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Comment by ChuckMcM | Hacker News Reader

Good luck holding a vacuum under the ocean. I read stuff like this and I think, "Gee, I don't think these people have actually built anything." because if they had they would realize that if it costs $1M a foot too build subways [1] in cities with moderately skilled labor, its going to cost $10 - 25M/ft to build something like this. That's half a quadrillion dollars (448 trillion dollars). What sort or rate of return do you think you would need to make that feasible?

I'd love someone to actually do a credible cost analysis of an evacuated tunnel train. Unfortunately I don't think Oster did.

[1] http://secondavenuesagas.com/2010/01/14/the-costs-of-second-...

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It's probably more reasonable to compare the costs of this tunnel to undersea tunnels like the Seikan Tunnel (33 miles, $3.6 billion to build in 1988)[1] and the Chunnel (31 miles, $21 billion in 1994)[2].

1988 $3.6 billion = ~$7 billion today[3].

1994 $21 billion = ~ $32 billion today[4].

Put it altogether, the tunnel itself would be around $3.5 trillion[5]. Maglev + vacuum stuff would cost more.

(BTW, I love WolframAlpha for stuff like this.)

[1] http://en.wikipedia.org/wiki/Seikan_Tunnel

[2] http://www.engineering.com/Library/ArticlesPage/tabid/85/Art...

[3] http://www.wolframalpha.com/input/?i=%24US3.6+billion+1988+d...

[4] http://www.wolframalpha.com/input/?i=%24US21+billion+1994+do...

[5] http://www.wolframalpha.com/input/?i=%28%28%2432+billion%29%...

It really shouldn't be that bad. The cost is mainly due to it being in a dense city and having to deal with endless environmental (broad sense) concern.

A better comparison is an actual underwater tube: http://en.wikipedia.org/wiki/Transbay_Tube

3.6 miles cost about $1 billion in 2012 dollars. Closer to $55k/foot.

Don't get me wrong. This is still impossibly expensive even at that lower rate: $22 trillion.

Even at using costs of the propsed high speed rail in California ($80M/mile), nyc-london would cost $280 billion.

"Even at using costs of the propsed high speed rail in California ($80M/mile), nyc-london would cost $280 billion."

Which is roughly 1 / 14th the cost of the Iraq war. Not bad if you think about it.

It begs of a cost-study, I mean, I'd gladly pay 4x the current cost of an economy flight from NYC->London if I could take a train of equal comfort that only took an hour or two.

You think that's not too bad?

2006 revenues: $2440 billion

2012 revenues: $2660 billion

2006 spending: $2660 billion

2012 spending: $3790 billion

2013 spending: $3803 billion (Obama's proposed budget)

[Source: Wikipedia.]

Just think - we could do three or four megaprojects a year with a 2006-esque budget elsewhere plus those kinds of budget deficits.

Of course, as anyone in California is painfully aware, the high-speed rail project is a complete joke :) you'd need to trust that this one would do better.

Also, as an economics aside: In the private sector, a $280 billion project should hope to earn in the neighborhood of $11 billion a year in profit/savings in order to cover the cost of capital. This is, of course, after equipment maintenance, fuel/power, deprecation, labor, etc.

Of the $80M/mile - $70M is to buy the land and pay off objectors, $9M is security and fencing for the work site and $1M is to build the actual track.

The nice thing about a transatlantic tunnel is that crustecaeans can be bought off cheaply

> The nice thing about a transatlantic tunnel is that crustecaeans can be bought off cheaply

The various environmental organizations aren't going to be bought off cheaply.

This tech is far better for the environment than the air travel it would displace.

That's true, but it would be a while until this form of transport would be expansive enough to displace any significant amount of air travel. Don't get me wrong though.. im all for this development!

Since when did reason matter to these groups let alone trying to please all them at once.

Plus any operation at this scale will require all the security if not more of a normal one. It is just too big not to be a target for someone.

That's the advantage of a deep sea tunnel - it's tricky for even the most committed tree-hugger to do so 3km down!

They may be louder than rich people in cities, but I doubt it would be more expensive.

If you get the sierra club complaining publicly about the tunnel, you instantly have about half of the politicians in the country in favor of it.

Indeed, there's already a vacuum we already have above our heads that could be used for this purpose... i.e., suborbital space flight.

I can't imagine it'd be more expensive than tunneling 3000 miles under an ocean.

That's what I've been thinking as well. This might be an unintended consequence if SpaceX is able to reliably deploy the reusable rockets they are drawing today. It might actually require less energy to launch a passenger vehicle above the atmosphere and let it glide/freefall all the way to the destination than it does to push the same vehicle through the atmosphere. I haven't actually done any calculations, though. It would be interesting to see how much energy it would require per passenger to get such a vehicle to a suitable altitude and speed for intercontinental flight. For instance an aircraft powered with combustion engines, with booster rockets attached.

