Saturday/ Big Bertha’s troubles

Seattle’s State Route 99 boring machine* (Bertha) ran into trouble while boring through sloppy old tide flat dirt and fill material.   Some of the water and abrasive material made it past the seals designed to keep it out and into critical bearings for the cutters on the head of the boring machine, causing it to overheat.  So a big hole had to be dug to get to the cutter head, lift it out, and repair it.  (The stoppage occurred in December 2013, and the project is now some two years behind schedule).

At midday Thursday, the top portion of the SR 99 tunneling machine’s cutterhead broke through the southern wall of the access pit.  It will be several months before boring can continue, and there is still a long way to go.

*A tunnel boring machine with a cutting head that is 17.5 m (57 ft) in diameter.

2-22-2015 8-25-05 PM
Only about 1.000 ft of the State Route 99 Tunnel has been bored (at the tunnel’s south portal) .. there is still a mile and a half to go!
2-22-2015 8-22-29 PM
The pit to reach the boring machine’s cutter head is about 120 ft deep. Check out the inside of the wall on the left. The cutter head has bored through the hole’s concrete wall.
IMG_7164 sm
The local alternative newspapers are NOT happy with Bertha’s troubles. A terrain sinkage of about a quarter inch in the immediate ares is also blamed on Bertha’s digging.


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