West Seattle Bridge notes tonight as the mayor’s repair-or-replace decision nears:
COUNCILMEMBER’S POLL: West Seattle/South Park City Councilmember Lisa Herbold sent email tonight launching a survey to ask you – repair or replace? You can answer here. Her email announcing the survey recaps what SDOT presented at last week’s Community Task Force meeting (WSB coverage here), from the forthcoming Cost-Benefit Analysis (CBA).
ABOUT THAT ANALYSIS: The day after the meeting, we asked SDOT if the full CBA document is available yet, or at least the missing cost-in-dollars projections. They replied today:
The final Cost-Benefit Analysis is not yet complete.
As you know, we are at zero percent design. We do not have exact cost estimates at this point and, from a Cost-Benefit Analysis perspective, it is more important to have apples to apples comparisons of the scale of various alternatives. The most critical aspect is understanding which options would likely cost more than the other to carry out (repair or replace) and which would be more costly over the long-run in terms of operations and maintenance. As we finalize the Cost-Benefit Analysis, we will be able to provide more detail on the conceptual cost estimates we have developed through the CBA process.
ABOUT THE CAUSE: Another followup question we asked was for elaboration on Technical Advisory Panel co-chair Barbara Moffat‘s mention during last week’s meeting that they now understand what went wrong with the bridge. Here’s the reply we got, also today: “While our confidence in our understanding of the physics affecting the bridge has grown with time as we’ve been able to test our advanced engineering modeling by watching the bridge behave as predicted in response to seasonal temperature changes and our initial stabilization efforts, it may never be possible to determine with 100% certainty a single underlying cause of the bridge cracking, or even if there was a single isolated cause.” We’ll keep following up.
STABILIZATION UPDATE: SDOT is posting stabilization updates every Monday; today’s edition is here. Key points include that the release of the stuck Pier 18 bearing might happen as soon as next week, as well as a note that those two work platforms under the bridge will likely be there until late November.