March 24 - Seattle Tunnel Partners has successfully lifted the first three pieces of the tunnel boring machine (TBM) Bertha to the surface for repairs in Seattle, Washington.

HLPFI reported on January 23 that Mammoet USA had been contracted to recover Bertha - the largest TBM in the world - after it was stopped 304.8 m into its underground operation after damage was discovered to the seals, which are located at the front of the machine.

The first piece lifted weighed in at 270 tonnes, while the second and third units weighed around 90 tonnes. All three pieces make up part of the TBM's exterior shield.


The first piece being lifted from the ground.


Three of four units have now been raised from the ground.


With the shield now removed, Seattle Tunnel Partners is preparing for the final lift, which involves hoisting Bertha's huge cutterhead and main drive unit, weighing around 2,000 tonnes in total, from the ground.

A bespoke modular lift tower, designed by Mammoet, will be used to lift the machine.

The video below explains Seattle Tunnel Partners' repair plan in detail:



Watch a timelapse video of the first unit being lifted from the ground below:



You can also keep an eye on what's happening here, as well as by following @BerthaDigsSR99 on Twitter.

Bertha was built specifically for the Alaskan Way Viaduct Replacement Tunnel project, which comprises the construction of a road tunnel in the city of Seattle.