Geotechnical drilling was set to begin yesterday on the 710 Tunnel Technical Study in the L.A. area. Currently the 710 freeway ends along the city of Los Angeles-Alhambra boundary but was intended to run north to a junction with the 210 and 134 in Pasadena. The tunnel technical study will assess the feasibility of building a tunnel to complete the segment. Caltrans and CH2M HILL will be performing the borings which will go up to 250-ft deep. Seismic lines will be performed as a part of the study as well. Source: LA Times.
WSDOT released an update on February 7 with some conclusions regarding the blockage that has stopped the Alaska Way Viaduct Tunnel Boring Machine, Bertha’s progress since December 6. Now they don’t think it was necessarily the well casing after all.
They cite two factors that contributed to the blockage. First, the cutterhead was clogged with material. You can see an cool short video of a worker unclogging the cutterhead. Not terribly dramatic, but still cool. The second factor was increased temperatures inside the equipment. STP discovered damage to a seal that protects the machine’s main bearing. They are still determining how the repairs will be done.
If you want to follow the chronology of this issue, read below for summaries and links to previous updates from WSDOT. And Check out the videos too! [Source: WSDOT]