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

Updated: June 29, 2016  

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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

Construction activities

Beginning as soon as the week of June 13, crews will begin landscaping on Foster Island. Crews will transport habitat logs from the Old Canal Reserve area using the temporary work bridge and place the logs on Foster Island, near the Arboretum Waterfront Trail (see map below).

What you can expect:

  • Multiple truck deliveries during the day over the next few weeks.
  • Crews preparing soil for landscaping features on Foster Island.
  • Crews monitoring and controlling dust using water trucks near the Old Canal Reserve, as needed.

Click image for larger, printable version. (pdf 2 mb)

Arboretum Waterfront Trail Closure

The Arboretum Waterfront Trail is open at this time.

Expect an increase in construction activities from 5 a.m. to 11 p.m. throughout the summer

In addition to regular round-the-clock construction operations, crews plan to begin an additional summer shift next week. The work that has typically been taking place during the day, between 7 a.m. and 3:30 p.m., will now take place between 5 a.m. and 11 p.m. This extra shift will enable crews to continue to make progress on the West Approach Bridge North (WABN). As crews continue to make progress on the new WABN structure and move further west, you can expect that construction of the permanent structure will move closer to the MOHAI staging area.

During this new shift, neighbors can expect to see and/or hear:

  • An increase in truck traffic in the MOHAI staging area in the early morning and late evening hours.
  • Mobilization of equipment and preparation for construction activities.
  • Crews pouring concrete shafts, columns and deck for the permanent WABN structure.
  • Crews constructing falsework to support future girders for the new WABN structure.

This work will be in accordance with the temporary noise variance (TNV) granted to Flatiron by the city of Seattle. Use of noisy impact equipment, such as jackhammers, will occur before 5 p.m. as required by the current TNV.

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 WSDOT 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 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 10 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.