Sub-Urbia:The Colonization of
Underground Space

Fred Hapgood

It’s the mantra of every silver-tongued real-estate agent straining to close a deal: "They're not making any more land." But imagine if they were: suppose new land could be manufactured just like I-beams, bolts of cloth, or toothpaste. And what if this man-made space could be rolled out anywhere, even at the heart of the densest city, without displacing anyone?

Well, it can. The world’s cities may be overcrowded, and the suburbs that surround them choked by unchecked sprawl, but there’s a huge amount of undeveloped space, right at our feet, underground. How huge? Huge as in a hundred quadrillion cubic feet in the first mile under just the metropolitan areas in this country. You could fit twice the population of the United States in the first mile under metropolitan Los Angeles to a density of one million cubic feet per person. How's that compare with your floor-through?

One main problem has stood in the way of the industry sitting down to this Lucullian feast: Historically making underground space has always required lots of people. Two centuries after the industrial revolution came to manufacturing people were still drilling holes and carting out rock and building linings with hand tools. All these people drove costs up, and not just because they all needed to be paid. In the 1960's Howard Handewith, a contractor in Seattle, was part of a US National Commission that assessed the practicality of building an ultra high- speed transportation link under the Northeast corridor. What killed the project was the need to build escape shafts for the crew at every mile. "Nobody wanted to be in a position where if a situation came up they had to travel fifty miles to get out," Handewith recalls. Industrialization came slowly to the industry because the problem was genuinely hard and the market was too small to pay for the R&D required.

The news is that finally tunneling is close to being fully automated. Industrialization started in the 1950s when a mining engineer named James Robbins discovered that if you pushed a metal wheel with a sharp edge over a rock surface with enough pressure the rock under the wheel would shatter. A rotating array of wheels would penetrate deeper with every turn.

Initially the civil engineering community was slow to adopt the technology. At the best the first couple of generations of Tunnel Boring Machines (TBMs) could only cut speeds of only a few feet an hour and they would jam up over relatively modest (and common) geological transitions. Buying one meant a huge capital expense up front (TBMs cost several million). And finally, while drill and blast is inherently a batch process, tunnel boring is continuous. It works better if the machine is never turned off, which meant a whole new set of supporting systems had to be invented and marketed.

That has changed: today a modern TBM can slice corridors forty feet in diameter through almost any kind of geology, including sand, at rates of more than twenty feet an hour. It can run horizontally, vertically, in spirals. High-speed conveyors suck the tailings out of the hole, while a robotic rig automatically snaps lining segments in place inside the new surface, like huge Lego pieces. Drill and blast technique is almost as slick: a cutting edge blast-placing machine comes with sensors that measure all the aspects of the interaction between the drill and the rock and calculate the proper size and shape of the explosive charge. Even more impressive improvements are very close. An industry-specific XML dialect that has just been hammered out, the International Rock Excavation Data Exchange Standard, that will allow all these machines to talk with each other and with databases, simulators, and planning tools.

In a few years, five or maybe ten, the digging process should be entirely automated, run by people sitting on the surface in trailers, or even in offices a thousand miles away. (Many small tunnels are already dug this way.) You can get a feeling for where prices are now by looking at a couple of widely separated project price points: the 11.5 km Flam- Gudvangen road tunnel in Norway, which cost about $1.50/cu ft. and the Madrid Metro extension, which cost ten times more. (The differences in price have to do with differences in geology, the higher degree of finish required by a metro as compared with a highway, and the experience of the contractor.) The Madrid figure translates to $150/ sq ft., in conventional construction terminology, in which a square foot includes ten feet of height between stories. Further price declines will unleash a cascading wave of new applications: municipal, industrial, commercial, and finally, residential.

The first wave of projects, which we are in the middle of right now, are subway extensions, underground highway re-siting projects, and high-security depots for petrochemicals. These will pay for the further standardization and automation needed to permit big nation-linking Chunnel- type projects: such as Japan- Korea, China- Japan, and Taiwan- China in Asia, and Gibraltar and Bering Straits in the west.

The next step might be draw up plans for the ultimate TBM megaproject: the world subway. Maglev trains running through tunnels are the logical successor to air travel, at least between large cities. Unlike supersonic airplanes, trains in depressurized tunnels can run at many times the speed of sound without bothering residents with sonic booms or raising any of the land use issues that strangle airport development everywhere. Magnetic levitation means no rolling resistance and evacuated tunnels mean less air resistance. In a couple of decades we may see planners wrestling with the meaning of life in a society in which the major cities of the world are within a few hours’ commute of each other.

Anyone weighing the natural advantages of underground habitation -- low energy and maintenance costs, high security, zero conflict with plants and animals, virtually endless volumes to play with - - has to wonder whether humans are about to undergo another of those epic habitat shifts that have characterized the species since it first walked the valleys of East Africa. A few cities have one foot there already. Kansas has built 20 million square feet of industrial parks in old underground quarries under the city. Toronto and Montreal have extensive retail space beneath their downtowns. "It keeps the core dense and lively," says Jacques Besner, spokesman for Montreal Tourism, "which can be challenge in weather like ours." Commercial tenants like operating underground because the heat of the ambient Earth, usually around 57 degrees, keeps energy costs low.

One scenario might unfold like this: Perhaps by 2005 some under- urban highway projects will start to include parking lots. Where there are parking lots, malls will spring up. By 2008, developers might start to cater the needs of these retailers by offering warehouse space, then offices, and full-fledged industrial parks, and finally commercial hotels. In 2013 second-home residential developments might start to be marketed to international commuters as an alternative to hotels.

The low operating costs of underground space mean that competition among landlords can force rents down quite far. Whenever you have low rents, especially for large commercial spaces fall, artists show up, bringing with them their knack for converting discarded industrial and commercial spaces into highly desirable residential real estate. Sooner or later Yuppies will stumble onto the benefits of having hundreds of thousands of cubic feet at your their disposal. When they do it will seem unendurable to live without an Olympic sized swimming pool, a storage warehouse, jogging tracks, acres of hydroponics for fresh veggies year around, a ballroom the size of grand central terminal, a heavy ordinance shooting gallery, a grotto with a major waterfall, a paintball arena, a climbing crevasse worthy of Yosmite, a home theater for every member of the family, and so on.

Whether we will think of ourselves as "living underground" is harder to say. Moving functions off the surface will allow it to become much greener and more attractive, to be covered with conservatories, gardens, zoos, playing fields, parks, walkways, bicycle paths, and so on. We might end up spending more time, or anyway as much, outside, doing our business en plein air, going underground just to enjoy activities that require lots of space.

On the other extreme there will certainly be environmentalists who will refuse to go above ground at all. "To me the Earth’s surface is sacred," they will say, "would you walk on your Mother’s face?" Perhaps over time they will persuade us, or perhaps as we dig deeper the "commute" to and from the surface will grow increasingly inconvenient. It seems unlikely, even unthinkable, but then so would living in LA to one of those early Africans.