What Happened to Hovertrains? (2018) [video] | Hacker News Reader

What Happened to Hovertrains? (2018) [video]

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@1:10 Trains in Japan were initially only running at speeds up to 130 mph in 1964.

Over half a century ago the world had bullet trains. I guess when we had 200 million Americans we didn’t think it was worth the effort. Now with an extra 130 million people, it’s too difficult and expensive.

it will be more interesting if we ever get down the costs of energy, then we can focus on really fast tech. its also worth noting that trains between philadelphia and nyc (Acela Express) go ~135-165 mph.

if it takes 6 hours and ~ 450$ to get from nyc to sf, it would be more revolutionary to reduce the cost by 50% than than cut the time in half I think.

Why are train tickets so expensive? I get long distances but it always seemed so expensive to me.

For example I could go between Toronto-MTL by bus for $20-30 but by train its $100-120.

Many reasons, but for a start, the roads are much more subsidized than the rails are.

Freight pays better than passengers. They don't want passengers. They might be obligated to maintain passenger service.

It's a good question, but having seen bus upkeep compared to train upkeep, it seems like it takes a lot more labor to keep a train moving.

Might have something to do with how expensive replacement parts are. Bus engines are of course highly commoditized, where as a lot of trainsets are one-off manufactures, maybe replacement parts have to be special ordered? Just speculating.

I'm guessing the average speed is lower due to sharp curves?

That and just the condition of the tracks. Same problem as the NYC subway -- everything is 100 years old, but when can you stop train service to replace it?

In 1947 the US introduced a speed limit of 79mph for trains without automated train control (ATC) systems after a Chicago commuter train crash killed 45 people. [1]

Over 30,000 people were killed in car accidents that same year [2]

The reason ATC is not installed more widely is a matter of debate (besides, of course, the expense). There's a general sense that freight companies just like having the right of way to themselves, and making passenger trains slow and expensive is a good way to achieve this. There's even a conspiracy theory that Amtrak was instituted for this very purpose -- to have a government subsidized company no one could compete with, but that no one would want to ride either... (I could go digging for the newspaper clip, I just saw this on an Amtrak forum once...)

[1] https://en.wikipedia.org/wiki/Naperville_train_disaster [2] https://en.wikipedia.org/wiki/Motor_vehicle_fatality_rate_in...

It seems to me the fundamental inescapable problem with hovertrains was simple: they’re loud. Sound is a pressure wave, hovercraft require high pressures; therefore, they are noisy. Even if you solved momentum drag, track maintenance, and everything else, nobody will let you build it near their house.

(Maybe a maglev train could hover only at low speeds inside a station. Maglev works better for moving trains rather than stationary ones. But then it’s not a hovertrain.)

It's not at all obvious to me that the noise from the pressure levitation system of a hovertrain is louder than the noise from drag, which the hovertrain and maglev both share. Do you have a link?

TBH, I would've expected a Maglev train to "touch down" in a station, at least that is what I would do if I were to have designed it...

Anyone here ever rode on the Maglev in China can provide more details?

They can touch down/"take off" while stationary (not sure if they do it while stopping in stations), but don't have wheels, so they have to hover to move at all. If both sides of the maglev system fail, they have skids designed to slow them at a safe rate, but that's emergency use only.

Just an engineering aside, you'd probably want braces to engage the train rather than the train to lower. If it lowers you have to raise it before it starts again which would require extra energy and substantial force.

I think a kind of "landing gear" would be preferable, as its operation could be station-independent, which in turn centralizes maintenance, therefore reducing running costs.

AFAIK, there currently isn't an actual Maglev network in operation (just point-to-point - no traffic, no stops), but if there would be, I think it's easier to have any train be able to stop anywhere on the track than to have it stop at specific locations only.

But other than that, yes, you're definitely right that any change of elevation of the entire train should be avoided as much as possible.

EDIT: I just realized, my last paragraph isn't necessarily true either, i.e. compare the situation to start-stop-sytems on cars, there's a sweet spot in efficiency, when turning off the engine and starting it would cost more than letting it run all the time.

Japan Rail’s solution to the noise problem was to bore a tunnel hundreds of kilometers from Tokyo to Osaka via Nagoya

Looking at the Chuo Shinkansen, it seems that the tunnel allowed the train to turn less through the mountains, considering that turning is pretty hard to do at 500 kph! Also:

>JR Central aims to begin commercial service between Tokyo and Nagoya in 2027, with the Nagoya–Osaka section originally planned to be completed by 2045.[5] The government is however planning to support a speed up of the timeline for the construction of the Osaka section by up to 8 years to 2037 with additional funds.[6]

Imagine a US government construction project being finished ahead of schedule.

One thing I've been wondering is whether is possible to power a ground effect vehicle from overhead wires. That would sort of be like a hover train. The "tracks" would be cheap to build. Just need to compact the ground to a smooth surface.

San Francisco has this. Buses are powered by overhead wires. (because electrified tracks would kill pedestrians)

Lots of places have that, definitely almost nobody has ground-effect vehicles (which would satisfy the 'hover' bit): https://en.wikipedia.org/wiki/Ground-effect_vehicle

The need to constantly produce lift would probably consume a lot of energy.

I think solar energy is enough, at least for small prototypes.

Lift-induced drag goes down with the square of velocity. At high speed, the need to stay aloft doesn't cost you that much.

They will build (my perception) a hyperloop/maglev train between St. Louis and Kansas City. https://www.stlmag.com/news/missouri-could-be-getting-a-hype...

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