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Name: Stephen
Status: Student
Grade: Other
Location: CA
Country: United States
Date: Summer 2009


Question:
What if the electricity on a maglev train goes out? Would that be catastrophic?



Replies:
Trains are designed to be safe and not catastrophically fail - be it due to a power failure or any other foreseeable problem. Designers try to think of all the possible failure mechanisms and design systems to "fail safely". There are lots of ways to make maglev trains "fail-safe" -- many companies tout new and less-expensive fail-safe methods. Some people consider today's maglev trains fail-safe, while others say they are not. It may be impossible to eliminate all accidents no matter how hard we try -- so by that standard nothing (cars, planes, trains, bicycles, etc.) is fail-safe. So it comes down to probabilities, and trying to reduce the likelihood of some catastrophic failure to as small as possible.

Hope this helps,
Burr Zimmerman


That would depend on how fast the train was going at the time. My guess is they have back up batteries that can provide enough power in the event of a power failure to bring it to a soft landing on their rails. That is just good system engineering, especially for a passenger carrying system.

Sincere regards,
Mike Stewart


Stephen -

I think that mag-lev trains generally have small wheels (or maybe skids) so they can coast short distances when not levitating, such as when the train intentionally rolls to a stop at a station. And if a train has wheels instead of skids, it must also have friction brakes, so it can stop within a known, reasonable and controlled distance. Emergency stops from unintentional power outages might cause more wear on the skids wheels'-brakes, because in normal operation at least the top half of the speed will be shed while still levitating, so during a normal stop the power dissipated in brakes or skids would be a factor of 4 or more less than the case of an emergency stop from full speed.

However any "good" (well-engineered) design should be able to absorb a stop from full speed without loosing braking control, and without loosing more than the normally-replaceable brake pads. One should presume that power _will_ be abruptly lost at least once in the train-system's life, so a responsible, safe design must be able to handle it without disaster.

To some extent it is up to informed citizens to make sure a good design is what's implemented. So keep asking such questions of any agency which proposes, builds, or operates an actual mag-lev project.

Jim Swenson


A maglev-type levitated train would settle down on skid pads and slide to a halt.

Some designs of levitating trains have them roll on auxiliary wheels at low speeds, and therefore a power loss would cause the train to settle down on the wheels.

Robert Erck



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