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Bertha, world's largest boring machine, arrives in Seattle

Bertha, the world's largest tunnel boring machine, has finally arrived in Seattle's Elliott Bay.

The 7,000-ton machine arrived in 41 pieces. Crews will start assembling the boring machine in the coming days, in the pit near Pioneer Square where she’ll begin tunneling for the State Route 99 tunnel project this summer.

Just how big is it?

"It's roughly the same size as one of Washington state’s largest Jumbo Mark-II ferry boats," says Matt Preedy, the DOT's deputy manager for the tunnel project. 

With a diameter of 57.5 feet, it could swallow the current biggest boring machine, which is at work in Florence, Italy.

The state Department of Transportation has created a map highlighting the best spots to catch a glimpse of Bertha in the next few days, while she's still on the ship. 

Can’t make it to the waterfront? No problem. The WSDOT will have a live stream of Terminal 46 once the Bertha-carrying ship has berthed, probably on Thursday or Friday. You can also follow Bertha on Twitter, at @BerthaDigsSR99.

For more information on how this behemoth of a machine works, check out the animation below. You can also visit Milepost 31 in Pioneer Square to see a motorized, 10-foot-long model of Bertha.

Keith Seinfeld is a former KNKX/KPLU reporter who covered health, science and the environment over his 17 years with the station. He also served as assistant news director. Prior to KLPU, he was a staff reporter at The Seattle Times and The News Tribune in Tacoma and a freelance writer-producer. His work has been honored by the American Association for the Advancement of Science (AAAS) and the Knight Science Journalism Fellowships at Massachusetts Institute of Technology.