Let’s Build a New West Seattle Bridge That Carries Light Rail Too

West Seattle Bridge. (Credit: SDOT)

Yesterday, West Seattle got more bad news as the Seattle Department of Transportation (SDOT) announced the West Seattle Bridge would be closed for at least two years to allow for the extensive repair work it needs.

Even worse, SDOT Director Sam Zimbabwe cautioned it may not even be possible to salvage the bridge if the damage is too extensive. “It may not be possible to repair the bridge as it currently is,” Zimbabwe said, giving a nod to not just to the technical challenges but also the looming question of the “financial feasibility of repair.”

Further analysis will give us a fuller picture of the West Seattle Bridge’s salvageability. For now, we know that shoring up Pier 18, one of the primary supports of the bridge, is immediately needed, as Zimbabwe explained in a presentation.

Regardless of what the engineers find, the best path forward in the West Seattle Bridge’s deteriorating situation may well be starting from scratching with a brand new bridge designed to carry light rail as well. That would provide an elegant solution, helping to fund SDOT’s unexpectedly urgent megaproject while also possibly speeding up the West Seattle Link’s opening date.

In the meantime, emergency repairs may allow the bridge to reopen in a few years time while the new bridge is designed–again depending on what the engineers find. The bridge has already been closed for almost a month since Mayor Jenny Durkan and SDOT revealed the structural issue on March 23rd.

Going the route of repair may not buy the bridge much time. As Heidi Groover and Mike Lindblom reported in The Seattle Times, according to Zimbabwe the best-case scenario is to complete repairs that keep the bridge in service for another 10 years. Zimbabwe also cautioned that the crossing, which opened to traffic in 1984, will definitely not reach its full 75-year design life.

A bridge for everyone

The West Seattle Bridge’s shrinking lifespan is why the City of Seattle must embark on a comprehensive plan to serve West Seattle’s needs, as we’ve argued is necessary in Interbay, too. Transportation projects must serve our long-term goals and how we envision people getting around in “the city of the future” that Mayor Durkan often invokes. And where we’re heavily investing public resources, we must also plan for growth to further our goals around equity and housing for all.

West Seattle Link is tabbed to open in 2030 which means the West Seattle Bridge will need to be replaced on roughly the same timeline as Sound Transit aims to open light rail service to West Seattle. Why not construct a single bridge to serve both light rail and general traffic? And perhaps it could offer another all ages and abilities bike route into West Seattle and one that makes the climb to Alaska Junction more gradual than other options.

In normal times, the West Seattle bridge sees more than 100,000 vehicle trips per day, which is why funneling all that traffic to the narrower low bridge was deemed impossible. Gridlock would have resulted. (SDOT)
In normal times, the West Seattle bridge sees more than 100,000 vehicle trips per day, which is why funneling all that traffic to the narrower low bridge was deemed impossible. Gridlock would have resulted. (SDOT)

Granted Sound Transit 3 (ST3) timelines were set before passage of a $30 car tab initiative and the coronavirus pandemic caused slowdown to construction and the tax receipts that fund it cast considerable doubt on those schedules. Still combining SDOT and Sound Transit funds could be a way to make both projects more feasible.

For Sound Transit, piggybacking on a new West Seattle Bridge would solve one of the stickiest issues in planning ST3. The agency prefers a high bridge for West Seattle citing cost concerns, but several vocal West Seattle stakeholders fought to get a tunnel option included in the environmental study that will determine the project’s fate. Sound Transit estimates a tunnel would add at least $700 million to the project’s cost, require third party funding, and likely take longer.

West Seattle traffic flow during the high-bridge closure.  The low bridge is transit, freight, and emergency vehicles only. (SDOT)
West Seattle traffic flow during the high-bridge closure. (SDOT)

That said, Sound Transit’s preferred stand-alone fixed high bridge isn’t without its issues too, which include where to site it given close proximity to Port of Seattle operations on Harbor Island. The existing elevated option also is likely to require more property acquisitions. A combined light rail and automobile bridge would lessen the need for property acquisition and the conflict with Port operations.

Sound Transit’s alternatives all branch off south of the West Seattle Bridge after crossing the Duwamish to serve Delridge Way and Avalon. (Sound Transit)

A combined bridge could be an elegant solution and one within Sound Transit’s ST3 budget. Perhaps it could even speed up West Seattle Link’s opening so that we can reap the transit benefits sooner.

Crafting a transportation levy to fund it

The West Seattle Bridge cost $150 million when it was built in 1984. In today’s dollars that’s about $375 million, but construction cost inflation has likely been greater than monetary inflation alone. SDOT does not have the funding for the $23 million in needed emergency shoring work it has already identified, let alone the money for full repairs or a replacement bridge. However, a West Seattle Bridge is likely to become a top priority given how big of a part it has played in the city’s transportation network.

