11:28 AM: Even before the three-week closure of the West Seattle low bridge (formally, Spokane Street Swing Bridge) ended last Friday afternoon, the City Council’s Transportation and Public Utilities Committee had scheduled a briefing on the situation. That just happened during the committee’s meeting this morning.

SDOT‘s Meghan Shepard led the briefing, starting with a brief explanation of how the low bridge works, and a recap of what went wrong, resulting in its three-week closure to street/path traffic.

In addition to the leaking and electrical problems, SDOT found and fixed valve problems too:

(Here’s the full slide deck.) If they kept operating it with the leaky turn cylinder, they ran the risk of a “catastrophic failure” of other parts, Shepard said. It was reiterated that all four of the turn cylinders were scheduled for refurbishment this year anyway – this just moved up the schedule. They’ll all be removed and replaced sequentially. However, SDOT’s bridges/roadway structures leader Matt Donahue said – in response to a question from West Seattle City Councilmember Lisa Herbold – they’re not sure yet how long that’ll take, because they need “more time to determine everything that went wrong” with that cylinder, and to integrate technology upgrades. So with no timeline yet for all the cylinder repairs/overhauls, there’s no timeline for how long the bridge will be in the one-less-turning-cylinder, slower opening/closing mode. Herbold also asked how the resulting longer wait times are being communicated to bridge users; that too is a work in progress, Donahue said.

The briefing also included recaps of how SDOT quickly implemented a temporary protected bike lane – the 1st Avenue S. section has since been dismantled but the West Marginal Way one will stay indefinitely since a permanent PBL is already planned there; Shepard said the PBL was important because an average of 450 people bicycle across the low bridge daily. She also noted the week during which free bus/Water Taxi rides were made available, but said they don’t yet have metrics for how many people took advantage of the offer.

ADDED 12:45 PM: Here’s Seattle Channel video of this morning’s meeting – the low-bridge briefing starts 45 minutes in:

ADDED 8:41 PM: SDOT replied to our followup question seeking more information about the potential timeline. From spokesperson Ethan Bergerson:

We will overhaul four cylinders (two on each side of the bridge) before the bridge is once again opening and closing at the normal speed. At this point, we are considering replacing each cylinder one at a time in order to reduce the risks of more complications to bridge operations. This will be sequential as you described, but we haven’t determined the exact order.

We don’t have a time estimate yet, and it may take us several months to overhaul the entire set. We will continue to provide updates as the timeline becomes more clear. There are a few reasons for this uncertainty:

Our contractors and vendors are developing the scope and schedule for repairing the first cylinder. This will inform the overall schedule for all four cylinders, which will have to be aligned with the other improvements planned for the low bridge this year.

We won’t know the full extent of repairs needed for each of the other cylinders until after they have each been removed and dismantled so that we can see inside.

The time to obtain the necessary parts is still unknown. Many of these parts are unique and must be specially ordered or manufactured for this project, and potential supply chain issues are difficult to predict.

We will need to work with the US Coast Guard to schedule future cylinder removal and replacement activities in advance.