The first thing that struck me when I readElon Musk 's plan for a sort of high-speed pneumatic tube system between Los Angeles and San Francisco, was the urge to say "Gee whiz!" There's not a lot of novelty in transportation these days: Elon Musk is thought of as an incredible innovator because he managed to create a marketable car that runs on an electric motor rather than gasoline. I'm ready to scrap California's high-speed rail project and build this hyperloop thing instead just because, wow, cool! Might it be a massive waste of government funds? Possibly, but probably not as wasteful as the high-speed rail project. And I adhere to the basic principle that if the government is going to fritter away our money on infrastructure projects, those projects should be as nifty and futuristic as possible.
But I suppose that we can't actually authorize infrastructure projects without examining the basic costs and benefits (though if you'll look at the California plan, you'll see they came pretty close). So why might we want to build a hyperloop, instead of a train or nothing at all?
- It's environmentally friendly: Musk says that the entire thing can be powered with solar cells mounted on top of the hyperloop. That's because the 28-passenger pods are travelling in a low-pressure environment, where they don't have to muster so much energy to overcome wind resistance.
- It's fast: Because of the aforementioned lack of wind resistance, the pods can move at upwards of 700 miles per hour. A trip between L.A. and San Francisco could be completed in well under an hour. This is not only faster than high-speed rail, it's also faster than an airplane.
- It's safe: It's basically impossible to have one of the most common kinds of plane crashes because the pods aren't generating their own motion; they're being accelerated from outside. You can imagine a line of people tossing balls from one to the other, which isn't a good explanation of the physics, but gives you a feel for the thing. A ball does not slow down on its own in mid-toss, so you don't have the problem where one pod stops, and the one behind it crashes into it. If the tube pressurizes, all the pods slow down. As far as I can tell, even a terrorist attack probably couldn't kill much more than the people in one pod -- which is terrible, of course, but far less than the casualties from a plane or train crash.
- It can use existing rights-of-way for highways. Construction will be necessary for stations, some tunneling and to straighten out curves. But if the California Department of Transportation wanted to build this thing -- a big if -- it could minimize the need for new land acquisitions.
- It's in the air, which means that other land acquisition may be easier. Farmers are likely to be much more open to your running some pylons through their land.
- It's cheaper than high-speed rail. Even if Musk's estimates of the land acquisition costs are off by a factor of ten, this would still be much, much cheaper than the rail boondoggle. The operating costs are also supposed to be low -- low enough to allow a ticket cost of $20-40.
- Cars can depart every two minutes, according to Musk. (He suggests once every 30 seconds at peak periods, but this seems optimistic to me, simply because I don't see how you load and seatbelt 28 passengers every 30 seconds.) This means minimal waiting around, and you probably don't have to book assigned seats; just show up and go.
So what are the downsides?
- As I believe I mentioned, it's going to be more expensive than Musk is projecting. Even if you assume that he will get the right-of-way along the highways, his estimates of land acquisition costs seem ludicrously low.
- It's a fixed route. The great advantage of planes is that you just need an airstrip at both ends; if one route doesn't have enough demand, you just move the plane to another. The tube requires a large capital investment before you know that you'll have passengers, and if you get the route wrong, you're stuck.
- The throughput is limited by the capacity of the tube. Essentially, the hyperloop is a tunnel that goes for hundreds of miles. Once you hit capacity, that's it. Presumably, you can build another tube, but this will be about as expensive as building the first.
- It's not clear to me whether you can have intermediate stops. The tube will go from L.A. to San Francisco -- and only from L.A. to San Francisco. That means no development along this corridor you're building, and limits the potential passengers.
- Where will the hyperloop terminate? It will be difficult to get into downtown. I'm more sanguine than Alexis Madrigal about this: It's at least theoretically possible to run the thing above the streets, or even above low houses. But this will be complicated and controversial -- and expensive. Of course, it doesn't have to go into downtown; it could still be a good airport substitute even if it's quite a ways from the central city. But it would be better if it terminated in the middle of the highest density areas.
- It is going to trigger fierce resistance from a lot of rail buffs. They're heavily invested in California's high-speed train. This threatens that dream.
Overall, I hope someone builds this, as it's potentially revolutionary. But as whiz-bang as the hyperloop is, I'm not sure it's powerful enough to overcome the fearsome obstacles to its own existence.
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Megan McArdle at email@example.com