant than the space above us.