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SR 520 - West Approach Bridge North Project: What's Happening Now?

Updated: March 23, 2017

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Project photos

See more photos of SR 520 construction
on our Flickr site .

Project overview

The West Approach Bridge North (WABN) project is underway in the Montlake area and on Lake Washington. Work hours may vary depending on the construction activity. Construction crews will continue to employ best management practices throughout construction to minimize impacts on the community and environment. Due to the dynamic nature of construction activities, construction plans are subject to change. WSDOT will provide the public with ample notice before construction activities or closures occur.

In the next few weeks, crews will begin the following activities within project boundaries:


Construction activities under a city of Seattle temporary noise variance

  • No activities currently under a city of Seattle TNV

Construction activities

SR 520 closures 

Full SR 520 Closure

Crews plan to close all lanes and ramps of SR 520 between 92nd Avenue Northeast and Montlake Boulevard from 11 p.m. Friday, March 31, through 5 a.m. Monday, April 3. The bicycle/pedestrian path on the new floating bridge also will be closed over that weekend.

Full closure map
Click image for larger, printable version. (pdf 491 kb)

During the closure, crews plan to:

  • Remove old, temporary tolling gantries on the Eastside.
  • Continue removing sections of the old westbound SR 520 off-ramp in Montlake and the never-completed R.H. Thomson "Ramps to Nowhere."

If weather is dry during the weekend closure, crews also plan to:

  • Repair sections of pavement on the existing SR 520, west of the west approach bridge.

Nearby neighbors may:

  • Hear crews removing the toll gantries (on the east side), daytime jackhammering, and nighttime concrete munching.
  • See nighttime lights illuminating the work site for crew safety.
  • Feel vibrations from ramp removal work.

I-90 and routes around Lake Washington will be open for drivers traveling between Seattle and the Eastside during the weekend closure.

Heads up Eastside transit commuters
Before, during and after the weekend closure, the Evergreen Point Road Park and Ride is scheduled to close. Crews plan to work around the clock to add parking spaces that will bring the lot to its full 50-stall capacity..

The lot is scheduled to close:

  • 11 p.m. Wednesday, March 29, to 5 a.m. Tuesday, April 4

This work is weather-dependent and may be rescheduled.

Stay up to date
Construction work is dynamic and weather-dependent, and crews and travelers often have to adjust to changes in the plan. Between email updates, follow us on Twitter and visit the SR 520 Orange Page for the most up-to-date closure information. On the SR 520 Orange Page you can also follow updates regarding the upcoming westbound SR 520 double-lane closures.

Eastbound SR 520 directional closures

Crews plan to close all lanes of eastbound SR 520 between Montlake Boulevard and the eastbound SR 520 on-ramp from Lake Washington Boulevard East to remove sections of an old SR 520 off-ramp and the R.H. Thomson “Ramps to Nowhere” closest to the highway.

Nighttime closures of eastbound SR 520 are scheduled:

  • 11 p.m. Thursday, March 23, to 5 a.m. Friday, March 24
  • 11:59 p.m. Saturday, March 25, to 6 a.m. Sunday, March 26
  • 11 p.m. to 5 a.m. nightly, Sunday, March 26, to Thursday, March 30

While the eastbound SR 520 on-ramp from Montlake Boulevard is closed during the times noted above, the following ramps will remain open (shown in the map below):

  • The eastbound SR 520 off-ramp to Montlake Boulevard.
  • The eastbound SR 520 on-ramp from Lake Washington Boulevard East.
  • Please note that I-90 will also be open during these closures for drivers looking for alternate routes.

EB directional closure
Click for larger image.

Nearby neighbors may hear the construction work, feel vibrations and see nighttime lights at the construction site as crews remove the old concrete ramps. For more details check out the WABN What’s Happening Now webpage.

Crews have a temporary noise variance in place to complete the ramp removal work during the eastbound closures.

Westbound SR 520 double-lane closure

With only a few sections of roadway deck left to place, crews plan to start pouring concrete for both the traffic and bicycle/pedestrian barriers along the new permanent WABN structure. To access these locations, two lanes of westbound SR 520 between the floating bridge and Foster Island are scheduled to close nightly from 9 p.m. to 6 a.m. the nights of:

  • Monday, March 20, through Thursday, March 23
  • Monday, April 3, through Thursday, April 6

The westbound HOV lane will be open for general use the nights of the double-lane closures. 

Arboretum Waterfron Trail closure

Crews plan to close a section of the Arboretum Waterfront Trail on Foster Island intermittently over the next couple of weeks to finish removing the temporary supports from the new WABN structure. If you are heading to the area, you’ll want to check out other trails during the following times:

  • 7 a.m. Monday, March 20, to 5 p.m. Saturday, March 25.
  • 5 p.m. Friday, March 31, to 5 a.m. Monday, April 3.
  • The trail will continue to close intermittently throughout the spring as WABN construction moves west. We will keep you up-to-date with future trail closures through these emails, the SR 520 Twitter feed and our SR 520 Orange Page.