SDOT will likely need to advance another transportation levy to fund the West Seattle Bridge repairs and replacement. That newfound funding need will join a long wishlist that includes a Magnolia Bridge replacement, potentially a Ballard Bridge replacement, another batch of RapidRide upgrades for popular bus routes, and, one would hope, continued progress to our pedestrian and bicycle master plans.

Given the tumultuous rollout of Move Seattle Levy projects, SDOT didn’t do itself any favors in getting another vote of confidence in a levy likely to exceed a billion dollars. Still, a signature project like a West Seattle Bridge that accelerates light rail timelines could help propel the measure to passage–particularly if it goes to ballot once the economy is picking up steam again from this recession. The alternative of letting our bridges fall into the sea doesn’t seem too attractive either.

Why did the West Seattle Bridge fail so soon?

It’s been noted that the winning construction bid back in the 1980’s came in under budget, which has fed speculation that the contractor may have been desperate for work amid the recession and subsequently cut corners to make the skimpy budget work.

Another culprit that’s been kicked around is the 2001 Nisqually earthquake, which SDOT says lowered the bridge three inches at the time and may have ultimately sped the deterioration of its structural integrity. Shoehorning an extra lane of traffic on the bridge may have accelerated the aging of the bridge further–yet again showing the ‘add another lane to solve traffic’ mentality is self-defeating. (The new bridge shouldn’t go fall into this trap: two lanes in each direction will likely suffice.)

Whatever the reasons, the hoped for 75-year lifespan of the bridge has proven to be a pipe dream. Bridges that carry 100,000 cars per day take a beating. The comprehensive planning the City undertakes around the bridge’s replacement must involve prioritizing transit to increase ridership, lighten the load on the replacement bridge, and decrease carbon emissions so the City can meet its climate goals–our current trajectory isn’t promising.

Immediate fixes

For now SDOT has a complicated set of repairs to make just to ensure the West Seattle Bridge doesn’t fall apart–potentially collapsing into the Duwamish River. SDOT posted its repair plan on its blog; in short, it involves creating temporary supports to shore up the structure to allow the agency to tear out the old bridge bearings in Pier 18 and cement new ones into place.

Pier 18 repairs are considered the most urgent to preserve the West Seattle Bridge. (SDOT)
Pier 18 repairs are considered the most urgent to preserve the West Seattle Bridge. (SDOT)

This would be only the first step in saving the bridge, and the later steps aren’t even known yet. That’s why Seattle should begin making contingency plans in case the West Seattle Bridge can never reopen. Let’s get the next generation of bridges right so we’re not contemplating overhauls or managed decline while bridges are still in their 30’s. If done well, engaging in comprehensive planning that includes designing for light rail and other multimodal improvements on the new West Seattle Bridge would help ensure residents of West Seattle remain connected to the rest of the city long into the future.

The featured image of the West Seattle Bridge is courtesy of SDOT.

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Doug Trumm is The Urbanist's Executive Director. An Urbanist writer since 2015, he dreams of pedestrianizing streets, blanketing the city in bus lanes, and unleashing a mass timber building spree to end the affordable housing shortage and avert our coming climate catastrophe. He graduated from the Evans School of Public Policy and Governance at the University of Washington. He lives in East Fremont and loves to explore the city on his bike.

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[ad hom attack] And your logic is completely screwed up. You don’t know what the future plans for Transit are here in West Seattle. They’re going to tear down my building so that they could put the light rail here. And while on one level I would love to restrict access to West Seattle in order to get rid of all the Eckerson yuppies who have moved here and ruin the place for the last 4 years oh, they are not going anywhere. They got lots of cars and they got lots of money to put gas in those cars. And the distance The Detour requires is huge. I have a tiny carbon footprint now because I have been able to keep appointments on First Hill and elsewhere by using the West Seattle Bridge. I also ride the bus but I am not riding the bus until we know about this covid-19 because I have been assaulted twice on the bus and there have been at least two murders on the bus within a mile of me. Plus there was a guy who hijacked the bus and got caught at Westwood Village. Even with all that stuff I still would ride the bus if you could guarantee me I wasn’t going to die. But your logic is just infuriating. Better Minds than yours made the decision to put the bridge there in the first place. You insist on calling it The West Seattle freeway which is a pejorative term. [ad hom attack]

Capitalist Believer

The idea of not replacing the bridge is ludicrous. Seattle is already suffering from the resistance of progressives who have fought increasing road capacity for cars and buses for 40 years. Seattle now has some of the worst traffic in the country as a result. Population has exploded while road capacity has stayed the same. Light rail is 10x more expensive than cars and buses.

Drake ap

You obviously have a small family or no family.
You cannot transport kids to school, sports or even ts daily on a bus and get to work on time.


