Construction alert: Mercer Island Station

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Construction alert

Nighttime Construction on Mercer Island

Sound Transit’s contractor, Kiewit-Hoffman, has received a Construction Noise Exception from the City of Mercer Island to allow for certain construction activities to occur during nighttime working hours (7 p.m. – 7 a.m.) and Sundays. Nighttime Activities are anticipated to begin as early as October 4th, 2022

You are receiving this notice as you have been identified as a resident or property owner located near the work areas. This notice provides information about the types of activities, work hours and what you can expect as work begins. This notice complies with City of Mercer Island requirements.

Why perform the work at night?

  • Reduce traffic impacts: Crews must work at night to minimize daytime gridlock caused by working on this key commute and freight route. Working at night expedites completion of the project, allowing commuters and freight to quickly return to normal traffic patterns.
  • Safer work environment: As track mitigation work continues, the already narrow work zone footprint will continue to decrease and become crowded with crew members. By working at night, crews can work more hours and reduce the potential hazards caused by a crowded work zone.
  • Minimize delays: Sound Transit is dedicated to delivering a safe and reliable transit solution as soon as possible. By working at night crews will be able to complete work sooner, allowing for the opening of the new East Link Extension.

How long is work anticipated to last?

The noise exception is valid till May 31, 2023. Work is permitted to occur during overnight hours, from 7 p.m. – 7 a.m. Work may occur during non-consecutive nights and work may not occur at all locations every night. Kiewit- Hoffman may apply for future noise exception extensions as work progresses.

Where will work occur?

Work activities will primarily be located at three work zones on Mercer Island along the I-90 corridor. These locations include:

  • 60th Ave SE & I-90 to Mercer Island Tunnel
  • Mercer Island Tunnel
  • 76th Ave to 77th Ave SE & I-90 (near East portal to Mercer Island Tunnel)
  • Mercer Island Station (77th Ave SE to 80th Ave SE & I-90)
  • Frontage Road & I-90
Construction impacts map for Mercer Island Night work, East Link Extension

What types of work activities will occur?

Approved work activities were determined to have a low or medium potential to be a noise nuisance. Many of these activities produce sounds that fall below the existing I-90 nighttime noise levels. Impact activities such as jackhammering or pavement breaking, are not permitted at night.

Neighbors may hear construction vehicles, generators, track placement and welding activities. Approved work activities include:

  • Track Construction (Direct Fixation)
  • Bridge Retrofit Works, Floating Bridge
  • Bridge Survey
  • Traffic Control and Management of Traffic
  • Temporary Erosion and Sediment Control Best Management Practices (BMPs)
  • Security Fence Installation and Maintenance
  • Storm Water Management and Treatment Facilities

What is being done to mitigate the noise?

Crews will take several steps to minimize nighttime noise to the greatest extent possible:

  • Stationary equipment will be shielded using noise shields, blankets and skirts as necessary.
  • Trucks in the work zone will secure tailgates as necessary and will be equipped with ambient backup alarms, which are quieter than conventional alarms. Ambient back up alarms emits a white noise, hushing sound.
    Spotters may also be used.
  • The contractor will schedule work activities that may generate noise that is louder than I-90 vehicle traffic for early evenings when possible.

Construction noise and activities will be monitored and mitigation measures and construction techniques may be altered as necessary. Call the 24-7 construction hotline (888-298-2395) to speak to East Link Community Outreach staff or email

Stay Informed

Get project updates:

Sound Transit is committed to being a good neighbor during construction and works to manage impacts on surrounding communities.

We plan to provide notice of nighttime work via email and encourage you to contact Alison Tate,, Sound Transit Community Outreach, to be added to an email distribution list to receive the latest nighttime construction information.

More updates

Contact us

Community Engagement: or (206) 398-5300

Your safety is our priority

Learn how to stay safe around our construction sites.

Stay safe

24-hour construction hotline: 888-298-2395

More project info:
Get in touch: or (206) 398-5300