Quote:
Originally Posted by aberdeen5698
This is far from my area of expertise, but I don't think that's necessarily the case. Dynamic braking doesn't require external power, so Skytrain can use the LIM to brake even during power outages. And since there are always at least four LIMs per trainset a LIM failure is not necessarily a make-or-break [brake?  ] issue either. It's really just a question of whether or not this is seen as being as reliable as the disc brakes.
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Since the LIM requires electricity to generate the magnetic fields to move the train, when there is no LIM power there would therefore be no magnetism in the LIM for propulsion, nor for LIM braking.
Every train still has conventional brakes so a train in a station won't move while the passengers are entering /exiting the train. You may notice or feel a slight movement just after the doors close, but before the LIM starts accelerating the train. I've noticed some station's tracks aren't perfectly level so the train may creep backwards or forwards slightly in the sub-second time it takes between when the brakes are released and the LIM starts moving the train forward.
Loss of power should cause the train to go into Emergency Braking (using the conventional brakes on the train) and make the train stop dead in its tracks. This Emergency Braking will also happen to every train in the area where power is out, so it is unlikely a still-powered train will run into a non-powered train.
Trains in an area that still has power shouldn't be able to enter a non-powered track area, since the still-powered train wouldn't be receiving a 'positive control' indication that the track block ahead is clear. No power = no way to signal to the rest of the network 'this track block is clear of a train'.
When power is restored, a train operator can enter the lead car, open the access panel for the train controls and (coordinating with the Train Control Centre) manually take the train to the next station so passengers can dis-embark.