Busy summer construction season ahead for SR 520 in Seattle

By Shoshana Wineburg

Big changes are on the horizon as we move closer to completing improvements along the State Route 520 corridor in Seattle. Both the Montlake Project and SR 520/I-5 Express Lanes Connection Project will reach major milestones this year.

What does this mean for you?

Residents in Seattle's Montlake and North Capitol Hill neighborhoods and travelers passing through the area will see a lot of construction activities – including extended closures – over the next few months.

Let's start with the work near Montlake.

Extended Montlake neighborhood street closures this spring and summer

Two major pieces of work for the Montlake Project involve realigning Montlake Boulevard and Lake Washington Boulevard into their final configurations. We rerouted those streets months ago to allow for extensions of the three-acre lid we're building over the highway. The upcoming realignment requires fully closing segments of these busy streets for extended periods. We're doing this work in two phases for each boulevard – for a total of four, around-the-clock closures.

First up is Lake Washington Boulevard. Starting Monday, May 1, we will close different sections of Lake Washington Boulevard around the clock for 19 days. This will be phase one; the second phase will start in July/August. For more information about the closure times and details check out our SR 520 Construction Corner.

The exact closure dates for the remaining three closures are not set, but we expect the work to happen between June and August. As always, construction schedules are subject to change. Information about local access, alternate routes and closure details will be posted on our SR 520 Construction Corner webpage as information becomes available. Be sure to sign up for our weekly email updates so you don't miss a beat.

In addition to realigning both boulevards, crews will replace underground utilities and drainage. For Montlake Boulevard, this means reducing the street to one lane in each direction
for one week after its first full closure.

Once complete, the newly reconfigured boulevards and lid will look like the picture below.

A rendering at what the new three-acre lid that will stretch across SR 520 will look like once the project is complete in 2024. It features 60 percent green space, realigned Lake Washington
and Montlake boulevards, transit stops and HOV direct-access ramps.

Opening new eastbound SR 520 lanes

In mid-summer, crews will close SR 520 for a weekend to begin shifting traffic onto a new eastbound bridge over Union Bay. This 1.2-mile-long bridge, built to current seismic standards, will carry three lanes of eastbound traffic from Montlake to the floating bridge.

Looking east, crews construct a new eastbound SR 520 bridge (at right), scheduled to open this summer. The parallel bridge at left, opened in 2017, carries two lanes of traffic in each direction. It will revert to a westbound-only span a few months after the new eastbound bridge opens.

What to expect for SR 520/I-5 Express Lanes Connection Project

You'll also see major elements of a new I-5 flyover ramp take shape this summer, marking the first major addition to I-5 in downtown Seattle in more than 50 years. When complete in 2024, this project will create a dedicated, reversible transit connection from SR 520 to the I-5 express lanes and Seattle's I-5/Mercer Street interchange. (Carpools will access this new connection once construction of the upcoming SR 520 Portage Bay project ends in 2030).

Constructing the new flyover ramp connecting SR 520 to the express lanes will require several road closures. Crews will first close parts of the I-5 mainline and express lanes during a late-May weekend to place the ramp's steel bridge girders. (Don't know what a girder is? Check out our last post). We'll share more details about exact closure dates, times and detour routes on our SR 520 Construction Corner as they become available.

Once that work is complete, crews will turn their attention to the westbound SR 520 off-ramp to Roanoke Street. We'll have multiple closures of that off-ramp over the summer so crews can finish building new retaining walls and shift the Roanoke off-ramp (and the westbound ramp to northbound I-5) into their final alignment.

A look at support columns built for a new, reversible transit/HOV ramp that's under construction
at the SR 520/I-5 interchange in Seattle.

More milestones to come!

As the year comes to a close, you can look forward to more completed improvements within the SR 520 corridor:

• The opening of a bike and pedestrian tunnel underneath Montlake Boulevard, connecting the cross-lake SR 520 Trail to the Bill Dawson Trail.
• The opening of a bike and pedestrian bridge over SR 520 – east of the Montlake lid – connecting Lake Washington Boulevard to East Montlake Park to the north.
• The opening of a regional transit hub on the new Montlake lid.
• And, last but not least, the opening of the three-acre Montlake lid itself! #LaunchTheLid!

How to stay updated about closure information

As you know, construction is dynamic and work schedules are ever-changing. Road closures and other construction activity can be disruptive for travelers, so we try to provide as much advance notice of our work as possible. We also try to avoid scheduling disruptive construction work during major public events. But given the level of work and limited timeframe, it's not possible to avoid every big summer event.

Here are the easiest ways to stay updated about closure information, as it becomes available:

• Check our online Construction Corner map
• Sign up for weekly email updates. Just enter your email address, and under "Construction, Planning & Projects," open "Projects," then "Rest of the West news."