5 ms·

What's interesting, the speed record for conventional bullet trains is 574.8 km/h, about 30km/h less! This was a TGV train, largely unmodified (although they di

by ant6n 12y ago

What's interesting, the speed record for conventional bullet trains is 574.8 km/h, about 30km/h less! This was a TGV train, largely unmodified (although they did increase the tension in the caternary). The wiki article about the speed record is interesting: http://en.wikipedia.org/wiki/TGV_world_speed_record http://en.wikipedia.org/wiki/TGV_world_speed_record Makes you wonder whether the overhead of maglev is really worth it.

m_mueller 12y ago
I'd imagine that the wear on rolling stock and tracks as well as the power lost to friction makes Maglev worth it if you actually want to operate close to such speeds.
- ant6n 12y ago
  I'm not convinced. Some conventional rail operates at close to 400km/h today. This will operate at 500km/h - in 15 years. But it's completely incompatible with existing infrastructure, and thus doesn't allow incremental updates of either the infrastructure or the trains (i.e. no service in the mean time, and no ability to reuse existing tracks and stations in cities). Then consider the amount of research that's been put into this, and the complex problems that needed to be solved -- it would probably cheaper to invest research into track that allows higher speeds with less maintenance (again incremental improvements possible). Then consider that most of the speed from this maglev comes from the geometry of the track. It's all tunnels and bridges. That's a giant investment needed to get to those speeds; and conventional rail with that track geometry could be similarly fast.
  - vilhelm_s 12y ago
    I guess the usual counterpoint is: they have to build a new track anyway (the existing one is getting saturated). Building a rail track or a maglev track costs about the same (almost all the cost is making the tunnels), and the maglev track is better, so why not go with the maglev. It was discussed a little bit for the new high speed train line in Britain, but rejected for the reasons you state in your first paragraph. But Japan seems much less worried about reusing trains (different lines are usually operated by different companies with different rolling stock). And somehow they were able to get this project funded even though it will be many years until first service---maybe they just are more competent than the west when it comes long-term investments? :) So maybe the trade-off came out differently there...
    - ant6n 12y ago
      Maybe it's a tech-fetish. The Germans tried the same thing with Transrapid for many years (between Hamburg and Berlin), but just ended up upgrading conventional rail.
vilhelm_s 12y ago
I think I've read somewhere that it's possible to run trains of steel rails really fast, but doing so creates lots of wear, so it would not be economical to do it routinely. That the big advantage of the maglev technology is not the absolute top speed, but the fact that the maintenance is cheap even at high speeds.
- ant6n 12y ago
  But it has to be economical: if the cost of wear over the life time of the system is less than the initial cost of building maglev, then you're still ahead.
cstross 12y ago
Actually, the TGV record was set by a specially-rebuilt train set that was heavily customized -- and the test crew reportedly couldn't stand/walk around the instrument car at speeds over 500km/h due to vibration. (The track they ran the test on was newly-laid and not yet open to regular traffic: they had to replace most of the overhead cables from the stretch where the train hit maximum speed due to arcing and shock waves.) The big difference is that the TGV record set pretty much an upper limit on steel-wheel speed -- horrible vibration, and the wheel rims were close to supersonic, which would have led to more shock waves if they'd pushed it faster. Similarly, Formula One cars go a lot faster than regular road vehicles, but you wouldn't want to commute to the office in one! Whereas this maglev test demonstrated a technology that would be comfortably usable at this speed.
- kuschku 12y ago
  Interestingly, the TGV record was broken by an unmodified Velaro-D train recently. Standard rolling stock, used the week before for normal transport, used a week after for normal transport.
  - cbr 12y ago
    Are you sure? I'm not finding anything about this. The TGV record is about half the speed of sound, which means the wheel rims are bordering on supersonic, so it's not a simple thing to talk about exceeding it.
    - littlejohnk 12y ago
      Why would the wheel rims rotate at twice the speed of the train? If the train advanced along the track 1m, surely the part of the wheel in contact with the track must also have moved 1m?
      - Retric 12y ago
        The bottom of a wheel is stationary relative to the ground. (X - X) The middle a the wheel moves at the same speed as the vehicle relative to the ground. (X + 0) The top of the wheel moves at twice the speed of the vechile relative to the ground. (X + X) Put another way, the top of the wheel must go faster than the vehicle or it does not rotate.
drzaiusapelord 12y ago
Maglev is patent encumbered and really only implemented by a solitary Japanese company with close ties to the Japanese government. The government wants to give you a loan if you buy the product, etc. It a dying concept, much like the concorde was for air. The limits, cost, complexity, etc aren't worth it and the market has been choosing against it for decades.
nightcracker 12y ago
That makes a lot of sense, since almost all of the resistance the train faces is air resistance.

