Traffic Shift Coming to Allow for Montlake Boulevard’s Expansion to Nine Lanes

A rendering shows a complete aerial view of the Montlake Boulevard/SR-520 project. (Credit: WSDOT)

This coming weekend Montlake Boulevard over SR-520 will be completely closed between Roanoke and Hamlin Streets so that the entire roadway can be shifted east onto what will become the Montlake open space lid. The change will allow for crews to extend the lid structure to the west, making space for the newly rebuilt Montlake Boulevard.

With the Montlake drawbridge closed to vehicle traffic until the morning of Friday, September 3rd, this closure will not be as impactful as it otherwise would be, and people biking and rolling will still be able to access the entire Montlake Boulevard corridor as usual. However, the work accomplished this weekend marks a pivotal point in the overall 520 replacement project in Montlake and also provides a valuable chance to look back on how we arrived at this point.

By this fall, both Montlake Boulevard and the 520 overpass at 24th Ave E will be moved to the new Montlake lid so the lid can be expanded. (WSDOT)

By next year, a new Montlake Boulevard will fully take shape where the current one stands, but with nine motor vehicle lanes directly over 520 in comparison to the six that existed prior to the start of construction. Two lanes in each direction will be through lanes, while four of the additional lanes will all be turn lanes, including a southbound left and right turn lane and two northbound left turn lanes. The remaining northbound lane will be dedicated to transit and paired with a direct transit connection on the Montlake lid, although with no southbound transit lane counterpart. The northbound bus-only lane will continue a bit north of 520, according to project plans, stopping in advance of the Montlake drawbridge.

The new Montlake Boulevard will extend to nine lanes of traffic next to the Montlake open space lid.

To accommodate all of the turning movements directly over 520, the southbound bus stop along Montlake will end up down at Roanoke Street in contrast to the direct connection to 520 buses that will be available to northbound riders.

Location of the bus stops after the completion of the new Montlake Boulevard. (WSDOT)

How did we end up with a nine-lane Montlake Boulevard?

Like so many road expansion projects, the answer to why Montlake over 520 was expanded into nine lanes is partly attributable to bunk traffic volume forecasts.

The traffic analysis, conducted for the 520 replacement project’s Environmental Impact Statement (EIS) in 2011, used data showing a 15% increase in traffic by 2030 at the Montlake interchange during the morning peak period and a 21% increase during the afternoon peak period. According to that EIS, if no changes were made, the eastbound ramps at 520 and Montlake Boulevard would see so much traffic that they would end up 50% over their designed capacity, compared to only 15% over their designed capacity with the highway expansion. Whew, disaster averted.

The EIS cites a 2006 report from the Puget Sound Regional Council that “the region” would “need to accommodate close to 40 percent more traffic” by 2030, a fact that only seems relevant in retrospect for how wrong it now appears to be, at least in Seattle. Average daily traffic volumes in the city have been almost completely flat since that report was put out, even declining a bit when the biggest sources of traffic, the state-controlled bridges like SR-520, were not included in the yearly counts, as shown below.

Average daily traffic volumes in Seattle did not increase as they were forecast to in 2006, but the design of the new Montlake Boulevard assumes they will. (City of Seattle)

In an effort to advocate for more dedicated transit in the Montlake Boulevard corridor, the Seattle City Council went on record in 2010. “Dedicated HOV/transit lanes should be provided on Montlake Boulevard…WSDOT should also commit to working with SDOT to consider extending the dedicated HOV/transit lanes on Montlake Boulevard to the north, and on 23rd Avenue to the south. The southern corridor should be reviewed as far south as the intersection of Madison and 23rd Avenues,” noted a letter submitted as part of the EIS process and signed by all nine councilmembers at the time. But the Durkan administration missed a more recent opportunity to add bus-only lanes to the 23rd Avenue corridor as part of a recent rechannelization, or road diet, on that street, and the Route 48 “transit plus multi-modal corridor project” along that street has the smallest planned budget of any transit corridor improvements moving forward, only a little over $2 million. The 520 project was clearly a missed opportunity for improving transit access through the corridor.

Of course, the four-lane Montlake drawbridge will remain a pinch point for transit for the foreseeable future, with dedicated transit lanes on that bridge a nearly impossible lift. The 520 project actually plans a second bascule bridge over the Montlake Cut, something that the City of Seattle has never supported: not in 2010 when the city council commented on the EIS, and not in 2019 when interim Councilmember Abel Pacheco tried to introduce a resolution supporting a new bridge if the added capacity went to transit, bicycle, and pedestrian space. That resolution went nowhere, with then-transportation committee chair Mike O’Brien making clear he did not support adding any new roadways.

An aerial image shows a second bascule bridge next to the existing Montlake Bridge.
Councilmember Mike O’Brien helped beat beat WSDOT’s effort at road widening in Montlake–for now anyway. (WSDOT)

Recent comments by State Senator Jamie Pedersen, who represents the district where the new bridge would be built, suggest that the state may seek to reallocate funding for that second bascule bridge to other projects given the lack of political will to push that project forward without city support. The second bascule bridge may be dead, but the added road capacity over 520 will remain.

