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

Updated: Sept. 12, 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:

Project milestones


Construction activities under a city of Seattle temporary noise variance

  • No activities currently under a city of Seattle noise variance

Construction activities

New SR 520 westbound lanes open to traffic

We opened new westbound SR 520 lanes to traffic early Monday morning, Aug. 28, as planned, between the floating bridge and Montlake. The milestone came 54 years to the day after the original SR 520 floating bridge opened. Working around the clock over the Aug. 25-28 weekend, crews paved the new roadway’s western segment, relocated the westbound SR 520 Montlake bus stop, striped new lanes, installed new signs, and completed the tie-in between the new lanes and the old westbound lanes to I-5. The pictures below show how the lanes changed from construction to finished product. For more photos of how it all came together, check our Flickr page.

Image shows the area previously under construction that is now the new westbound SR 520 lanes

SR 520 closures 

There are no SR 520 closures at this time.

Arboretum Waterfront Trail closures

The Arboretum Waterfront Trail is open.

Construction activities near the MOHAI and Old Canal Reserve staging areas

Activities in the next few weeks (September 2017)

Nighttime work

  • Flatiron night-shift crews will be working from 9 p.m. Wednesday, Sept. 13, to 6:00 a.m. Thursday, Sept. 14, to finish lane striping work on Lake Washington Boulevard and the new WABN westbound lanes.
  • Few trucks are expected to move through the MOHAI site during night shifts as the majority of trucks will access nighttime work via the eastbound SR 520 lanes.

Daytime work: Preparation for MOHAI restoration

  • Overview: As you are all well aware, the MOHAI area has been an active staging area, vital for preparing pieces of the bridge for installation and an essential access route to the work. Now, with the opening of the new westbound SR 520 lanes, crews are transitioning to restoring this area. The restoration work requires crews to perform intensive work right in the MOHAI area to transform this former museum and parking lot into a new grassy lawn. Below are more details of the work neighbors should expect during the coming weeks in the MOHAI area closest to your homes.

  • Covering materials over the weekend
    As needed, crews will cover the soil piles in the MOHAI area, closest to the neighborhood, to help control dust during times crews are not on site. Another best management practice that will be used on other stockpiles will be to shape and roll them, which will seal the surface to help control dust devils. They will not cover the larger materials (pavement debris, concrete pieces, etc.) that are stored on site because they are unlikely to be disturbed.

  • Reposition of fencing along East Park Drive East: ASAP
    WSDOT and Flatiron have placed fill at the edge of the old roadway, which has allowed for the repositioning of the temporary fencing at the corner of Hamlin Street and East Park Drive East. This will restore the roadway width and give vehicles more space while turning the corner.

  • Debris hauling: Sept. 9, Sept. 11 – Sept. 15
    Crews will continue the work they started this week of breaking up, loading, and hauling away debris from decommissioned parts of old and temporary SR 520 structures. This work will take place in the MOHAI area.
    Impact: Neighbors will hear this work taking place and may feel intermittent vibrations as trucks are loaded and hauled off site.
    Note: Crews will continue to work intensively, during daytime hours only, to reduce the number of days of impactful work. The noise and vibrations will be sporadic throughout the day. As crews pick material and load trucks, some loads may land louder than others and there may be large pieces that need to be broken apart with heavy equipment.

  • Grading and compacting: Sept. 11 - Sept. 22
    As the MOHAI site is cleared, nearby neighbors may hear equipment and feel vibrations as crews excavate and grade the MOHAI area. This work will create the final grade in preparation for grass seeding.

  • Landscaping in MOHAI: Sept. 20 – Sept. 29
    Where: Crews will be placing and spreading landscaping materials, including fertilizer and mulch, in preparation for grass seeding.
    Impact: Neighbors may smell the fertilizer and mulch.

  • Paving of new parking spaces on East Park Drive East: planned for Early October
    Crews will pave the final bay of parking spaces on East Park Drive East near East Montlake Park. This work is currently expected to take place early October.
    Impact: Nearby neighbors may hear mini excavators, a grader, and rollers as crews prepare the site. Crews will close part of East Park Drive East when the paving work occurs. We will provide an update once the paving schedule is confirmed.
    Note: This work will likely coincide with other paving efforts on the project to make efficient use of crews and equipment, while also minimizing the number of impactful days to nearby residents.

Daytime work: General

Landscaping and irrigation work on Foster Island: Sept. 11 - 12

  • Where: Crews will work on Foster Island below and around SR 520.
  • Impact: Crews will close the Foster Island Arboretum Trail from 7 a.m. Monday, Sept. 11, to 5 p.m. Tuesday, Sept. 12.

24th Avenue East Bridge roadway improvement: Sept. 18 – Sept. 22

  • Where: Crews will hydro-blast the east side of the 24th Avenue East Bridge deck where the sidewalk used to be. This area will then be resurfaced to provide a better driving surface.
  • Impact: Neighbors may hear the hydro-blaster as crews prepare the edge of the bridge deck for the resurfacing.

Landscaping in the Old Canal Reserve: TBD

  • Where: The work is on hold as the current configuration of the 24th Avenue East/Lake Washington Boulevard off-ramp has made access to the Old Canal Reserve area difficult. 


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

For boater information, please visit our SR 520 Boater webpage.


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.