One has to wonder if you even bothered to read the article. How dare someone propose that people have many options (drive, walk, bike, and transit) to cross the peninsula! The horror of convenience for all!


So they promise us a bridge with light rail, and then we will get a bridge with no rail because of the cost. This is the same major that has been delaying for 3 years 1.4 miles of light rail.


So basically you would build a multi-billion dollar light rail line to West Seattle, with one, maybe two stops. You would still have to spend the money to build the line from downtown to past Spokane Street, where it would somehow merge with the bridge and then continue right up the Junction. You wouldn’t have a stop for Delridge riders, and the Avalon Stop would be moved from here https://goo.gl/maps/VnYREC35nJrwURZh8, to here: https://goo.gl/maps/eiDrp7LgM1ocoXfF6. The train would either run on the surface, which means it would be no faster than a bus, or you would run elevated, which means spending a bunch more money, and creating the same issues that folks complained about.

Sorry, this just won’t happen. They go to different places. The West Seattle light rail plan is stupid; there is no reason to make it worse. The bridge itself is a tiny part of the project. There are only three stations, saving a tiny amount of money while making them much worse (and probably eliminating one of them) just doesn’t make sense.

This is the problem with mass transit planning in this city. The more a transit line resembles a freeway, the worse it is. Notice that UW to downtown doesn’t come anywhere near the freeway? That is a good thing! That is why it is by far the most popular section in our system (and it would be even better if it included First Hill). Trying to shoe horn a light rail line into a freeway is a bad idea.

Derek C

The train wouldn’t get stuck in traffic…

Social Distance

Let’s not. Density is dangerous. Public transportation is suicide. Social-distanced single-family homes on large lots with safe distance between neighbors is the way of the future. Single-occupant vehicle travel is what we should be accommodating, not public transportation that I will never ride again.

Richard L Bullington

“public transportation that I will never ride again”

Glad to hear it. I wouldn’t want to get the cooties of your reactionary thought patterns.


Or you could just move out of the city, since you don’t walk anywhere or enjoy any of the venues it has to offer


Part of the benefit of ST3 was bringing a train to West Seattle on a path that gave us redundancy… so we never end up in this situation again! We need more ways off our peninsula to be safe! A one bridge solution saves money, but means we won’t have an effective means of egress for many years. And again, a single point of failure. Not ok by me.

We are the single biggest neighborhood in Seattle. This is an emergency. Seattle needs to fix or replace this bridge immediately. No excuses.

Bryan Jones

I was one of many workers who helped build bridge. It took months to sink the piers, months of pounding noise while we did site prep, survey control etc. It was thrilling to walk on the first horizontal slab. Most of the time my work was along the edge of the bridge deck, always wearing safety belts. I witnesses two falls where those belts saved lives. Later we would kid the guys who had fallen and ended up swinging under the bridge until rescue.


SDOT is talking of reusing the original set of 4 piers in the mid span high bridge and just replacing the 3 cantilever spans over the Duwamish.

That would be cheaper and faster than other options but likely preclude any light rail integration. And even at best, a combo light rail bridge would only be for 1/4 of a mile. The approaches (which are fine) aren’t getting replaced and likely aren’t build strong enough for light rail.

AJ McGauley

The timing of the bridge closure is strangely fortuitous. If it happens just a few years later, ST may be too far down the road of building their own bridge. Now, the cost savings of using the existing bridge’s footprint to serve cars & LRT should be very compelling for all key parties – SDOT, ST, and the Port – particularly by avoiding property acquisitions as you note.

Ironically, the silly WS Link stub in the ST3 plan actually provides some real flexibility. Opening WS Link later than promised so that it can share a structure with a new car bridge is a very easy story to sell to the voters, which can provide political cover for Dow and the Board to delay the opening of WS Link to be closer to the opening of the 2nd tunnel.

With the current bridge at 6 lanes, the new bridge likely will have 4 cars lane and 2 LRT lanes. Not sure if there is a need for bus lanes if only RR H will be crossing the bridge, if there are bus lanes before and after the bridge allowing the bus to bypass queuing traffic. A bike/ped path would be nice, particularly on the north side with views of the skyline. Could end up being a bit of a promenade with pop-outs to stop and sit, similar to the 520 bridge. But if only the bridge is replaced, and not the approach structures, that might be a hard sell.

Derek C

Can you demo the low bridge at the same time? Would it still be necessary in the new configuration?

Jesse Simpson

Why would you want to demo the low bridge too? It provides freight access to Harbor Island, bike and ped access from West Seattle to the rest of Seattle, and, for the next 2-10 years of the high bridge being closed, a critical transit and emergency route

Derek C

They’re already talking about shutting it down because the high bridge might collapse onto it…

Jacob Shafer

love the idea of building a new bridge with light rail in mind. lets also use 1% income tax to fund