New pedestrian and bike connections will improve mobility in the corridor

Another part of the project happening right now is excavation work to create a tunnel under Montlake Boulevard just north of 520 that will enable the Bill Dawson Trail, which connects to Montlake and enables people walking and biking to avoid most of the 520 ramps, to eventually connect directly with the Montlake lid and the shared-use path across the lake.

Work is happening right now to tunnel under Montlake Boulevard, providing a bypass for the Bill Dawson Trail. (WSDOT)

The pathway will also connect directly with the planned “land bridge” (i.e., pedestrian and bike overpass) overlooking Union Bay on the east end of Montlake, taking the place of the temporary underpass on that end of the 520 project that is currently in place during construction.

Zoomed out view of the entire Montlake project including the new Montlake Boulevard (left) and “land bridge” (far right). (WSDOT)
Detail of the “land bridge” on the east side of the project. (WSDOT)

The bike and pedestrian overpass is a result of the Montlake lid being scaled back dramatically compared to the original concepts for the lid. A 1,400 foot lid was originally envisioned in Montlake, but after working with the Seattle Design Commission, an 800 foot lid moved forward that removed “areas of the lid that would have had poor public access and would not have met the project goals of providing safe public space,” according to WSDOT’s update to the EIS. The larger lid would have necessitated ventilation structures and an operations and maintenance facility, which would have themselves taken up space on the lid itself. The coming “land bridge” will be the best connection for people on bikes to connect from the Washington Arboretum up into Montlake. Unlike a normal overpass, it is being built with heavy landscaping and overlook features that will make it function a little more like a freeway lid.

The original design for the Montlake lid was much larger than the one being built now. The design went from a 1,400 foot lid to an 800 foot one. (WSDOT)
View from the planed bike and pedestrian overpass on the east end of Montlake. (WSDOT)

The entire Montlake project is expected to wrap up by 2023. The bike and pedestrian connections, many of which have not really existed before, are going to significantly improve mobility through the area. But rebuilding nine lanes of Montlake Boulevard over 520 really illustrates the degree to which this megaproject reflects an outdated mode of thinking in which Seattle needs to accommodate more and more vehicle traffic. It also reflects a missed opportunity to fully plan around transit, and not only accommodate it as a side project.

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Ryan Packer lives in the Summit Slope neighborhood of Capitol Hill and has been writing for the blog since 2015. They report on multimodal transportation issues, #VisionZero, preservation, and local politics. They believe in using Seattle's history to help attain the vibrant, diverse city that we all wish to inhabit. In December 2020, Ryan started a three-month stint as editor of Seattle Bike Blog.

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The design of this project shows that the City is still run for the benefit of cars over pedestrians and transit. The pedestrian experience around this lid, the lack of crosswalks and center islands, the 9-lane roadway, the horrible walking paths to transfer to/from the southbound route 48 bus – the entire project was designed for car throughput and pedestrians and transit efficiency were a complete afterthought and have to suffer many compromises.

There are no good transit pathways. Even the vaunted HOV lane coming off the bridge has a signal on top of the lid at the 24th Ave intersection. And there is no good transit priority crossing the Montlake bridge.

The existing 520 roadway had great transit stops which allowed for a lot of connections between buses on SR-520 and buses going north-south on 23rd Ave/Montlake Blvd. That allowed a lot of transit opportunities, whether it was express buses to Kingsgate and Woodinville, or all day and night service to Kirkland and Redmond. Often 90% of the passengers on such buses were headed to downtown Seattle but 10% might be accessing UW, the hospital, the stadium, the Montlake neighborhood. You can’t duplicate the service and removing this transit stop will eliminate a lot of options, whether it is unloading football patrons without forcing every bus across the Montlake bridge, or keeping direct downtown service that also provides some UW access. Sending every bus to UW will just subject every bus to Montlake Bridge congestion, openings, stadium events.

It was a bad decision to take a facility that worked well for sixty years and remove functions and dedicate so much space to cars – and do it in a way that transit becomes less convenient and less attractive. Congratulations, Montlake community, who did not stand up to WS-DOT and let WS-DOT do what they do best: build a more car-centric landscape. May you live in eternal congestion and pollution.


The one issue that concerns me is how buses will get from the UW to the East Side. Going the other way looks great. But a bus will cross over the Montlake Bridge, use that bus lane on the right, and then suddenly switch over to the bus lane on the far left, before turning left. That doesn’t sound easy, and will definitely complicate things.


Nine lanes is a lot, but look at how that compares to the situation before they started:

Two lanes each direction — Same.
Southbound right turn lane — Same.
Southbound left turn lane — Same.
Bus Lane — Same.
Two northbound left turn lanes — Right now there is one.

Things are getting shifted around a bit. The bus lane is extended south (which is a good thing). Northbound riders heading west will turn earlier, and not be asked to do a U-Turn. But fundamentally it is the same, other than having two northbound left turn lanes. This is overkill, but it isn’t the end of the world. This reduces the backup of cars trying to turn left. It also means that the light cycle can be shorter. Both of these benefit transit (the buses never make that turn).

