Why are maglev trains still rare?

If you introduce a new rail type into your rail network you can't use your existing fleet of trains on that section reducing the ROI on that train engine or carriage. Also, any train you purchase for the new rail type will only ever work on that system lowering their profitability in the long term.
- A million times this. Mag-lev only works for either super dense routes where the added cost as you describe can be displaced by the immense value add of shorter and generally more comfortable travel. Or in nations that can force through decisions from the top down, such that cost becomes almost a non-factor like China. Rail in general across the western world is a weird mix of nationalized and privately owned companies and operators, such that introducing mag-lev with the intent to replace conventional rail would require compensation to the private companies who have invested billions in the current infrastructure else they simply won't be part of the new one, with all the issues that entail.
  From an environmental standpoint it's also really hard to see an ROI in scrapping something that works in favor of mining, constructing and spending intense amounts of energy in all forms to build something better but only moderately so. The biggest improvement is moving from trucks to (electric) train for freight, going from electric train to mag-lev is only slightly better so the ROI just won't be there.
  
  I would suspect it would be complex to design mag-lev for all the various types of loads trains for be subject to. Wheels are fairly versatile and have a wide range of loads.
- Also the fact that 'less moving parts' doesn't mean lower complexity or maintenance cost. Train wheels are a very robust and efficienct mechanism and most train designs are not being limited by them.
  
  Very robust because they have 300 years of research, innovation, materials science and manufacturing in them. Making them incredibly stellar, well understood, damn near perfect technology for what they do.
- There are some concepts for hybrid maglev-rail tracks that would at least solve the first point, similar to how rail was electrified over time. It would still be very expensive though.
  Recent demonstration https://www.youtube.com/watch?v=CQOEP7_euXQ
  
  woah this is awesome!
  maglevs need classical wheel systems anyway because there might be a power outage, so simply having wheels that are compatible with the local rail system is a brilliant idea.
  add in a tiny propulsion system so they can use the normal tracks at low speed without the help of the maglev tracks and you can sort of blend the two systems together in critical locations like switches and train stations.
  
  Here is an alternative Piped link(s): https://piped.video/watch?v=CQOEP7_euXQ
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- Not to defend capitalism in general, but it’s really good at answering these sort of “is it worth the cost?” aquestions. The whole point is to allocate scarce resources efficiently; the problem is that it assumes nobody is a scumbag and all the costs are accounted for.
  
  It isn't. Most decision makers of capitalism are very unaware of science. You'd know this if you work in research. The ideas that see light of day do so not because they're good in any quantifiable sense. It is because they convince the capitalists. This can be affected by so many things that aren't merit or even cost based.
  Some things make sense from a cost perspective, but not a profitability perspective. Profit isn't just about cost. There's margins, competition, longevity, etc. Something can be of moderate costs, but if the margins are too low or it is too long term or a project, it is of low value to capitalists.
  
  The current, dominant form of capitalism isn't and doesn't, though. It maximizes short-term profits and ignores all other medium and long-term costs. The efficient allocation of scarce resources doesn't happen when inefficient allocation yields greater short-term profit. The stock market ensures that high short-term yields with lower total returns will be favored over the inverse. In particular, it emphasizes competition over cooperation, which is more resource wasteful for the gestalt.
- What kind of benefits are there to maglev trains that are not cost related?
  
  They're faster and more comfortable than traditional rail. They could help to reduce air and vehicle travel
  
  Better acceleration, steeper inclines, tighter curves at same speed, better ride quality and less wear. As someone has mentioned below, normal trains could go a lot faster than they do in practice, because the ride quality, wear and wind resistance get atrocious, and the tracks need to be exceptionally straight. Making a maglev go fast is more feasible, though you still have the wind resistance issue obviously.
- Where are all the maglev trains in non-capitalist countries? Sooner or later, in any system, someone has to do a cost benefit analysis and decide whether it's worth it. It's not just about profitability. There are plenty of situations in the US where something is unprofitable but still funded because the benefit is worth it.
  
  Dude, without capitalism we’d be living in flying maglev RVs on mars with free robot labour bro
  
  Three of the six currently operating maglevs are in communist china
- "MVP" stands for "minimum viable product".
- It's basically evolution. It's not that we don't get the best things, it's that when something evolves traits that require more energy than they are worth, they inevitably die out. I'm reminded of the film The Man in the White Suit.
  It'd be nice to always have the "best" things, but the "energy" to support them has to come from somewhere.
  
