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Popular Science hypes Sound Transit I-90 bridge project

A graphic representation of what the East Link light rail line will look like across the floating I-90 Bridge over Lake Washington. Some Bellevue residents say they are not being properly compensated for the impact the project will have. (Sound Transit)

It’s not even finished, but Sound Transit’s East Link light rail over Lake Washington is already winning praise. Popular Science notes it as one of 2017’s most important innovations in engineering.

“From one-rail roller coasters to a fax machine for DNA, these are modern marvels of industry and design,” Popular Science writes in a recent article.

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The magazine notes a range of impressive scientific feats, such as a robot arm that can build copies of itself. Or a floating wind farm off of the coast of Scotland that produces enough power for 20,000 homes.

Right alongside these achievements is Sound Transit’s current East Link light rail project that will take passengers over the I-90 floating bridge. The extension is not reality yet, just a plan and a construction project at this point. The gumption to place light rail tracks on a moving, floating bridge was enough to impress technology editors at Popular Science.

Rails need to stay straight, but floating bridges bob and sway with the water beneath. Not a good match? Not a problem for Sound Transit’s new project. On this East Link Bridge—which will be completed in 2023—steel platforms and flexible bearings will let light-rail tracks stay in line. By 2030, 50,000 commuters a day will ride 148,000-pound trains at full speed across the water from Seattle to Mercer Island, Washington.

But advances in mass transit or even environmental progress pales in comparison to the engineering success that Popular Science awarded its grand prize to — a single-rail roller coaster. The new amusement park rides will take passengers on single-seat, open-air cars on a whipping ride that uses less steel and parts than previous roller coasters. Maybe it’s not too late to redesign the East Link bridge portion to incorporate this roller coaster tech and really impress the folks at Popular Science.

Check out the rest of the magazine’s notable advances in tech, from robot sea snakes to innovative sports stadium roofs.

East Link

Sound Transit promotes that a light rail line has never been extended across a floating bridge. To design the current project, engineers accounted for six different types of motion — up and down, back and forth, and side to side.

Part of the solution to a moving foundation is a “track bridge.” The track bridge includes bearings and plates that adjust according to the level of Lake Washington. Two bridge designs were tested in Colorado for the Sound Transit project. A range of data was collected, and one design won out — allowing a train to cross the lake at 55 miles per hour.

Multiple parts of the East Link line are under construction. It will connect Seattle with Bellevue and beyond. The bridge portion is expected to open in 2023.

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