Maglev and Electric Failure
Country: United States
Date: Summer 2009
What if the electricity on a maglev train goes out?
Would that be catastrophic?
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,
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.
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.
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.
Click here to return to the Engineering Archives
Update: June 2012