  But unfortunately the mechanism that is dictating which traits are carried through and which are left to die out, is capitalism. Not just that, but short sighted capitalism.
  I'm not saying maglev is the be all and end all, I'm just saying that this "evolution" is sort of (extremely) fucked.

construction is Hella pricey
there are few maglev manufacturers, allowing vendor locking and exacerbating the first point
they must be built grade-separate, which can complicate route planning
they are incompatible with existing rail tech, which results in having to build new, expensive infrastructure for 100% of your route, further exacerbating the first point
their switches are slow, limiting capacity
Ultimately, their competition is regular trains, which are simpler, more tolerant to buying from multiple manufacturers, still significantly more efficient and faster than anything roadborne, able to switch over the course of seconds instead of minutes, able to interoperate with different tiers of intensity and speed, able to be built at grade, cheaper and having the better part of two hundred years of technological refinement behind it. Ultimately, maglev has specific, niche advantages that make it a hard sell for any system that already has regular rail.
- What is grade-separate
  
  They can't cross any other tracks/roads. I.e. everything else must go above/below it.
- A lot of these arguments apply to high speed train. In France a completely separate line was build between Paris and Marseille for the TGV To reach its peak speed without being delayed by lines that stop at every station.
  The problem is investment and shitty companies holding these technologies IMO.
  
  To compare our bullet points for maglev and high speed & conventional rail:
  there's a big step in price between "a railway line built to millimetre precision" and "a completely new type of infrastructure that may or may not need superconductors to work"
  there are way more manufacturers for components of high speed rail. For rolling stock there 4 in Europe alone, plus more in Japan, South Korea and China. As for signalling, it depends on the underlying tech. And if we follow the current European tech standard, that encompasses a standard... That is made by multiple manufacturers, and where their systems are operationally compatible.
  for one, high speed rail is still rail, so building at grade & laying them on the ground is trivial compared to maglev systems. While some maglev technologies must be built like a bit of a monorail, which must be built elevated everywhere. And if we step outside of high speed rail, and point to rail in general, the mere existence of level crossings and street running disproves the fact it can only be built grade-separate. Sure, level crossings for HSR are a reason for the planning engineer to get fired, but for rail in general, it can happen.
  this depends on what is already there. Most high speed trains use standard gauge, and those that don't, use broad gauge, and for that, only the Russian Sapsan comes to mind. If your country has standard gauge track, you can use the existing railway lines into town, disproving your point. And as for signalling, you can fit a train with multiple train protection systems, and many places are instead working towards using high speed signalling for general use, since the tech that makes high speed trains go BRR is the same tech that allows regular trains to run closer together. Finally, electrically, many countries use the same power on the wires on their high speed network as their general network.
  I've seen footage of a set of switch points with a diverging speed of 160 km/h, and it needs 9 switch motors to work. Proper high speed switches need even more, last time I checked the adopted standard was diverging speeds of 220 km/h. However, these motors all work in parallel, so the difference in switching time is negligible compared to a more basic type for general use. And these points work by bending one rail a little bit out of the way, bending another rail into place, and for high speed, pushing the frog (image for clarity) to the other side. This all unlike maglev, where you need to invasively rearrange the whole track, the replacement of which is probably several metres away.
  High speed rail has enough compatibilities with regular rail to make sense.

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.
- 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.
  
  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.
  
  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)
  
  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.
  
  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.

They're super expensive. Few people are willing to pay the massive amount extra for the slight dectease in travel time. Investors also know that.
- Look at HS2 in Britain and how people are against the cost for higher speed options, or California HSR. I'm all for it, it should absolutely be done, but getting taxpayers to see 10 years into the future is difficult.
  
  Brits are opposing HS2 simply because they are NIMBYies and oppose everything.
  
  That's because HS2 is a totally flawed, Ill thought out, over budget and badly managed boondoggle - just like everything in the UK rail system since the Beeching cuts in the 60's. If it was properly run, well thought out - and actually made a significant difference in time (not approximately 15 minutes from Piccadilly to Euston), we'd support it.

What is a Maglev train? (From WIki)
Maglev (derived from magnetic levitation) is a system of train transportation that uses two sets of electromagnets: one set to repel and push the train up off the track, and another set to move the elevated train ahead, taking advantage of the lack of friction. Such trains rise approximately 10 centimetres (4 in) off the track. There are both high-speed, intercity maglev systems (over 400 kilometres per hour or 250 miles per hour), and low-speed, urban maglev systems (80–200 kilometres per hour or 50–124 miles per hour) under development and being built.
Why so little?
Despite over a century of research and development, there are only six operational maglev trains today — three in China, two in South Korea, and one in Japan. Maglev can be hard to economically justify for certain locations, however it has notable benefits over conventional railway systems, which includes lower operating and maintenance costs (with zero rolling friction its parts do not wear out quickly and hence less need to replace parts often), significantly lower odds of derailment (due to its design), an extremely quiet and smooth ride for passengers, little to no air pollution, and the railcars can be built wider and make it more comfortable and spacious for passengers.
Cute link to the Wikipedia Page
I am a curious human, beep boop

Plane maglev tracks are way more expensive than wheeled train tracks. It's slower to get expensive when the terrain stops being plane, but it takes a lot of roughness for it to become cheaper. Most countries just do without trains crossing rough terrain.
And the largest cost of almost any train is the tracks.

