SR 520 Construction Corner

The go-to source for information on SR 520 construction

During SR 520 construction, work will occur at several locations in Seattle, including the Montlake, Madison Park and Roanoke areas and along the I-5 express lanes. Currently there are two active construction projects, the Montlake Project and the SR 520/I-5 Express Lanes Connection Project. Check our Construction Map for information about what's happening now or in the coming weeks.

Click on any topic below to learn more about potential effects. For each topic, learn:

  • What to expect during construction. What might you see, where, and when?
  • Construction commitments. What have we agreed to do to manage these effects?
  • Construction practices to minimize the effects. What will we do to reduce effects?
  • More information. We offer some sources to learn more.

You can also view current Montlake Project work activity via our construction cameras.

Our community construction management plans, linked at the bottom of this webpage, detail the actions our contractor crews follow to limit the effects of construction on nearby neighborhoods and travelers within the highway corridor.


Heavy construction equipment

What to expect during construction

During SR 520 construction, our contractors perform a variety of construction activities. Each activity uses different types of equipment and creates different levels and kinds of noise. Each week, we publish a report featuring nighttime noise data and complaints.


  • Crews may work 24 hours a day, seven days a week throughout construction.
  • Typical work hours for the loudest (impact) work:
    • 7 a.m. to 10 p.m. weekdays
    • 9 a.m. to 10 p.m. weekends and holidays
    • Please note: On the SR 520/I-5 Connection project, heavy daytime traffic on I-5 and SR 520 requires some impact work to occur at night. Nearby residences will be notified in advance.

Working at night and on weekends eases weekday traffic congestion on SR 520, I-5, Montlake Boulevard and local streets, particularly when lane closures or detours are required. We are always looking for opportunities to reduce nighttime effects on the neighborhood, and we will schedule noisy activities during the day whenever possible.

Construction commitments:

  • WSDOT and the contractor will meet all WSDOT, federal, state and local regulatory requirements, and any contract and permit requirements.
  • WSDOT prepared a Construction Noise and Vibration Mitigation and Monitoring Plan that identifies:
    • Expected noise levels at many locations.
    • The risk of exceeding allowable noise levels.
    • Measures for the contractor to implement if noise levels are higher than allowable levels.

Construction practices to minimize noise:

  • The contractor will follow best management practices, WSDOT standard specifications, and local ordinances to minimize noise.
  • Examples of best practices include:
    • Noise monitoring of all nighttime work.
    • Using sand-, rubber- or plastic-lined truck beds for all haul trucks.
    • Using lower-noise compressors at night.
    • Using less intrusive back-up warning devices or using back-up observers for some vehicles.

More information







A pile driver in Lake Washington

What to expect during construction

WSDOT is committed to minimizing activities that would result in noticeable vibrations, but some activities necessary for construction are likely to cause vibrations. Construction activities that may cause noticeable vibrations include pile driving, constructing drilled shaft foundations and demolishing existing structures.

Construction commitments:

Construction practices to minimize vibration:

  • WSDOT will monitor vibration levels near SR 520 construction sites before beginning construction and will conduct preconstruction inspections as appropriate to set a baseline during the construction period.
  • During construction, vibration monitors will be used to ensure that the contractor stays within the limits outlined in the project contracts.
  • Read the Montlake Project Vibration Monitoring Plan (PDF 6MB) to learn how the contractor will track the level of ground vibration from SR 520 pile driving and other work in Montlake and Madison Park.

Air quality and dust

Worker spraying a building with water as it is demolished.

What to expect during construction

Certain construction activities may affect air quality in the vicinity of the construction site. Some of these activities include truck traffic, asphalt paving, earthmoving, and demolition.

Construction commitments:

  • WSDOT and the contractor will meet all WSDOT, federal, local and statewide regulatory requirements, and any contract and permit requirements.
  • The Montlake Project contractor, Graham, developed a Fugitive Dust Prevention and Control Plan that provides additional details on activities to mitigate air-quality impacts during construction. The SR 520/I-5 Connection project contractor will prepare a similar plan.
  • Graham also developed a Concrete Containment and Disposal Plan that identifies methods for controlling concrete dust, including dust from saw-cutting. The SR 520/I-5 Connection project contractor will prepare a Fugitive Dust Control Plan.

Construction practices to minimize air-quality effects and dust:

  • Applying water to active dust-generating construction areas, as needed, and if applicable, to other areas of the work site to keep the soil damp and minimize fugitive dust without creating unnecessary muddy areas.
  • During the demolition of concrete structures as well as loading of construction trucks with demolition debris, using a water spray to minimize fugitive dust.
  • When appropriate, installing tarps on trucks to cover their loads prior to leaving the site to control loss of material while the trucks are in transit.

Views, glare, and lighting

Road construction under bright lights.