    Arboretum trail closure map march 20 to april 3
    Click image for larger, printable version. (pdf 5 mb)


Construction activities near the MOHAI and Old Canal Reserve staging areas

Activities in the next few weeks

Roadway deck: Now that all 353 girders and 108 isolation bearings are installed, crews are moving right along with pouring concrete for the new roadway deck. Over the past few months, 37 of the 41 deck sections have been poured. Next week, crews plan to pour concrete the morning of:

  • Thursday, March 23
  • Saturday, April 1

In the weeks following, crews are scheduled to pour one section of deck per week, expecting to complete the base of the WABN roadway deck by mid-April. Neighbors who live near the WABN construction site should note that all concrete pours are scheduled to begin at 8 a.m. however, you may hear crews and trucks mobilizing as early as 6 a.m.

You may also feel vibrations during the day as crews:

  • Remove steel piles from the temporary work bridge: Crews will continue to use vibratory hammers to remove steel piles from the extension piers of the temporary work bridge. Crews have also started removing the steel piles from the main trunk of the temporary work bridge. They are starting near the new floating bridge and making their way west. As crews move further west towards the MOHAI staging area, you may feel vibrations. Crews plan to continue use of the vibratory hammer between the hours of 7 a.m. and 10 p.m. on weekdays, and 9 a.m. and 10 p.m. on weekends.  

Activities in the next month

  • Utility installation: Installation of drainage will continue in the Old Canal Reserve and MOHAI staging areas over the next few months as weather permits. This work may cause vibrations during the day due to the compaction of soil. 

Ongoing activities over the next few months

Ramp removal work near Lake Washington Boulevard

The only sections remaining of the old westbound SR 520 off-ramp to Lake Washington Boulevard and the R.H. Thomson “Ramps to Nowhere” are those that stand over water. In the next two weeks, crews will prepare the work site so that active removal work of the barrier can begin on Monday, March 13.

What to expect:

  • Hoe ram and muncherConstruction hours: Ramp-removal crews plan to work 10-hour days, seven days a week. All impact activity, such as jackhammering or hoe ramming, will be completed between 7 a.m. and 10 p.m. during the weekdays and 9 a.m. and 10 p.m. on the weekends. All nonimpact construction activities, such as processing ramp rubble, munching concrete or moving equipment around the site, may take place before 7 a.m. and after 10 p.m. Inspectors on site will ensure that nighttime crews stay under the decibel levels permitted by the city of Seattle noise ordinance.
  • Noise: As crews complete this removal activity, nearby neighbors may hear hoe rams or munchers (both pictured to the right).
  • Vibrations: Neighbors may feel vibrations from the ramp-removal work.
  • Lights: Neighbors may see lights used during nighttime work to keep the site illuminated and safe for crewmembers. Crews will make every effort to keep lights pointed away from homes, where feasible.

The removal work is expected to continue for the next three to four months. We will keep you updated through these emails as the work progresses. If you have any questions or concerns regarding the ramp-removal work, please feel free to call the SR 520 24-hour hotline at 206-708-4657 or email us at

Old ramps over water

Continued bicycle/pedestrian detour on Montlake Boulevard

Since the 24th Avenue overpass closed last fall, bicyclists and pedestrians have been detoured from 24th Avenue to the Montlake Boulevard sidewalk, via East North Street. For your safety, please continue to use the signed detour route along Montlake Boulevard, as shown in the map below. To avoid potential conflicts between bicyclists and pedestrians with construction vehicles and off-ramp drivers, the bicycle-pedestrian path across 24th Avenue East bridge will remain closed during this temporary configuration. For more information on this topic, check out our "Frequently Asked Questions" document.

Stay tuned for updates on bicycle-pedestrian access through this area as the WABN project is completed in 2017. WSDOT secured full funding in 2015 to build the remaining west side portions of SR 520 and is currently evaluating how to phase the remaining portions of the SR 520 Bridge Replacement and HOV Program. There may be additional changes as we identify how the next phase of construction interfaces with the WABN project.

Detour route

Click image for larger, printable version. (pdf 5 mb)

City of Seattle temporary noise variances

When needed, a temporary noise variance can be granted to Flatiron by the city of Seattle to allow the contractor to conduct noisier work outside the typical hours of construction.

  • The city's noise ordinance allows for variances for louder nighttime work between 10 p.m. and 7 a.m. on weekdays and 10 p.m. to 9 a.m. on weekends.
  • Use of noisy impact equipment, like jackhammers, will occur before 5 p.m. as required by the temporary noise variance.
  • WSDOT inspectors will monitor nighttime activities to be sure work complies with city of Seattle requirements.

Watercraft restrictions

Crews will continue on-lake construction activities near the Montlake shoreline and the Arboretum. Cranes and other waterborne construction equipment limit water access under SR 520 near the Arboretum. Canoers and kayakers should use caution when navigating near the construction zone and stay at least 150 feet away from all construction equipment.

During construction, many of the canoe/kayak landings in the area will remain open but we recommend using the launches in the Arboretum or the University of Washington's Waterfront Activities Center. If you are unsure which boat launch to use, take a look at the map below and/or contact our construction hotline at 206-708-4657

Click image for larger, printable version.
(pdf 262 kb)


Tree protection and removal

To make way for the temporary bridge and staging areas, crews removed trees as necessary on Foster Island and in the Montlake area. WSDOT worked with the city of Seattle to remove as few trees as possible, and will continue to mark trees for protection with orange fencing and will coordinate on replacement plantings.