Where existing transit infrastructure exists, cities prefer upgrading existing infrastructure, rather than installing new infrastructure in its place, and where transit does not exist cities prefer not to install anything at all and favor cars typically. Maglev trains are extremely expensive to install the infrastructure, so gathering the money out of local budgets to invest in the extremely expensive maglev infrastructure is typically very difficult.
In the US in particular, politicians, just don’t look at the picture in the long term, and only focus on short term investigator as it pertains to their election schedule, and that is sad and has long-term impact on the local population.
- Think about it this way, OP: You know when they're working on the train network, how much you loathe commuting while a single line is out? How much of a pain replacement bus transportation is?
  Now imagine having to do this for all train lines, everywhere, and you always have to switch trains (due to the difference in track) in between the blocks of replaced track. Plus you can't neatly fit maglev where conventional track fits and vice versa, plus you need the power infrastructure, plus you need to find a way to buy the rolling stock without already selling the old one.
- Also for the US the automotive and oil industries have powerful lobbies and an obvious interest in preventing the proliferation of electric-powered public transport. They’ve spent decades centering personal automobiles as the default method of travel and attack these projects with enthusiasm.

I read it's the zoning and maintenance of the tracks. Since they probably have to be very precisely laid in order to support such a fast train.
That said I do wish for maglev trains to be accessible to all. I'd love to go across the states in a few hours on a train.
- Plus, any maglev project has to be a new build and not outright replace existing lines. Replacing a line would require closing and removing the existing line, extensive reconstruction of the track bed, and probably delays or closure to tracks sharing the line. It's not an easy thing for the government to justify when it would be cheaper and easier to simply improve the existing rail infrastructure. Or..you know...ignore the problem which is what they seem to be doing anyways

You still need rubber wheels when it's stopped and at low speed. They retract when it's fast enough for the maglev to take over.
The electrical conductors are expensive as shit. The ones in the train need to be super cooled or something. The track ones need to be built along the entire length. On three sides, one vertically and two horizontally. Along with massive power lines along the whole length. They don't need to move to be expensive.
The right of way needs to be very straight. So compared to normal high speed, you have to spend much more on buying land, earth moving, tunneling, etc.
All this needs to be maintained to an extremely high degree because you can't accept a failure. The engine on a high speed rail fails and you just slow down, no biggie. HSR track is fairly robust and can easily be inspected visually. Since it has the same base as normal passenger and freight you have an entire industry knowledge and inspection machines. Any part of maglev fails and you have a catastrophic failure.
- The ones in the train need to be super cooled or something
  maglevs arent using fuckin superconducters to levitate, it's basic magnetic repulsion. Get whatever fictional version you've got in your head cleared up.
  
  They absolutely can, the one currently being built in Japan does: http://www.ejrcf.or.jp/jrtr/jrtr68/pdf/14-25.pdf page 19-20
  
  Here's the one I was thinking of, superconducting magnets for the japanese one SCMaglev https://youtu.be/XjwF-STGtfE?si=jrnttpIrmHBXMtUF
  
  Both of you guys are correct, because there are two types of maglev trains; the Japanese tech (Shinkansen) and the German design (trans rapid).
  
  Bit savage but your phrasing just cracked me properly up in public

One other thing I've not seen mentioned yet is capacity. Switching a maglev track is difficult and very slow, which reduces the number of trains you can get through a switch and therefore the number of people your system can carry.

I remembered seeing a video by Real Engineering that explained a lot on Maglev and it's pros and cons but one of the summaries that really hit it off for me and if I remember correctly is that it cost 11 times more to build per kilometre compared to conventional high speed rail, for about 70% more top speed while using 30% more energy.
https://www.youtube.com/watch?v=S4L_0CDsd1I
Personally I feel unless they come up with better superconductors, there's still a long way to go before it really takes off.
- Here is an alternative Piped link(s): https://piped.video/watch?v=S4L_0CDsd1I
  Piped is a privacy-respecting open-source alternative frontend to YouTube.
  I'm open-source, check me out at GitHub.

