Today’s WSDOT update on the Viaduct/Tunnel project, posted late today, is a new, long FAQ attempting to answer some of the questions that have come up since the December 5th disclosure of “settling.” Read it in its entirety here. Some of what caught our eye on first look include:
Our contract with STP allows up to two inches of viaduct settlement before mitigation is required. Should it be necessary, a number of techniques could be used to strengthen the viaduct and keep it open to traffic until the new SR 99 corridor is completed. These techniques could include strengthening columns or other areas of the structure to provide additional support. We could also reinforce the viaduct’s foundation as we did in 2008.
Regarding the plan to reach, lift, and repair the tunnel machine’s cutter head, WSDOT writes, “We’re disappointed with STP’s progress to date …” while noting the pit is now three-fourths of the way to the expected 120-foot depth, and expressing optimism that even if the current rescue plan has to be abandoned: “At its core, this is an engineering problem, one that can no doubt be solved.” The FAQ reiterates, “No significant settlement has been observed in the area since Dec. 5.” And as for the biggest concern of all:
Our bridge experts have confirmed that the viaduct remains safe for day-to-day use. If we had any reason to believe it wasn’t, we wouldn’t hesitate to close it. It’s important to remember, however, that the day-to-day safety of the structure does not change the fact that the viaduct remains vulnerable to earthquakes. That’s why it’s being replaced.
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