Why We Should Have Known Hyperloop Would Fail

Nature abhors a vacuum tube

Attention conservation notice: 16-minute read

There was a time, not that long ago, when we thought the future of transportation was to combine a rocket ship and a Thermos.

This turns out to have been a bad idea, but it's worth spending a bit of time exploring why it didn't seem that way at first, so that we can avoid mistakes like this in future.

What makes a rocket ship great is that, at least some of the time, it is travelling through a vacuum, and the lack of air resistance means that it can move at high speeds with limited power spent on propulsion. What makes a Thermos great is that, at least some of the time, it is sealed off from the outer environment by a vacuum, protecting and preserving its contents.

Hyperloop aimed to combine these functions. Passengers would be sealed into small pods, with a capacity of about 28 people at most. These pods would operate inside steel tubes which would contain mostly vacuum, with air pressure perhaps one one-thousandth of that at sea level. The pods would accelerate to nearly the speed of sound, so more than 1,000 kilometres per hour. The near-vacuum in which they operated would mean that once that speed was reached, minimal thrust would be necessary to keep it going. And that, in turn, meant that energy costs would be low and passengers would be comfortable, not pinned to their seats by the force of constant thrust.

(Acceleration and deceleration at the beginning and end of the ride would be costly, in both energy and passengers' comfort, but you can’t have everything.)

Speeds like that would be impressive. Had it worked, the Hyperloop could have taken passengers from Toronto to New York in about 45 minutes, or New York to Los Angeles in about four hours. That's competitive with commercial aircraft speeds, and especially so if—like high-speed rail—we imagine the Hyperloop would have travelled directly between city centres. But where it would really have shined would be middle distances.¹

Seattle to Vancouver in less than 15 minutes. New York to Washington, D.C. in 20 minutes; same time from Edmonton to Calgary. Toronto to Montreal in 35 minutes; and, indeed, San Francisco to Los Angeles as well. (This one's particularly relevant. More on that in a moment.)

But it was not to be: Virgin Hyperloop One, the most prominent Hyperloop company, ceased operations at the end of 2023. The technology is no longer being developed in any serious fashion by anyone. But for a decade or so, it dominated conversation about the future of intercity travel.

Why Hyperloop seemed so great

The obvious reference case to compare the Hyperloop to is high-speed rail (HSR). Both cases involve moving a vehicle in a dedicated right-of-way at high speeds. In fact, the earliest proponent of Hyperloop, Elon Musk, endorsed it specifically as better than HSR. Why?

Most obviously, Hyperloop would have been faster. California HSR is expected, at top speed, to travel no faster than 350 km/h, or less than a third as fast as Hyperloop.

For Hyperloop to exceed HSR speeds would have been enough to make the case. In transport, the two factors that consumers care about most are speed and cost, with other factors, like comfort or reliability, coming well behind. (If this wasn't true, commercial air travel would look very different than it does.) A 200% improvement in speed for Hyperloop over HSR would have been decisive. But Hyperloop, supposedly, would also have won the cost race, with a San-Francisco-to-Los-Angeles ticket to cost $20 USD in 2013 dollars.

Why so cheap? Supposedly, this was because of Hyperloop's cost profile. Like HSR, it would have a large capital cost to build: stations, rights-of-way, and trackage, in this case elevated or buried vacuum tubes, plus rolling stock. Unlike HSR, this rolling stock would be simpler and cheaper to build, because the real gains in speed would come from the infrastructure: the vacuum tubes would feature magnetic impellors, much like maglev trains today, to propel the passenger capsules forward. 

“Hyperloop Transporation [sic] Technologies - The Great Lakes Project3”, CC BY 2.0

That simplicity and inexpensiveness would in turn would mean that many more could be purchased and operated. Headways (that is, the time between departures) would be short, meaning that Hyperloop could serve many trips a day between destinations, or even many trips each hour. That frequency would satisfy all the latent demand for trips that Hyperloop could satisfy, and would indeed induce more, increasing revenue. Meanwhile, maintenance costs would be low. As long as the tubes maintained their vacuum, the system could continue to operate.

The rest was icing on the cake. No engines meant no noise pollution. All electric power meant green, sustainable, emissions-free operation. And all this while keeping the benefits of trains: downtown-to-downtown connection, fast boarding and disembarking, limited security requirements, and more. What's not to like?

As it turns out, plenty.