Bertha progressing well during viaduct closure

SEATTLE — The head of Seattle Tunnel Partners gave a positive report Tuesday about drilling beneath the Alaskan Way Viaduct, a process that has brought a two-week closure of the roadway.




"The tunneling's going very well," Chris Dixon of STP said on a conference call.

Dixon said there has been virtually no ground movement detected since Bertha left a maintenance stop Friday.

The machine has traveled 117 of the 385 feet it needs to go before the viaduct reopens to traffic.

Dixon said contractors are averaging about four concrete rings per day.

As Bertha advances, it places the 6 1/2-foot rings, which form the side of the tunnel.

"I'd say it's right where we anticipated it would be," Dixon said.

Dixon said that progress would vary from day to day, which is typical in tunneling.

"There are going to be days we'll only do two rings a day. Some days we'll do four. Some days we'll get up to six or seven so what we're really shooting for is an overall average of four rings per day," Dixon said.

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