What to expect during construction

SR 520 construction will cause temporary, and in some instances, permanent changes to views and the visual context of the SR 520 roadway within the existing landscape. Montlake Project construction activities will affect views of and the visual context of the Montlake area and Lake Washington. Construction on the SR 520/I-5 Connection project will affect views along I-5 between the SR 520 and Mercer Street interchanges. Some construction work will occur during the night and will require lighting to work safely. During the winter months (November through March), there may be increased work-zone lighting at the beginning and end of the workday due to decreased daylight hours.

Construction commitments

  • WSDOT and the contractor will adhere to all WSDOT, federal, local and statewide regulatory requirements and/or as required by the contract documents. This includes WSDOT standard specifications.
  • Per the Section 106 Programmatic Agreement, the contractor is required to limit the use of construction lighting as much as possible and keep necessary lighting shielded, directed downward, and pointed away from residences and other sensitive areas to the maximum extent practicable.

Construction practices to minimize visual quality effects

  • Use directional lights instead of floodlights; direct light to the work zones and away from residents to minimize light pollution beyond the construction zone.

Traffic and transportation

A road closed off with sign saying 'ramp closed'

What to expect during construction

SR 520 construction activities will cause traffic and transportation disruptions due to adjustments in existing roadways, temporary closures, detours, and changes to pedestrian and bicycle access through the area. Additionally, construction equipment and activities may occupy part of the roadway and construction truck traffic will be present on the highways and local roads.

Conditions on the SR 520 mainline will remain similar to previous conditions, with two general-purpose lanes in each direction between Montlake and the floating bridge. These projects will require some short-term closures of SR 520 and I-5, as well as nearby on- and off-ramps. Construction activities on major city arterials like Montlake Boulevard and Lake Washington Boulevard will require lane shifts on those streets.

Construction commitments

  • WSDOT will require the contractor to adhere to all WSDOT, federal, local and statewide regulatory requirements and/or other regulations as required by the contract. This includes WSDOT standard specifications and coordination with the city of Seattle.

Construction practices to minimize traffic and transportation effects

  • Major roadways such as I-5, SR 520 and I-90 in Seattle will be used for major material haul routes. Other major city arterials designated as truck routes will also be used to access these major roadways and construction staging areas.
  • The contractor will minimize short-term closures and limit necessary closures to non-peak traffic periods.

More information

  • The SR 520 Montlake Project Neighborhood Traffic Management Plan (NTMP) (PDF 4MB) includes more information about traffic-related concerns, traffic management during the construction period, and traffic-calming measures planned by WSDOT and the city of Seattle to minimize traffic impacts during SR 520 construction. Because the SR 520/I-5 Connection project is expected to have very limited impacts to local streets, WSDOT and SDOT agreed that an NTMP is not necessary for the SR 520/I-5 Connection project.
  • Much of the work on the SR 520/I-5 Connection project will be completed from the I-5 Express Lanes while they are closed overnight, reducing conflicts with motorists.

Utilities and services

A worker passes another worker some equipment.

What to expect during construction

SR 520 construction will require the relocation of some sewer lines and other utility lines along the SR 520 and I-5 corridor, including in the Montlake area. WSDOT and the contractor will notify potentially affected residents of work that may result in service interruptions or closures. One notable project is the replacement of a 54-inch-diameter city water line that runs under SR 520 just east of Montlake Boulevard.

Construction commitments

  • WSDOT and the contractor will adhere to all WSDOT, federal, local and statewide regulatory requirements and/or as required by the contract documents.
  • WSDOT and the contractor will coordinate with the city of Seattle prior to any service interruption.

Construction practices to minimize effects on utilities and services

  • Advance notification will be provided to potentially affected residents and other stakeholders before conducting work that may affect utilities or services. Notifications will include contact information for comments or questions.

Vegetation management and erosion control

A tree with a sign attached entitled 'Public Notice Protect Tree'.

What to expect during construction

Some trees and vegetation will be removed from the project areas near SR 520 due to a number of activities, including building permanent project features and preparing staging areas for construction activities. WSDOT has developed both a Montlake Project Tree and Vegetation Management and Protection Plan (PDF 4.8MB) and an SR 520/I-5 Connection project Tree and Vegetation Management and Protection Plan (PDF 3.7MB). The plans identify specifics areas where trees may be removed or disturbed. WSDOT will also prepare a Temporary Erosion and Sediment Control Plan for both projects to reduce water quality effects from construction

Construction commitments

  • WSDOT and the contractor will adhere to all WSDOT, federal, local and statewide regulatory requirements and/or as required by the contract.

Construction practices to minimize vegetation effects and control erosion

The Temporary Erosion and Sediment Control plans will include the following practices to reduce impacts on soil and vegetation in the project area:

  • Marking sensitive and vegetation-protection areas with high-visibility fencing.
  • Installing silt fencing where needed to reduce sediment from entering nearby water bodies.
  • Temporary and permanent seeding, plastic covering, and erosion-control fabrics and matting to protect vegetation and reduce erosion.

