While the West Seattle Bridge Community Task Force is holding its first meeting, SDOT has published an update on potential timelines/scenarios – if the bridge is not fixable and has to be replaced, for example, a replacement could be in place as soon as 2024. The full post is here; below, key excerpts:
…To ensure that the public has a similar baseline understanding of the bridge and related work as the TAP and Task Force, we want to share with you an update on current bridge work and what it means, in the broadest of terms, for when and how we might restore travel capacity across the Duwamish. The estimates shared below reflect best estimates at this time and are very much subject to change as we continue to gather additional information. They are helpful, however, for showing where we are right now and what pathways and corresponding crossroads sit before us.
The first step to determining the future of the bridge is to complete testing and analysis to understand the condition of the bridge and how it continues to change.
We learn more about the bridge’s condition every day. This past weekend, crews suspended by ropes and safety harnesses descended from the edge of the bridge to drill precision holes in the concrete and collect core samples. The concrete samples, extracted from several locations along the superstructure, will be tested to determine how resistant the concrete is to corrosion.
Soon, we will have enough information for an informed discussion about whether to repair or replace the West Seattle High-Rise Bridge.
We expect to complete our analysis on the structural stability of the West Seattle High-Rise Bridge in late June or early July. This information is critical to understanding whether repairs to the bridge are possible and provides important information needed to decide what is best going forward.
Our ultimate goal will be to restore the critical transportation connection of the West Seattle High-Rise Bridge as quickly as possible, in the safest, most effective way that puts the needs of the community and urgency of the situation front and center.
Critically, we will not be making this decision alone, and will work closely with elected leaders, partner agencies, our new Technical Advisory Panel of engineering experts, and the new Community Task Force representing affected communities in West Seattle and the surrounding areas.
While we do not have all of the information yet, we are beginning to better understand what tradeoffs and rough timelines could look like for repairing or replacing the bridge.
Just as we shared in April that we do not anticipate the bridge reopening in 2020 or 2021 if repair is possible, today we want to share what the corresponding timeline might be for replacement, should we collectively choose to move in that direction.
While we still do not know exactly how long it would take to repair or rebuild the bridge, and which path is best based on data and structural analysis, we do have a sense of the pros and cons of several options we want to share today, as we prepare to share a much more technical set of considerations in the coming weeks.
If repairs are feasible, they would take until 2022 at the earliest.
Repairs would potentially mean fewer lanes of traffic than the bridge carried before and would only extend the life of the bridge by approximately 10 years, when the bridge would still need to ultimately be replaced.
While these are some significant tradeoffs, this could also offer some big advantages. In addition to allowing vehicles back onto the bridge sooner, reopening the bridge for up to a decade could also give us more time to work with regional partners on the potential design, construction, and funding for a long-term solution to restore capacity across the Duwamish in a more deliberative fashion.
If repairs are deemed not feasible, constructing a new bridge could take, very roughly, four to six years (reopening approximately 2024 – 2026).
But then, the construction would be done, and the new bridge could last for 50-75 years, depending on what type of replacement option was selected.
There are many types of replacement bridges to consider, and the decision will likely depend on several factors including cost, timeline, and the health of the infrastructure around the current bridge. In addition to construction, the approximate four- to six-year timelines include public input, design, planning, and permitting.
Again, we will know more as to whether or not repairs are feasible later this summer, once we complete our analysis on the structural stability of the bridge. Any decisions before then would be imprudent, but has and will not preclude our efforts to prepare for all pivots that data might suggest.
In addition to completing testing and analysis, another immediate step for both repair and replace scenarios will be to stabilize the bridge.
We are continuing to gear up and prepare for the stabilization work that will be the essential next step for public safety, no matter what path is ultimately chosen. While we may be able to adapt and scale back some aspects our stabilization plans if we move towards replacement, we would still need to strengthen and support the bridge in order to safely demolish it prior to replacement work commencing.
This work will begin this summer and will likely consist of three phases …
Details on those phases, and what happens next, are in the full SDOT post. Meantime, we are covering the Community Task Force meeting, and will have that report later this afternoon.