Light rail over I-90 to start final phase of testing

You can expect to see light rail trains crossing Lake Washington sometime this month. Sound Transit is about to start the final phase of testing before opening for service.

Up to now, only a few train cars have gone across the lake, being pulled along the tracks during load testing. Now it’s time for them to make the trip under their own power.

“We’ve been doing system integration testing,” Sound Transit’s Rachelle Cunningham said. “That’s one of the phases that all of our extensions go through before opening. So that’s been going on for a month or two, and we’re about completed with that. That’s almost successfully completed.”

The trains should start rolling soon.

“Around mid-December, we should move into that phase, and that will mean that people will see trains running across the I-90 floating bridge throughout the day,” Cunningham said.

As we reported on Friday, the goal is to start service before the start of the World Cup next June.

“We don’t have an official opening date yet, but we can confidently say it will be before May 31,” Cunningham said.

Sound Transit is working really hard to get it done even sooner.

This project across the lake is running three years behind schedule. Revenue service was set to begin in 2023 before a series of issues put it behind.

Looking back at the I-90 light rail project

I remember walking along the tracks in July of 2019 with the Sound Transit engineer who pioneered the design to take rail across a floating bridge, something that has never been done in human history.

It was so amazing to see the concrete blocks or plinths being used to help the rail remain stable on a floating surface. Even engineer John Sleavin appeared impressed by his own work.

“We tested our trains from walking speed up to 55 miles an hour, which is our maximum running speed, to prove that it works,” Sleavin told me at the time. “A lot of time and effort went into making sure this unique design, that’s never been done anywhere in the world, could accommodate this.”

Just a few months after that site visit, it became clear that there was a problem with those plinths. They were bad. They had to be replaced. The track had to come up. It was a devastating blow. Then came the pandemic. There was a concrete driver’s strike. And here we are.

No matter when it happens next year, it will be a huge deal to get trains across the lake.

“Everyone is super excited about this,” Cunningham said. “We’re going to have so many more options for getting around the entire region once this opens. So everybody is very excited. These are some very cool technologies that we have on the I-90 floating bridge, and it’s going to be a world’s first.”

I have long said that the public won’t feel the complete impact of the light rail expansion until it gets across Lake Washington. Opening up the Eastside to mass transit like this will be a game-changer.

While it likely won’t take a huge percentage of cars off the lake bridges, the light rail will provide a much faster and more reliable trip for those who use transit currently.

Trains don’t get stuck in traffic. Buses do.

Chris Sullivan is a traffic reporter for KIRO Newsradio. Read more of his stories here. Follow KIRO Newsradio traffic on X.

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