We don't have yet room temperature Supra conductors, it's also why there was so much buzz about LK 99 this summer
- Technically.... We actually do, but not simultaneously room temperature AND room pressure. There's one known material known to be superconducting at absolutely insane levels of pressure. That's not sustainable for any reasonable usecase of superconductors.
  https://www.sciencenews.org/article/superconductor-room-temperature-pressure-physics-electricity
- What happened with that by the way? I'm assuming since I haven't seen huge headlines since, it's not been replicated or it's been proven to be a hoax
  
  Not replicated, they found some anomalies in the samples skewing the results
  https://futurism.com/room-temp-superconductor-fails-work-replicated
  https://www.newscientist.com/article/2386866-lk-99-mounting-evidence-suggests-material-is-not-a-superconductor/
  
  It was basically proven not to be a super conductor

Here's an interesting write-up about an attempt to develop a large-scale urban maglev system in the 1970s: https://en.wikipedia.org/wiki/Krauss-Maffei_Transurban
tl;dr: there were so many technical issues that when the West German company developing the tech lost funding and the Ontario government took over the project, they immediately abandoned the maglev concept and replaced it with linear-induction propulsion with steel wheels on rails (the mag, without the lev).
Even this tech, which does have a few advantages over conventional rail and is still used today in cities like Vancouver, is falling out of favour due to general logistical issues with using bespoke technology over conventional rail -- fewer people know how to build and maintain it, you're relying on usually just one company to supply your trains and infrastructure until the end of time, you can't reuse any existing infrastructure, etc. I'd imagine these issues still get in the way of maglev development today -- even more so because you can't even reuse existing rails
- It's very sad tbh if it's the reason. It means the companies are unable to teach their knowledge, expand their market and attract investment by themselves despite clear advantages. I wouldn't be surprised, but it's still sad imo.
  
  The core technologies that UTDC (then Bombardier, now Alstom) took from this is still being used all over the world. The new Vancouver SkyTrain is still using Linear Induction Motors.

As others here have already mentioned the infrastructure costs alone are a huge problem, where I live we are currently just trying to electrify the corridor and it’s not even the entire system, once again the overall rail infrastructure is already there (it’s just electrification) yet this is still going to take a minimum of a decade and the minimum cost is going to be more than $11bn, technically this saves money as you don’t need to buy a new fleet of rolling stock just upgrade the old ones.
So ya for a maglev you would need a completely different infrastructure and the rolling stock

It makes more economic sense to improve the rails we already have, and build faster trains to run on the existing rails (like the TGV), than building completely new infrastructure.

They're very expensive to build. That's it, really.
- If it had a significant advantage the expense would be worth it, but steel wheels on steel rails already have a coefficient of friction 10x lower than rubber tires on asphalt, so it's not worth it.
  
  You do save money on them in the long-run. I just assume it takes decades to get all that return on investment back out, thus any entity interested mainly in quarterly profits has little incentive to make the investment, which would be disruptive to their finances in the near-term.
  
  If we somehow remove the friction of air on train body. Then maglev would be zero friction transport.
  Edit : Oh my. My little joke comment has ballooned into a full on debate. And I'm not even aware of any of these things they're all saying.
  I just made a comment guys, I'm not serious or not in any agenda.

They're quite expensive for a start and standard HSR does it's job just fine.
Japan is the only country that's building actual Maglev lines. It's feasible in Japan due to popularity of rail and distance between the endpoints makes it worth it.
China has Maglev tech and also some demo Maglev lines. But they are committed to standard rail because it's cheaper to build using a standardised process and works good enough on large distance travel required in China.
In the US, it's nearly impossible because Petroleum companies and such hate the idea of cheap and efficient transport and just bribe the politicians to be against it.
- I rode the maglev to the shanghai airport, it was awesome. The newer version in Beijing is significantly faster. But yeah super expensive to build.
  
  How was the ride? Smooth/bumpy/not feel much movement?
  My experience on a much slower HSR is being thrown around in the seat at certain times, wouldn't want to be carrying an open drink of any kind tbh lol

because cars cars cars
- More likely just the shear cost of building the tracks.
  
  oh yeah, definitely just prohibitive cost
- This argument may be true in regards to rail in general. This specific question is “why not maglev instead of rail”. That’s not car’s fault - it’s just extremely expensive to build maglev and that’s compared even to regular high speed trains.

I think they're just hard to find?

- Who are you talking to? OP didn't provide any links...
  
  Sorry, that was supposed to be in response to a reply to one of my comments - my bad!

What is a Maglev train? (From WIki)

Why so little?