If you look at pictures before the work (or just remember what it was like) you will note that it was always very wide at the south end of the overpass. There was a big triangle on the west side of the street. Cars heading eastbound on 520 would go on the inside, while buses would go on the outside. Pedestrians were forced onto the triangle, just to cross the street. This triangle is gone, while the sidewalk is widened. Overall, it doesn’t look much different than it did before.


… the Route 48 “transit plus multi-modal corridor project” along that street has the smallest planned budget of any transit corridor improvements moving forward, only a little over $2 million.

… the state may seek to reallocate funding for that second bascule bridge to other projects given the lack of political will to push that project forward without city support.

Couldn’t the money from the state go into adding bus lanes on 23rd? That seems like an appropriate and wise use of the money. Instead of wasting money on a second bridge, the city can use it speed up the buses, and still have money left over for additional projects.

Pat Crenshaw

The reduction in lid size mentioned in the article erroneously uses the unit of “square feet”. The E-W length of the lid was reduced from 1,400 feet long to 800 feet long.

Ron Swanson

Time for the city to come to its senses and seize the opportunity to get transit lanes and improved bicycle and pedestrian access across the cut with a second drawbridge.

Absolutely insane to refuse state $ to improve one of the city’s biggest bottlenecks.


The original plan for the second drawbridge didn’t do anything for transit and simply added more car lanes. It would have come at the cost of several homes and large trees, plus a ton of money. I say, it’s just as well that the second bridge is killed. As long as transit has priority in the bottleneck leading up to the bridge (which it does), it’s good enough.


Exactly. Buses will be able to get right to the bridge in their own lane. Then they will merge for a short section, and then get into their own lane again. This will happen both directions. General purpose traffic will build up before the bridge, but not over it. This is because the buses are skipping to the front. In this way, it is similar to the 520 lanes leading up to the 520 bridge. They caused general purpose traffic to crawl, but once everyone reached the bridge, all vehicles went fast.

In this case, it avoids the biggest backup, which is when the bridge goes up. Buses will be able to get to the front of the line, and go right when the bridge closes. In contrast, cars arriving late will be stuck in traffic, as they wait for all of the cars to move.

Nick vdH

Really disappointed with the location of that southbound bus stop. Can’t believe connections to the 520 buses are going to be worse than before with the unaccessible staircases.


It’s only really an issue for those heading to the Montlake neighborhood. The bulk of the 520 buses will be turning north to the U-district, so those headed to the U-district will simply stay on the bus.

Still, the lack of an at-grade crosswalk on the lid is inexcusable, and makes access to the southbound bus stop more cumbersome than it needs to be. There are plenty of signal phases where cars are already stopped and allowing people to cross would have negligible impact on traffic flow.


It seems like it would be pretty easy to add a crosswalk later. My guess is most of the people in the area (and even the city) are just waiting for the dust to settle, knowing they could add things like that later. It is stupid to add all of those lanes, but even that could change if they wanted to. It is easy to make things narrower (just expand the sidewalk) — much harder to make the bridge wider.


“It seems like it would be pretty easy to add a crosswalk later.”

From a technical standpoint, yes. But, in practice, the addition of transportation officials will be elsewhere. The biggest cost, of course, would be the traffic study to prove to WSDOT beyond a reasonable doubt that adding a crosswalk will not delay car traffic beyond the allowable 3.14159 seconds.


There are plenty of signal phases where cars are already stopped and allowing people to cross would have negligible impact on traffic flow.

No, I don’t think that is true? The E/W traffic is an exit ramp, so either N/S traffic is flowing or exit ramp traffic is turing left. I don’t think there will be a light cycle where there is neither northbound traffic coming from the south or turning from the west.

Also, the is a crosswalk on the south side of the interchange is a much shorter walk given several less lanes. A crosswalk in the middle of the lid would be inviting people to cross in front of traffic when the road is at its widest and therefore would delay N/S buses the most.


Looking at it some more, it is really only an issue for those headed south from the East Side (e. g. Kirkland to the Central Area). The other direction it will be great. For riders going from Kirkland to the Central Area, the best option is to just stay on the bus one more stop, and cross at Shelby. You encounter a tiny amount of overlap, but that is a straightforward (and short) crossing.I think it is fine as is.

Ott Toomet

Will there be any changes for cyclists who are crossing Montlake bridge southward to connect to the 520 trail (or the other trail)? Currently you have to use the eastern side of the bridge, and then either continue on the sidewalk till on the left side of the Mountlake Boulevard till East Hamlin street, or turn into East Shelby street in the wrong direction to avoid going on sidewalk.

I could imagine either making wider dedicated multi-use sidewalks there, or alternatively turning the Shelby-Hamlin street traffic direction around, so you could turn straight into Shelby and return on Hamlin. The dedicated sidwalk/trail sounds like a better option to me when thinking about connecting to the new underpass.

Nick vdH

The sidewalks there were redone within the last couple of years, and are wide enough to accommodate bikes comfortably in my experience (wider than the sidewalk on the bridge)