Magnetic trains

[Cheezy the Wiz]

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

But can you push it to Warp 9, Mr. Laforge?

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.

The shinkansen trains automatically stop when the earthquake early warning system registers movement above a certain threshold. It's really a fantastic system.

Magnetic repulsion/attraction.

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

What I meant was, what keeps it from flying off the side of the track. I envisioned something like a chute that would "hold" the train above the track, I didn't understand the under-grab design like this, that this was actually a monorail we're talking about:

 

[Glassfan]

The shinkansen trains automatically stop when the earthquake early warning system registers movement above a certain threshold. It's really a fantastic system.

I've read a lot about it now and I understand "automatic stop" (UrEDAS). But automatic stop is not instantaneous. It takes time to slow down all that mass x inertia without forming the passengers into pancakes.

An earthquake starts. Then UrEDAS senses the earthquake. Then the train starts slowing down - while the earthquake is quaking - disturbing the perfect alignment of track - imposing vector forces on the speeding train - knocking debris onto the track, etc.

And of course, if derailment takes place, there's no braking system at all - just blunt force trauma.

So how long does it take to automatically stop a train going at 250mph?

I've calculated above, based on sketchy information, that it takes about 35 seconds to (normally) brake a train going at 250mph (obviously longer for faster). 35 seconds is forever during an earthquake. How much faster is automatic stop?

 

[hobbsyoyo]

Glassfan, did you figure in airbrakes or physical brakes that engage the track to slow it in your calculation?

 

[Glassfan]

The service brakes was the only vague reference I could find. Presumably automatic stop as employed by UrEDAS, or emergency stop on other technologies (MagLev) probably employ some hybrid techniques. Presumably it would be faster, but how fast can you stop a million tons without hurting the passengers?

 

[Mr. Dictator]

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

What is this, 1989?

They've been using anti-plasmoid hypercoils in even moderately funded projects since 2000. Yes, occasionally, you'll see some AV-II's pop up, but generally only in quick fixes where one can't at least find a dirty Russian vari-fold push rig laying around from the mid 90's.

 

[hobbsyoyo]

An airline needs less than what, 20 seconds to stop from over 150mph? 2-3g's of decel (only achieved in a real emergency) will slow you down in a hurry - even faster than an airline.

 

[Cheezy the Wiz]

I've read a lot about it now and I understand "automatic stop" (UrEDAS). But automatic stop is not instantaneous. It takes time to slow down all that mass x inertia without forming the passengers into pancakes.

An earthquake starts. Then UrEDAS senses the earthquake. Then the train starts slowing down - while the earthquake is quaking - disturbing the perfect alignment of track - imposing vector forces on the speeding train - knocking debris onto the track, etc.

And of course, if derailment takes place, there's no braking system at all - just blunt force trauma.

So how long does it take to automatically stop a train going at 250mph?

I've calculated above, based on sketchy information, that it takes about 35 seconds to (normally) brake a train going at 250mph (obviously longer for faster). 35 seconds is forever during an earthquake. How much faster is automatic stop?

Earthquakes travel through the ground considerably slower than radio waves. The early warning system triggers automatic brakes above a certain magnitude, and unless the train is very close to the epicenter, it's quite likely that the train will be stopped or significantly slowed by the time any shaking in the area occurs.

 

[Glassfan]

Earthquakes travel through the ground considerably slower than radio waves. The early warning system triggers automatic brakes above a certain magnitude, and unless the train is very close to the epicenter, it's quite likely that the train will be stopped or significantly slowed by the time any shaking in the area occurs.

That's what I was looking for, thanks.

 

[Michkov]

An airline needs less than what, 20 seconds to stop from over 150mph? 2-3g's of decel (only achieved in a real emergency) will slow you down in a hurry - even faster than an airline.

Airline passengers usually wear seatbelts in those situations. I've never seen seatbelts in a train, not that I ever was on a bullet train.

 

[Cutlass]

I've read a lot about it now and I understand "automatic stop" (UrEDAS). But automatic stop is not instantaneous. It takes time to slow down all that mass x inertia without forming the passengers into pancakes.

An earthquake starts. Then UrEDAS senses the earthquake. Then the train starts slowing down - while the earthquake is quaking - disturbing the perfect alignment of track - imposing vector forces on the speeding train - knocking debris onto the track, etc.

And of course, if derailment takes place, there's no braking system at all - just blunt force trauma.

So how long does it take to automatically stop a train going at 250mph?

I've calculated above, based on sketchy information, that it takes about 35 seconds to (normally) brake a train going at 250mph (obviously longer for faster). 35 seconds is forever during an earthquake. How much faster is automatic stop?

35 seconds? Man, trains do not stop on a dime. I cannot imagine a train stopping that fast. What are you basing that on?

I read an article recently, which I don't recall all the details of, but it suggested that trains accel/decel/turn, at about 0.1G of force. I don't know where that article is not to confirm, and the Chinese may well build more aggressively than Americans.

 

[kochman]

Earthquakes travel through the ground considerably slower than radio waves. The early warning system triggers automatic brakes above a certain magnitude, and unless the train is very close to the epicenter, it's quite likely that the train will be stopped or significantly slowed by the time any shaking in the area occurs.

Having been in an earthquake, the '89 World Series EQ, I was outside... and I can verify through 1st person account... they move SLOWLY. You can watch as the ground ripples somewhere around the same speed as ripples in the water when you throw a rock in a lake (incidentally, fish HATE that).

 

[hobbsyoyo]

Airline passengers usually wear seatbelts in those situations. I've never seen seatbelts in a train, not that I ever was on a bullet train.

You don't wear seatbelts in a bus, which frequently do make quick stops.

What's your point? In an emergency, you stop the thing and worry about the passengers immediately after that. And are you sure they don't have seatbelts? I have never been on a high speed train.

 

[schlaufuchs]

Having been in an earthquake, the '89 World Series EQ, I was outside... and I can verify through 1st person account... they move SLOWLY. You can watch as the ground ripples somewhere around the same speed as ripples in the water when you throw a rock in a lake (incidentally, fish HATE that).

Yeah, my mom described the same experience for the '89 Loma Prieta. She said you could literally see the ground rippling towards you.

I've never been in a big one though. I hope I never do.

 

[emzie]

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.

Do you fly? Do you drive?

 

[Deaths Advocate]

Lets hope he hasn't taken the stabilizers off yet.

 

[Shaihulud]

A Maglev train should be able to come to a stop anytime. The only consideration give to the deceleration is the safety of the passenger, which im sure the relevant authorities have taken care of.

 

[El_Machinae]

Since we're talking about Maglev, it's time to re-introduce Quantum Levitation. If you've not seen this video, it will blow your mind (I hope).


Link to video.

 

[Borachio]

So... a skate board made of that?

 

[Winner]

Since we're talking about Maglev, it's time to re-introduce Quantum Levitation. If you've not seen this video, it will blow your mind (I hope).

Ok, I am now more willing to accept the possibility of Avatar's flying mountains...

 

[El_Machinae]

Everyone I've shown that to, in person, has 'whooped' in exclamation at some specific timepoint. It's different for each person, but eventually it shatters their view of reality.