Now that stalled tunnel machine Bertha’s front end is disassembled, the damage looks worse than project experts thought. Contractors will miss their August goal to resume digging on Washington’s Highway 99 replacement project in Seattle.
Bertha, the world’s biggest tunnel-boring machine, overheated and quit digging on Dec. 6, 2013. The machine is stuck near Pioneer Square, some 1,083 feet into the 9,270-foot route from Sodo to South Lake Union.
The highway tunnel is two years behind schedule, and is now estimated to open in early 2017.
Contractors have blamed the stall on a leftover steel pipe that Bertha hit underground, but the extensive damage suggests the machine may have suffered from inherent weaknesses.