The disadvantage of your solution is the environment impact of such a transportation system. An electricity based solution seems to be much cleaner (especially if we imagine the same kind of traffic as the plane one today).

Couldn't you use electricity to separate hydrogen and oxygen from water, and then "burn" that in the rockets to produce water again?

> Couldn't you use electricity to separate hydrogen and oxygen from water, and then "burn" that in the rockets to produce water again?

How does the energy/pound and energy/CC compare to decent rocket fuel?

Liquid hydrogen/liquid oxygen is the most efficient chemical rocket fuel possible. Most famously used by the Space Shuttle Main Engines.

You can, but under current technology this is a lot less efficient (I remember hearing a 12% figure somewhere) than direct-drive electric motors.

I doubt it is a tunnel. I imagine it'd be more like this: http://en.wikipedia.org/wiki/Immersed_tube

(San Francisco's rail connection across the bay uses this technique)

At a fixed depth, so probably more like this: https://secure.wikimedia.org/wikipedia/en/wiki/Submerged_flo...

There'd be incredible pressures at the depths of the ocean floor. Look at that tiny submarine able to go down as far as the Titanic.

For varying hardnesses of vacuum, you can find a partial vaccum of 4 psi at 30,000 feet.

Which is enough to drop drag a lot, and still maintain lift in, say, commercially viable air transportation vehicles.

Lowest costs I've seen to LEO are about $1,000/lb. Suborbital flight isn't much lower than that, and we're still looking at something on the order of $10k - $1m per passenger at rates like that. Affordable to some, but (considering you've likely got a baggage, life support, and related allowance) pretty pricey all the same.

$10k is comparable to Concorde, as I recall. I consider that a very optimistic estimate.

A vacuum only weighs 1.28 grams less per litre than air. Since there are 1000 litres in a cubic meter, a 3x3x3 meter cube (approximation of a cross section of a unit of the tube) would contain 27000 litres whose air would weigh 76 lbs.

In other words you're talking about sinking 3 meters of tube that would weigh 76 fewer pounds than if there were air. This is probably a small effect compared to the weight of the strong metal casing that would need to surround such a vacuum.

So since we can sink normal air-filled subways quite normally (e.g. the BART in San Francisco) this must be a well-established technology.

It's not about vacuum being weightless. It's about vacuum being an active stress factor for the entire construction.

It will _want_ to collapse. It's not sitting there doing nothing.

Well I was responding to a specific poster who focused on a different issue. Steel tubes can easily withstand a vacuum... a round tube is an extremely strong structure. Sure the joints between pieces would be the harder part, especially with earthquakes and the like forcing flexibility.

Wouldn't they put the vacuum tube inside of a slightly larger tube?

Other countries with different building laws have very different costs. Say what you will about Spain, they can build subways or rail for one tenth as much as it costs in the US. French and British trains are also, I believe, much cheaper though not quite that much.

> It claims that it could “provide 50 times more transportation per kWh (kilowatt hour) than electric cars or trains,” that construction would cost a tenth of high-speed rail and a quarter of freeways

Who knows what this claim is based on, but it is there.

Daryl Oster's company has submitted proposals to Florida, at least, on building and maintaining a system such as this. I think part of the requirement for submitting such a proposal is at least a cursory cost analysis. Wikipedia reads a bit like the company wrote it itself, but:

The firm fixed bid for the 96-mile (154 km) Evacuated Tube Transport (ETT) system was $253M, this was less than one tenth of the cost of the bid by Global Rail Consortium to build electrified double track High Speed Rail for $2.6B. The bid by et3 contained letters of support by three entities in China to supply IP and key materials for the project. The engineering consultants hired by the authority did not dispute the validity of the et3 bid price or ETT technology, but recommended to eliminate the et3 bid from consideration for other reasons.[1]

This comment doesn't pass judgment on whether Daryl Oster is a patent troll or not, but that's also a discussion worth having.

[1]: http://en.wikipedia.org/wiki/Evacuated_Tube_Transport

Would love to see how they costed that out. Given that I don't know of a single engineering company that can build straight up light rail track for at $2.5M/mile even if you give them the land for free.