by ant6n 12y ago

m_mueller 12y ago

I'd imagine that the wear on rolling stock and tracks as well as the power lost to friction makes Maglev worth it if you actually want to operate close to such speeds.

ant6n 12y ago
I'm not convinced. Some conventional rail operates at close to 400km/h today. This will operate at 500km/h - in 15 years. But it's completely incompatible with existing infrastructure, and thus doesn't allow incremental updates of either the infrastructure or the trains (i.e. no service in the mean time, and no ability to reuse existing tracks and stations in cities). Then consider the amount of research that's been put into this, and the complex problems that needed to be solved -- it would probably cheaper to invest research into track that allows higher speeds with less maintenance (again incremental improvements possible). Then consider that most of the speed from this maglev comes from the geometry of the track. It's all tunnels and bridges. That's a giant investment needed to get to those speeds; and conventional rail with that track geometry could be similarly fast.
- vilhelm_s 12y ago
  I guess the usual counterpoint is: they have to build a new track anyway (the existing one is getting saturated). Building a rail track or a maglev track costs about the same (almost all the cost is making the tunnels), and the maglev track is better, so why not go with the maglev. It was discussed a little bit for the new high speed train line in Britain, but rejected for the reasons you state in your first paragraph. But Japan seems much less worried about reusing trains (different lines are usually operated by different companies with different rolling stock). And somehow they were able to get this project funded even though it will be many years until first service---maybe they just are more competent than the west when it comes long-term investments? :) So maybe the trade-off came out differently there...
  - ant6n 12y ago
    Maybe it's a tech-fetish. The Germans tried the same thing with Transrapid for many years (between Hamburg and Berlin), but just ended up upgrading conventional rail.

vilhelm_s 12y ago

I think I've read somewhere that it's possible to run trains of steel rails really fast, but doing so creates lots of wear, so it would not be economical to do it routinely. That the big advantage of the maglev technology is not the absolute top speed, but the fact that the maintenance is cheap even at high speeds.

ant6n 12y ago
But it has to be economical: if the cost of wear over the life time of the system is less than the initial cost of building maglev, then you're still ahead.

cstross 12y ago

Actually, the TGV record was set by a specially-rebuilt train set that was heavily customized -- and the test crew reportedly couldn't stand/walk around the instrument car at speeds over 500km/h due to vibration. (The track they ran the test on was newly-laid and not yet open to regular traffic: they had to replace most of the overhead cables from the stretch where the train hit maximum speed due to arcing and shock waves.) The big difference is that the TGV record set pretty much an upper limit on steel-wheel speed -- horrible vibration, and the wheel rims were close to supersonic, which would have led to more shock waves if they'd pushed it faster. Similarly, Formula One cars go a lot faster than regular road vehicles, but you wouldn't want to commute to the office in one! Whereas this maglev test demonstrated a technology that would be comfortably usable at this speed.

kuschku 12y ago
Interestingly, the TGV record was broken by an unmodified Velaro-D train recently. Standard rolling stock, used the week before for normal transport, used a week after for normal transport.
- cbr 12y ago
  Are you sure? I'm not finding anything about this. The TGV record is about half the speed of sound, which means the wheel rims are bordering on supersonic, so it's not a simple thing to talk about exceeding it.
  - littlejohnk 12y ago
    Why would the wheel rims rotate at twice the speed of the train? If the train advanced along the track 1m, surely the part of the wheel in contact with the track must also have moved 1m?
    - Retric 12y ago
      The bottom of a wheel is stationary relative to the ground. (X - X) The middle a the wheel moves at the same speed as the vehicle relative to the ground. (X + 0) The top of the wheel moves at twice the speed of the vechile relative to the ground. (X + X) Put another way, the top of the wheel must go faster than the vehicle or it does not rotate.

drzaiusapelord 12y ago

Maglev is patent encumbered and really only implemented by a solitary Japanese company with close ties to the Japanese government. The government wants to give you a loan if you buy the product, etc. It a dying concept, much like the concorde was for air. The limits, cost, complexity, etc aren't worth it and the market has been choosing against it for decades.

nightcracker 12y ago

That makes a lot of sense, since almost all of the resistance the train faces is air resistance.