Transportation chief has concern about Seattle tunnel

SEATTLE — The head of Washington state’s Transportation Department told state lawmakers Wednesday she’s had concerns about a highway tunneling project under downtown Seattle since the digging began last July — and has asked the operators for information, including a plan to regain lost time.

In her note to legislators, Lynn Peterson said she has concerns about operations and critical systems with the tunneling machine named Bertha, The Seattle Times reported. The Transportation Department has discussed the concerns frequently with contracting team Seattle Tunnel Partners and this week sent a formal letter, she said.

The new Highway 99 tunnel is part of the project to replace the aging Alaskan Way Viaduct on the Seattle waterfront. Drilling has been delayed by extra machine testing last winter in Japan, by a labor dispute in August and, since Dec. 6, by a blockage. The $80 million drill was made by Hitachi.

Seattle Tunnel Partners plans to send a crew to the machine’s cutting face to look for obstructions and damage. The work will be done in compressed but breathable air. The machine is stuck 60 feet deep.

Four vertical shafts drilled last week failed to show exactly why Bertha stalled. Officials say the machine hit a steel pipe but that’s believed to be only part of the problem.

Chris Dixon, STP project director, told The Times earlier Wednesday that he didn’t suspect that the current stoppage was caused by mechanical flaws or internal damage, but by objects or problems in the ground.

Peterson said she plans to gather tunneling experts to make suggestions but she also noted that her department can’t “direct how STP does their work” or the state could bear increased risks and responsibility.