Edit: add this update --

Interestingly this link: http://www.freerepublic.com/focus/f-news/843626/posts claims that the ET3 bid was 1.2B$ which is $12.5M/mile which is a lot more credible (still low though since the surrounding infrastructure to keep the tube evacuated, the mag lev stuff, etc all add cost over regular fused rail electrified service (which California is considering for its fast rail) and that is looking closer to $25M/mile in the current state of the art)

A large chunk of the costs of projects like this is building the long flat tunnel/level ground over significant distances. The actual costs of building a moderate vacuum is not that significant. Where this project falls down is in the maintenance and safety side of things not the infrastructure to send the first train down the line.

Don't forget every 10m adds 1atm water pressure. Building a glass enclosed under sea walkway 30m down is not that much harder than building one 20m down and these projects are going to be using glass.

There are two problems here.

Firstly: As I see it, an evacuated tunnel at 20m is a very different proposition to a non-evacuated tunnel at 30m, even if the pressure difference is the same. Why? Well, your big problem is always going to be leaks. In an air-filled tunnel you can get away with microscopic cracks, no problem; you've got a small direct interface between water and air, and the surface tension of the water is enough to keep the water in place. It's very hard to force water through a really tiny crack. In a vacuum, however, surface tension goes away -- liquid water at an interface with vacuum will boil, and all of a sudden you've got water vapour filling your nice evacuated tube through every microscopic crack in its five thousand mile length. Nasty. Clearly the joined-concrete construction used for the Transbay Tube isn't going to be sufficient.

Secondly: unfortunately the Atlantic Ocean isn't 20m deep, or 30m deep, or even 40m deep like the deepest point of the Transbay Tube. It's several kilometers deep.

Is there some reason that sandwiching air between the evacuated tube and the water wouldn't work? Granted it would add to the cost.

The ocean depth point is interesting. The article says "engineers would tether the tunnel at a fixed depth." I take this to mean tethering to the bottom and relying on buoyancy to keep the tunnel floating at the right depth, which presumably could be 30m or so.

>Is there some reason that sandwiching air between the evacuated tube and the water wouldn't work?

Yep, because now you've just got your air rushing into the vacuum through the cracks, instead of water.

Even if you could get it to be neutrally bouyant at 30m (realistic estimate? dunno) you're now stuck with a tube, five thousand miles long, floating free in the ocean and anchored only to the bottom. Even neutrally bouyant, there'd have to be huge strains on the joints due to ocean currents, plus presumably some up-and-down forces as the season changes the water temperature and... heck, even a whale headbutting such a flimsy structure sounds like a disaster waiting to happen. And remember, you can't afford to get any imperfections in your tube or it'll leak -- that probably eliminates anything you might have used to build in a bit of flexibility.

>Yep, because now you've just got your air rushing into the vacuum through the cracks, instead of water.

Fair enough. I imagine there's a trade-off between the quality of the tunnel materials and the number of pumps needed along the way, assuming an imperfect vacuum is good enough.

I'd be worried about flexibility too. Skyscrapers do pretty well in high winds and earthquakes, so I'm not completely convinced that a similar effect isn't possible with an underwater tube. Any bending would have to be extremely gradual, though, if there's any hope of shooting something through it at high speeds. I agree that glass isn't going to cut it.

Some kind of gel between the layers perhaps?

> a glass enclosed under sea walkway 30m down is not that much harder than building one 20m down

It's 50% harder.

What pressure are the passengers exposed to?

I ask because 1 hour @ 4 atmospheres of 80% N2/20% O2 is risking decompression illness. (Yes, 4 - you've got 1 atmosphere at sea level.) You can reduce that risk by increasing the O2 percentage but if you do that too much, you're risking O2 toxicity.

How the hell does light rail track cost $2.5M/mile? How did people build railroad tracks back in the days of horses and buggys?

Slave labor and "slave" labor.

Slave labor was too expensive to use because you risked losing your valuable capital. Instead new immigrants were used such as Irish (East Coast) or Chinese (West Coast).

Slave labour was used sometimes, e.g. the Thailand-Burma railway.

http://en.wikipedia.org/wiki/Burma_Railway

Five hundred men died for every mile of track laid, but hey, they had too many prisoners anyway!

That's the "slave" labor.

I feel that most of the cost is for tunneling and the difficulties of working in such a space as a subway system. as for normal railroads, a quick googling shows that the cost is much more conservative, with a 1995 estimate[1] stating about $250,000 per mile to rehabilitate an existing railroad.

[1] http://tacnet.missouri.org/history/railroads/rrcosts.html

Light rail is above ground, often operating alongside street traffic.

That is a great question, I wish I could reasonably answer it. I'm a big fan of rail, and while San Jose was celebrating their first 4 miles of light rail (in just 10 years from the start of the project!) I was looking that the marker in the Sacramento Rail museum (recommended) commemorating the laying of 10 miles of the Union Pacific rail line in one day.

