Digging begins on Bellevue light rail tunnel

At the site of Bellevue’s new light rail tunnel, it’s striking what you don’t see.

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There’s no tunnel boring machine, like Bertha, which is digging a new Highway 99.

“We don’t have Bertha going through here so we dig it out by hand, more or less. That’s not really true but it’s a good story,” quipped Bellevue Mayor John Stokes.

This tunnel from South Main Street to near City Hall is being built with what’s called sequential excavation.

Crews use cutting equipment to remove small sections, then spray concrete on the walls and build structural supports.

Sound Transit uses tunnel machines on other projects.

So why not here?

“The depth of the tunnel — it’s a rather shallow tunnel,” answered Chad Frederick, of Sound Transit. “The bigger reason is that (sequential excavation) has less impact on the community.”

Construction managers say other tunneling techniques would require more road closures, and would be louder.

This site has a wall to muffle the noise.

A neighbor near the wall told KIRO 7 the project is already very loud.

A few blocks away, Cathy Sangster said the work hasn’t bothered her.

“At first we were afraid we would be hearing noise. But that hasn’t been the case. They have it all pretty much contained,” Sangster said.

Sound Transit and city officials say they are keeping neighbors notified about the progress of construction, which is expected to last two years.

Light rail service to Bellevue is scheduled to open in 2023.