SEATTLE — Mammoet’s heavy lifting engineers have lifted out the Cutter Drive Unit (CDU) from tunnel boring machine “Bertha.” The unit was lifted to the surface, rotated to lie face down and then skidded onto supports ready to be repaired.
Back in December 2013, Bertha stalled 120 feet underground while boring from South Main Street to the Alaskan Way Viaduct. Seattle Tunnel Partners, designer and builder of the tunnel, found it would need to repair the enormous machine, which was buried deep beneath the surface.
To reach the machine and make the repairs, it was necessary to create a deep, concrete-lined shaft down to the cutter. Mammoet then lifted the CDU out through the shaft from its underground location. Once raised to the surface, it was rotated and skidded onto a pre-constructed repair support system. The lifting of the heavy CDU was complex due to its difficult shape and asymmetrical weight distribution.
For more information, visit www.mammoet.com or call (281) 369-2200.