Part of it is that some folks really hate rail, so much so that they will continually sue anyone who is working to build it. They will argue wildlife endangerment, habitat destruction, cancer risk, suicide risk, traffic risk, earthquake/disaster risk, global epidemic risk, job preservation/creation/destruction risk, you name it. Anything to get back in court and have a judge temporarily suspend work. Because you hire someone to work on a project, and they can't because of some court order, you still have to pay them. So what happens is these projects have 'burn rates' (which is the cost of renting equipment (or depreciating it if you own it) and labor and materials (some of which degrade over time if not used)) and then you have 'able to work' days. Actual work days might be 90 for a mile of track, but time actually passed is like a year. So the other 275 days people sat on their hands while expensive lawyers argued to get work restarted.

Its one of the things I bring up at town hall meetings with politicians. The tax payer, and the 'NIMBY' [1] folks, fight a very asymmetric kind of warfare. No court challenges until funds are committed, and then six. You need look no further than the maneuvering around the California High Speed Rail project to see it play out in all of its ugliness.

[1] NIMBY -acronym Not In My Back Yard for people who are opposed to any new infrastructure near where they live.

Isn't this part of why rail is a lot easier to do in Europe? My understanding is that it is a lot harder to sue over stuff like this there. Maybe someone familiar with Europe's rail situation can chime in.

Passenger rail is excellent in Europe, but rail freight is atrocious.

It's the opposite in the USA.

The Economist had an interesting report on the reasons for the difference: http://www.economist.com/node/16636101

The process is definitely different at least in the smaller countries. In Denmark, when the Copenhagen metro expansion was agreed on by the government, the plans were passed as a law through the national parliament. Therefore, everything in it became by definition legal, superseding any contrary legislation, unless it violated the constitution.

The U.S. instead tends to work on a model where the legislature passes general rules, and then agencies administer the rules in specific cases. So, for example, a specific rail plan is proposed pursuant to a piece of legislation, but the plan is not itself a piece of legislation superseding others. That leaves it open to all sorts of lawsuits alleging that it didn't comply with the legislation that applies to it.

Great response.

>San Jose was celebrating their first 4 miles of light rail (in just 10 years from the start of the project!)

> Actual work days might be 90 for a mile of track, but time actually passed is like a year

So currently, San Jose can build 0.25 mi/year. Optimistically, with no lawsuits, their actual work days could increase to say, 225 days/year, which is 2.5x faster. So we're up to say, 0.66 mi/year, which still sounds way too low. What are the other bottlenecks?

Well one of my political suggestions to 'even' the playing field was to create a certification date for a project after which no lawsuits could be brought against it. This would give the project planners a way to budget the years of litigation, and once they were certified they could start and continue until they were finished without interruption (except for the usuals, weather, labor disputes, and material shortages).

I've gotten some positive feedback for that but have yet to find someone willing to actually submit it in a bill.

Haven't you just proven that your initial post above is irrelevant to an undersea rail system?

I'm not saying an undersea rail system is practical or smart. I'm just asking the relevance of your comparisons to US urban construction costs to begin with.

As a suggestion, a different tone might make your post seem more useful and less trollish. For example "An undersea tunnel will require serious construction breakthroughs to be practical. As a comparison, today's costs...". That would be a lot more constructive than attacking the people behind the article.

Great feedback, thanks. The conversation wandered a bit, and while I don't think of my style as trollish I can certainly see how my emotion on rail interferes with my communication.

My initial point is a prima facie argument, the proposal is impractical by inspection. I certainly stand by that assertion, but as part of the supporting argument we've been discussing land based construction with the implicit, albeit not as well supported, stipulation that sea based construction would always be more expensive than land based.

An interesting way to approach the problem would be to outline the design space in terms of operation cost, development cost, and rate of return and see what sort of solutions, if any, might fit inside that box.

What conceivable technologies might make it practical someday?

How can we get back to a society that is able to engage in large scale projects again? Look at the rapid low-cost subway construction in China today.

I think you're a super smart guy with really broad interests, experience, and knowledge. I think you could make the impossible happen if you applied yourself to it.

They built awfully bad ones, by today's standards. Rails weren't prestretched and welded together. Instead, they left gaps between rails to cater for temperature differences (http://en.wikipedia.org/wiki/Track_(rail_transport)#Joining_...)

Modern trains also are heavier and accelerate and decelerate faster than the trains you see in westerns. Both mean that they exert greater forces on the rails.

Finally, safety standards are way higher. That means that material must be of higher quality and tested better, both at the factory and after installation.

There is also the issue that the FRA in the US makes trains considerably heavier than equivalents in the rest of the world. http://www.ebbc.org/rail/fra.html

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