Bertha nearing maintenance stop after a week of ‘good tunneling progress’
Jun 21, 2016, 11:34 AM | Updated: 11:37 am
Crews build the foundations that will support the lower, northbound lanes of the future tunnel under Seattle. The tunneling machine Bertha is nearing its planned maintenance stop. (WSDOT)
(WSDOT)
Bertha is nearing another maintenance stop and the 3,000-foot milestone.
After a week of what the Washington State Department of Transportation calls “good tunneling progress,” the contractor for the Seattle tunnel project is preparing to let Bertha take a rest.
Seattle Tunnel Partners have now mined a total of 2,971 feet and installed 449 concrete tunnel rings. The top of the machine is about 120 feet below Post Avenue, between Madison and Spring streets, the state reports.
Crews have mined just under 1,500 feet since Bertha’s maintenance stop near Yesler Way.
Bertha could stop for several weeks, according to the state. The last stop lasted six weeks. The location of the next stop was selected because the soils in the area are dense and stable, “providing more suitable conditions for maintenance.”
During the maintenance, crews will inspect the machine and cutting tools. Once the work is finished, tunneling will resume toward First Avenue.
