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Nov. 13, 2015 Bertha testing is underway as crews race to meet its most recent deadline for restarting: Dec. 23. Crews test various pumps inside the machine, as well as the screw conveyor system that carries excavated material from the cutterhead to the back of the machine and out of the tunnel.

May 2015 Crews discover damage to Bertha is more extensive than previously thought. The tunneling start-date gets pushed back.

The WSDOT also publishes reports on the fact that the viaduct is sinking.

Aug. 24, 2015 After reassembling Bertha and wrapping up repairs earlier in the month, crews lower Bertha's front end back into the pit. The rest of the machine's major components are safely lowered into the pit by Sept. 8. The ensuing weeks are focused on welding the pieces back together.

March 30, 2015 Bertha's 2,000-ton front end is lifted to the surface for repairs. The lift began around noon and the piece is visible at the surface a few hours later. The lift didn't finish until the following afternoon.

Feb. 18, 2015 After sitting idle for more than a year, Bertha breaks through a concrete wall into an access pit. The WSDOT announces the machine will continue moving forward in 6.5-foot increments, stopping to build rings on its way into the pit. Once the front end is fully exposed, crews will begin the disassembly process.

Feb. 7, 2014 The WSDOT says Bertha's seals and bearings are damaged. Tunnel workers performed 158 hours of hyperbaric inspections and found many of the cutterhead openings clogged with dirt and other material.

Crews hope to finish repairing the machine and resume drilling by Sept. 1, 2014.

Jan. 3, 2014 The WSDOT says the culprit for the work stoppage is a steel casing installed in 2002, following the 2001 Nisqually earthquake, that was used to help geologists better understand how groundwater moves in the area. Crews drilled 17 exploratory probes in front of the machine to look for objects that might be blocking the machine's path.

Jan. 28-29, 2014 STP restarts drilling and moves another 4 feet. Overheating forces it to stop again. The WSDOT stops making public statements.

Dec. 4, 2013 About 24 hours after recording its most productive day yet, and moving ahead of schedule, the machine hits an 8-inch steel well casing. Reports say the casing was absent from a geotechnical report, but available in secondary documents. It also reportedly hits a large boulder or chunk of concrete. The drilling continues.

Dec. 7, 2013 Bertha overheats. WSDOT says they've stopped tunneling after "unanticipated and increasing resistance was experienced, possibly due to an obstruction." Bertha has completed a little more than 1,000 feet of the 1.7 mile tunnel.

July 30, 2013

Bertha begins its 9,720-foot journey under Seattle at the waterfront.

The 5-story-tall cutterhead breaks through the north wall of the 80-foot-deep launch pit expecting to emerge about 14 months later near the intersection of Sixth Avenue North and Harrison Street.

The plan: Dig about 6 feet per day, and by the time the machine is beneath downtown, dig up to 35 feet per day.

Bertha and Seattle tunnel project 2015