They were invented decades ago.

They have fewer moving parts than wheelbois.

They require less maintenance.

There’s obviously some bottleneck in expanding maglev technology, but what is it?

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52 points

The same reason supersonic passenger jets are rare.

The extra speed comes with a massive increase in costs.

Travel 30% faster than high speed rail for 10-20 times the cost.

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13 points

Is the claim about “10-20 times the cost” true? The internet says Shanghai maglev cost $1.33 billion for 30.5 km, i.e. less than $44 million/km. Compare https://transitcosts.com/new-data/ or https://transitcosts.com/high-speed-rail-preliminary-data-analysis/

Secondly, if it is true, why would it be true? Why would it be more expensive to build something with fewer moving parts?

Supersonic passeenger jets require more energy. Maglev trains require less energy.

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22 points

all the other complex and important factors aside, air restistance is a formula of speed squared. Meaning for example if you bump speed up by 40% you double air resistance, and therefore double the energy cost of transport.

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13 points

Isn’t that only applicable for identical trains? For sake argument, if you had two identical trains designed with poor aerodynamics, one at 100mph and one at 140mph then you can double the energy cost. But if you take two different trains with one designed to be more aerodynamic, at the same speed they wouldn’t have the same energy cost as the second has a better profile?

Plus theres less friction from needing to be on a rail.

So I think saying its double the cost of transport is too simplistic to be meaningful in this discussion

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17 points

Maglev requires superconductors to work. They must be cooled to just a few degrees above absolute zero (typically ~ -270 celsius) and if they ever warm up beyond their critical temperature, catastrophic failure is the result. (this is called quenching which can destroy the superconductor permanently) So not only can you only drive maglev trains (which are expensive themselves) on maglev track and can only drive mag lev trains on maglev track, its far more expensive to build and maintain superconducting infrastructure than it is to lay down some steel rails. Maglev trains are used because the only friction that they experience is from air resistance. Theyre much faster than normal trains but it takes a lot of energy to keep the superconductor that makes them work cool, costs a lot more to build and requires a lot of electricity to get them up to speed. (They can use regenerative braking to recover much of this but its still an energy intensive process)

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0 points

fwiw LN superconductors that operate at much higher temperatures are already being built https://eandt.theiet.org/content/articles/2021/01/superconducting-maglev-train-unveiled-in-china/

Also, China manages to charge only $8/ticket for the shanghai maglev, so evidently it can be done cost effectively.

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6 points

Japan is in the late stages of developing a maglev section of the Shinkansen. It has liquid helium cooling for semiconductors and lots of considerations to make sure the cabin and surroundings aren’t exposed to very strong magnetic fields. It’s just more expensive to do all that.

After Japan rolls this out and works out the kinks, it might get cheaper since a lot of they’ve done a lot of the development.

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2 points

Maglev’s top speed record is just 5% faster than conventional train speed record. Thus if Maglev is more than 5% more expensive, then it doesn’t make any sense to build them.

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1 point

Speed records aren’t usually representative of regular use top speeds, are they?

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