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Technological change, part 1: Tunnel building

There's been a fair amount of discussion recently about future technology and transportation. How will technology affect the way our cities look and operate?

Tunnel boring machine. Photo by SqueakyMarmot on Flickr.

Today, heavy rail is extremely expensive to build. But by not having to compete with traffic, it is faster and more reliable than other modes of transit. Light rail is pricier than buses but carry more people and generate more investment.

Will it always be that way? I believe that one day we'll see automated construction machines that can much more cheaply build a tunnel. We already bore tunnels by machine, instead of blasting by hand as the builders of subways did in the early 1900s. Unlike, say, flying cars or better batteries, there's no law of physics that says we can't automate the rest.

Computerized systems could block off a work site, relocate utilities, build the tunnel walls, and package up the debris for removal. It's just a matter of time and engineering. Plus, underground construction has obvious defense benefits. DARPA should start funding studies into automated tunnel boring.

What will happen if, in the future, we can build tunnels for a fraction the cost today? We could put subways anywhere the ridership would justify the ongoing operating costs (maybe something like this). Heavy rail out to more distant town centers wouldn't be such a boondoggle.

Of course, if it's cheaper to build subways, it's also cheaper to build underground freeways as well. With gas prices what they are, I'd hope we wouldn't be so foolish, though we'd probably end up with some of each.

Gas prices could radically change with technology as well. Say, a giant solar station in orbit? To me, creating completely new sources of energy is less immediately plausible than construction robots. We already build things with robots (like cars), and the history of computation is a steady march toward automating more tasks that we already do. An orbital solar station or some other major source of cheap power is a whole different undertaking, but who knows?

David Alpert is the founder of Greater Greater Washington and its board president. He worked as a Product Manager for Google for six years and has lived in the Boston, San Francisco, and New York metro areas in addition to Washington, DC. He now lives with his wife and two children in Dupont Circle. 


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Robots would be great, but we need a lot of things to happen to drive costs down. If we're talking infill, it's going to be expensive b/c of the complexities involved in operating in a dense area. If we can automate the construction, take up less space, operate 24/7 and somehow make the process of engineering, studying, etc. quicker and less expensive, than it would be great. But something tells me the political gridlock will always be there.

by Vik on Aug 21, 2008 2:15 pm • linkreport

Robots like Wall-E? The kid fell asleep but I enjoyed the animation and story, even if it was a bit slow. I love the venture into scifi for envisioning transit solutions in the future. Thanks. Isn't this the technology used for the Chunnel?

by Bianchi on Aug 21, 2008 2:22 pm • linkreport



sorry. :)

by Alex B. on Aug 21, 2008 2:23 pm • linkreport

Yes the cost of labor may go down, but the cost of material almost always goes up.

by RJ on Aug 21, 2008 2:34 pm • linkreport

Why does it have to be tunnels? Why wouldn't elevated railways be better?

You don't have to worry about drainage, air ventilation, boring holes under existing cities. You can use the roadways that already exist for paths. If the problem with them is that they're an eye-sore, then why not work on that and make trains and tracks that aren't ugly?

by chiggins on Aug 21, 2008 3:22 pm • linkreport


Why does it have to be tunnels? Why wouldn't elevated railways be better?

Noise, blocked out sunlight, big support columns, unusable/reduced land value underneath or nearby. Plus they're not necessarily any cheaper to build than tunnels, maybe even more expensive if automated boring technology does get better.

In that regard, it seems like a lot of the costs are not so much labor, but a general lack of experience and development of the technology, at least with large bore tunnels. There are only a handful of machines and personnel in the world, and even fewer projects. A (possibly non-representative) engineering document I read on the Silver line was a mass of uncertainties about rock and soil types, tunneling speed, etc.

A national commitment to invest in a significant number of new subway lines around the country might spur development and start pushing down costs in a hurry.

by jack lecou on Aug 21, 2008 3:50 pm • linkreport

Hopefully this fixes it. The whole everything-in-italics thing was bugging me.

by Mario on Aug 21, 2008 3:51 pm • linkreport

As a matter of fact, I was just poking around the code base to figure out the best way to fix the italics problem. But it looks like Jack beat you to it, Mario :)

by David Alpert on Aug 21, 2008 3:53 pm • linkreport

I fail to see how with gas price what they are would lead to us being foolish if we build underground freeways. I would think the foolishness or appropriateness of building an underground freeway would be dependent on other factors. Generally, I prefer underground freeways to at grade or elevated freeways, anyway. At the same time I'm generally opposed to building a freeway if it cannot be financed through tolls as that means that there is not enough demand for it to justify its construction. The vast majority of the time, undergound freeways (and other tunneled freeways) cannot meet their construction costs through tolls alone, so that means the money to build would probably be best used on other transportation projects.

by Mario on Aug 21, 2008 4:08 pm • linkreport

Fixed the italics... by just editing Alex's comment. A better solution will have to wait until I have more time to do it.

by David Alpert on Aug 21, 2008 4:13 pm • linkreport

Also, freeways and heavy rail are not the only things you could put in tunnels. You can also have light rail, buses, and/or streetcars running in tunnels. Most likely, in that case, you'd be running these only partly in a tunnel and partly at grade. You'd most likely also be running multiple lines within such a tunnel which then spread out into multiple surface lines. That's what they do in San Francisco, Seattle, and Boston (which actually has both an LRT and a BRT subway).

by Mario on Aug 21, 2008 4:17 pm • linkreport

Sandhogs already use drilling machinery in the actual excavation of tunnels. But there is a lot more to building a rail-suitable tunnel, including the engineering and planning, the relocation of the numerous utility networks that are buried under all urban and suburban streets, the construction of forms and pouring of concrete, and the construction of the electrical and ventilation systems. All of that requires highly-trained human beings from a multitude of disciplines and that is not going to change anytime soon.

Adam Pagnucco, Carpenters Union

by Adam Pagnucco on Aug 22, 2008 11:32 am • linkreport

Noise, blocked out sunlight, big support columns, unusable/reduced land value underneath or nearby. Plus they're not necessarily any cheaper to build than tunnels, maybe even more expensive if automated boring technology does get better.

Noise seems like it'd be a engineering issue, there's no reason they have to sound like Chicago's. Blocked out sunlight and big supports? In a city, where there's already buildings? Really, that's a problem? And if we're building them on current street paths, I would think that would be increasing utilization of already existing infrastructure? And "might be more expensive if boring gets cheaper" suggests that they are cheaper now.

I find it hard to believe that running enormous boring machines underground, building rail beds and/or highways and the systems required to support having thousands of people down there for long periods of time, and building stations that require entry mechanisms into these caverns and 24 hour lighting is more efficient and desirable than, say, developing a good looking and reasonably quiet rail system that utilizes street routes already in place.

But I'm also not anything close to an expert on these issues, have any links or references to anything I can read to get caught up on the issues you mentioned?


by chiggins on Aug 22, 2008 2:05 pm • linkreport

As a side note: Googling 'Expellitalicus' returns exactly one result, this page. Awesome.

by chiggins on Aug 22, 2008 2:07 pm • linkreport

I can't see tunneling equipment that maintains itself. Tunnels are already dug by huge, complicated machines with very little manual labor (the salary of the guy who drives the tunneling machine that's digging the tunnels under NYC now must be less than 0.1% of the project cost). Automation can't really reduce those costs significantly further, I think.

by David desJardins on Aug 24, 2008 1:02 am • linkreport

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