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Fri May 9, 2014
UW Labs May Move To Avoid Interference From Magnetic Light Rail Trains
For engineers that use sensitive equipment like electron microscopes, a train is a big, moving, magnetic nightmare.
That’s why Sound Transit and the University of Washington are hashing out a deal that would give the university $43 million to move some of its labs across campus, away from a new light rail line in the works set to run beneath them.
UW engineers are studying all sorts of new materials, like tiny medical devices and some that would allow windows to harvest energy. To do so, they rely on machines so delicate that they go a little haywire when big metal objects like elevators and trucks move nearby. The worst offenders are trains, even if they’re 80 or 140 feet underground, which is how deep Sound Transit plans on burying a new light rail tunnel.
"Things like an electric train can actually create what's called an electromagnetic interference disturbance," said Joel Kellogg, an electrical engineer who specializes in how vibrations and interference affect sensitive equipment. "It's kind of like a boat traveling through water — it kicks up a wake and creates some sort of a disturbance within the water that starts interfering with objects further out."
"So, in the case of an electron microscope, it does things like cause the electron beam to move, interfering with the images that are being taken," Kellogg said.
There are two solutions to reducing vibration and electrical disturbance: tinker with the train, or move the instruments. Vibrations can be reduced by plunking the train on very straight rails that sit on rubber rings.
But here’s the real problem: A train is a big chunk of metal, and when it moves, it messes with the Earth’s magnetic field. That confuses the sensitive equipment above and makes detailed images of things like humans cells or nanomaterials blurry.
"The bad actor is perturbation caused by a large metallic mass moving through the Earth's geomagnetic field," said Richard Chapman, associate vice president for Capital Projects at the University. "As far as we know, there is no known way to mitigate, cancel out, or shield at the source from this perturbation."
The university has been working on this problem for seven years. In the end, the only solution is to move the labs. That’s what the University of Minnesota decided to do when it ran into the same problem. And it’s what the University of Washington’s Board of Regents approved Thursday. Sound Transit has not yet approved the deal.