Magnetic trains

[kochman]

http://www.telegraph.co.uk/news/wor...310mph-floating-trains-unveiled-in-Japan.html

This is pretty fascinating.
Headline...

310mph 'floating' trains unveiled in Japan

Correct me if I'm wrong, but this should be much less of a polluter, no? I mean, there are no emissions from the train itself (ok, aside from electricity to keep the lights on, etc), and the manipulation of magnets would seemingly be the only real energy use.

 

[Phrossack]

Just wait until vactrains.

 

[hobbsyoyo]

Whether or not it pollutes depends on all what is used to generate all off the energy to levitate it and propel it through the air.

Plus, there is the issue of the incredibly dirty way that countries (and in particular, China, who has the market cornered) go about mining all of the rare earth minerals that go into building the trains and the rails.

 

[Cheezy the Wiz]

What I worry about with "frictionless" things like this is deceleration. Lots of room to go omgwtf horribly wrong.

 

[hobbsyoyo]

What I worry about with "frictionless" things like this is deceleration. Lots of room to go omgwtf horribly wrong.

You just apply force in the opposite direction of travel to slow down. They have safety wheels it can fall on if the system fails.

 

[Cheezy the Wiz]

What holds the train on the "tracks?"

 

[shadowplay]

Maglevs have been around for a while. Not sure what makes these new ones so much faster than the old ones.

 

[Synobun]

What holds the train on the "tracks?"

What keeps a plane in the air?

Like any form of rapid transportation, there is a delicate balance and system that makes it "work". Disrupting it can cause devastating issues but are inherently uncommon. I'd reckon that the chance of this train derailing is as unlikely or even less likely than a plane to crash.

 

[emzie]

I've always wanted to ride a maglev train.

 

[Gigaz]

What holds the train on the "tracks?"

I think it's the flux pinning of the Abrikosov vortices in a type II superconductor.

 

[tokala]

I've always wanted to ride a maglev train.

It's pretty much like the PR saying: "Flying at altitude zero", just without the engine noise.

 

[Glassfan]

What I worry about with "frictionless" things like this is deceleration. Lots of room to go omgwtf horribly wrong.

I've wondered myself what happens to a 400 kph train when say, a 7.5 Japanese earthquake unexpectedly hits? I looked-up " bullettrain earthquake" on youtube, but the one video was of a parked train during a minor shake. There's one story about a Chinese HS train collision resulting in 30-odd killed.

 

[Synobun]

I've wondered myself what happens to a 400 kph train when say, a 7.5 Japanese earthquake unexpectedly hits? I looked-up " bullettrain earthquake" on youtube, but the one video was of a parked train during a minor shake. There's one story about a Chinese HS train collision resulting in 30-odd killed.

Safety measures. They probably have computer link-up with disaster agencies. The moment an earthquake hits, the trains probably instantly lower their wheels and slow to a halt ASAP. Seems like the most reasonable thing to do.

Or maybe not. Maybe these trains have no safety measure at all and are just massive disasters waiting to happen once fully utilized.

But I'll consider the first option the reality, for now.

 

[Thedrin]

I think it's the flux pinning of the Abrikosov vortices in a type II superconductor.

Are these being constructed using super conductors? Are there high temperature super conductors now or is some of the energy cost going into cooling?

 

[kochman]

What holds the train on the "tracks?"

Magnetic repulsion/attraction.

You place magnets in key places, and it's fine... opposites attract and like repulse.

 

[hobbsyoyo]

Are these being constructed using super conductors? Are there high temperature super conductors now or is some of the energy cost going into cooling?

IIRC they do use super conductors and their are no high temp superconductors that do not require copious amounts of energy intensive refrigeration.

 

[Gigaz]

Are these being constructed using super conductors? Are there high temperature super conductors now or is some of the energy cost going into cooling?

IIRC they do use super conductors and their are no high temp superconductors that do not require copious amounts of energy intensive refrigeration.

There are superconductors which operate at temperatures above the nitrogen condensation temperature so they can be cooled with liquid nitrogen, which is not very expensive.

 

[hobbsyoyo]

There are superconductors which operate at temperatures above the nitrogen condensation temperature so they can be cooled with liquid nitrogen, which is not very expensive.

Factor in the cost of using N cooling along the whole track or at least along every train continuously, then tell me it's not expensive...

And are they even using those kinds of super conductors (which are expensive themselves as well)?

 

[dutchfire]

I rode the Shanghai Maglev once (430 kmh). It was nice, but it is a bit shaky. You certainly feel more vibrations than in a regular German ICE going at 200 kmh. It was hard to make a picture, since I couldn't keep the camera still because of the vibrations. Nice thing: They don't just have a high top speed, they also ac/decelerate like lightning.

Economically, they still seem to be gimmicks. There aren't that many routes short enough to make this competitive with air planes and important enough to warrant very regular trains (the Shanghai one goes every 6 minutes?), so that keeping the entire thing cooled down all the time is not a gigantic waste. Regular trains are also much more versatile and have all the existing infrastructure.

 

[Glassfan]

The Chinese bullet train collision killed 43 and injured over 200.

"The only derailment of a Shinkansen (Japanese) train in passenger service occurred during the Chūetsu Earthquake on 23 October 2004. Eight of ten cars of the Toki No. 325 train on the Jōetsu Shinkansen derailed near Nagaoka Station in Nagaoka, Niigata. There were no casualties among the 154 passengers.[16] In the event of an earthquake, an earthquake detection system can bring the train to a stop very quickly (how quickly?). A new anti-derailment device was installed after detailed analysis of the derailment." -wiki

Because of the risk of earthquakes, Urgent Earthquake Detection and Alarm System (UrEDAS) (earthquake warning system) was introduced in 1992. It enables automatic braking of bullet trains in the case of large earthquakes (how long?). -wiki

Spoiler :

31 December 1983: A bomb allegedly planted by the terrorist organisation of Carlos the Jackal exploded on board a TGV from Marseille to Paris; two people were killed.

But how fast can you stop a Bullet Train? How long does an emergency stop take? After all, it's a million tons of mass - it doesn't just stop on a dime. If it did, a lot of passengers would fly into forward bulkheads.

Spoiler :

"Something I think that is often neglected when talking about High speed trains is how long they take to get to their top speed and how long they take to go from top [operating] speed to full stop.

I have been looking for information on the actual... figures and it seems that the information is difficult to find." - NetComment

Spoiler :

"The service brake (not the "emergency" brake) is used during normal operation of the train and it achieves 0.6 m/s from max. speed down to 200 km/h and 0.8 m/s from 200 km/h down to 0 km/h as effective average deceleration. The service brake uses electro dynamic brake and mechanical brake." -wiki

So under normal braking, a train moving at 250 mph would take about 35 seconds to break? It would be stopped after the earthquake was over?

And how fast can a derailed bullet train stop? Off the track, it's normal breaking systems are disengaged and the train would slow to a stop based on friction with the earth.

My intuitive guess is that by time the train has slowed to a full stop, the worst of the earthquake will actually be over. Can anyone do better?

There doesn't seem to be a lot of Web-based information on this. Obviously not something manufacturers or operators want the public to worry about. But to be fair, high speed rail does seem to have a good safety record.