Over-water and in-water work (boating restrictions)

A crane operating over water.

What to expect during construction

Construction of a new eastbound bridge (the West Approach Bridge South) will require an extensive amount of in- and over-water work. Temporary work bridges and barges are used to complete removal of the old bridge and install the drilled shaft foundations, bridge columns and bridge deck in and over Lake Washington.

Construction commitments

WSDOT and the contractor will adhere to all WSDOT, federal, local, and statewide permits and approvals, including, but not limited to:

  • Section 401 and 404 of the Clean Water Act
  • Hydraulic permit approval
  • Coast Guard permit requirements
  • Seattle shoreline permit

Construction practices to minimize effects when working over or in the water

In addition to requirements of the permits listed above, the design-builder will prepare a Water Quality Monitoring and Protection Plan which outlines a number of best management practices, including:

  • Having spill-response kits and containment booms onboard barges and vessels.
  • Providing containment and/or covering for fuels, concrete, concrete process water, stormwater runoff, construction materials and debris.

Boating restrictions - ensuring the safety of watercraft users on Lake Washington.

To receive updates about boating activities and navigation restrictions on Lake Washington, email us at and ask to be added to the boater-notification list. Notification emails will be on an as-needed basis.

To stay safe around over-water work trestles, barge-mounted cranes and other heavy equipment, boaters, canoeists and kayakers should stay at least 100 feet away from all in-water construction equipment and structures.

Kayak/canoe access during construction

Kayak and canoe route during construction.

This map shows the off-limits areas for watercraft during construction of the SR 520 Montlake Project.

During Montlake Project construction, one navigation channel under the SR 520 bridge may be blocked periodically for critical construction work. During these blockages, marine vessels should plan to navigate through the unaffected channel (see below for navigational height restrictions). At least one branch of the navigation channel at the west end of the floating bridge will always be open and accessible to boaters. The navigation channel at the east end of the floating bridge will not be affected by the Montlake Project.

Navigation changes on Lake Washington along SR 520

Update: Both navigation channels open to boaters

Graphics showing the navigation channels immediately east and west of the 520 floating bridge. The clearance on the west side is shown as 47 feet. To the east, it's 65-70 feet.

The locations and clearance heights of the SR 520 floating bridge navigation channels.

Construction staging and haul routes

A truck hauling an oversized load.

What to expect during construction

The contractor will stage equipment and materials both on land and on barges near the construction areas. Staging areas will vary in size and function but will be available for use by the contractor 24 hours per day, 7 days per week. In order to build the new eastbound bridge, the Montlake Project contractor is building a temporary work bridge. The "WSDOT Peninsula," next to the Washington Park Arboretum, is the primary staging area during Montlake project construction, though other staging areas also are used. There will be additional staging locations under and near I-5 for the SR 520/I-5 Connection project (see maps below).

The contractor will use I-5, SR 520 and city arterials as haul routes for construction vehicles during SR 520 construction (see maps below).

Construction commitments

  • WSDOT and the contractor will adhere to all WSDOT, federal, local and statewide regulatory requirements and/or as required by the contract.
  • Additional Section 106 coordination will be required if the contractor proposes the use of haul routes outside of those previously identified in the Section 106 Programmatic Agreement (PDF 3.9MB) coordination process.

Construction practices to minimize the effects of staging and haul routes

SR 520 project contractors will work to limit the community effects of hauling and staging construction materials with actions such as:

  • Locating construction sheds, barricades and materials storage, where practicable, away from private properties, and not obscuring the views of and from private properties.
  • Where practicable, installing temporary construction screens/barriers, such as plantings or fencing, around construction areas to limit the visual effects of construction activities on private properties. The location and type of screens/barriers is determined in consultation with adjacent property owners.
  • Where practicable, avoiding placement of temporary work bridges and other short-term construction features where they would require permanent removal of mature trees or would damage them.

Anticipated Montlake Project construction staging areas

Map showing construction staging areas in the Montlake area

Haul routes and staging areas for SR 520 Montlake Project

Haul routes map

SR 520/I-5 Connection Project construction and staging areas

Project Construction and Staging Areas map

SR 520/I-5 Connection Project construction access and haul routes

Construction Access and Haul Routes map

Key construction-related management plans

Our community construction management plans (CCMPs) outline how the public can provide ongoing input into construction decisions that help to avoid, reduce or mitigate the effects of construction activities on historic properties and other neighborhood residences and businesses. The plans also guide the actions of our hired construction contractors, describe best management practices they are to follow, and provide opportunities for WSDOT to keep the public informed and gather input that improves our construction practices.

Click on the links below to read key SR 520 construction management plans and agreements: