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9611 SE 36th Street
Mercer Island, WA 98040
Phone: 206.275.7600
Fax: 206.276.7663
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Bus and Rail Transit Interchange

The 77th Avenue SE Bus-Rail Configuration; click to enlarge (April 2017)


One of the remaining issues under discussion regarding light rail on Mercer Island is the way that the future system (opening 2023) will connect with existing bus transit at the Mercer Island Station. The objective of this effort is to identify opportunities to minimize overlap with existing bus routes along I-90, maximize transit efficiency and reduce air pollution, while protecting the quality of life for Island residents. Sound Transit and Metro plans call for most of the regional buses from the Eastside to terminate at the South Bellevue and Mercer Island Park-and-Ride facilities and transfer passengers to/from light rail that will serve Seattle. 

What's Happening Now

NEW: The City Council held two Study Sessions (19 March and 30 April, 2019) at which Sound Transit and Metro presented updates on roundabout design and proposed future bus operations. Meeting materials, FAQ, and comments/questions are available via the City's public engagement portal, Let's Talk Mercer Island.

When Council issued its final approval of a $10.1million mitigation package from Sound Transit on October 17, 2017, bus-rail integration planning and design resumed. The City Council was successful in ensuring that bus pick-up and drop-off activities would occur primarily at the current Park-and-Ride on North Mercer Way, with a turnaround at the 77th Avenue SE intersection. View a Sound Transit draft visualization of the roundabout here. King County Metro and local transit advocates are also partners in the planning discussions.

This concept replaces the more complex bus turnaround and pickup/dropoff facility area along 80th Avenue SE that was originally proposed by Sound Transit.

The 77th Avenue configuration means that:
  • Only local, and not regional buses, would drive through Town Center along SE 27th Street
  • Bus layovers will be limited in duration (approx 15 mins) and no diesel idling is allowed
  • Bus volumes along North Mercer Way will not exceed current volumes (excluding MI-only service)

Prior proposals for bus-rail integration facilities were all rejected by the City Council, due to ongoing concerns over lack of sufficient commuter parking for residents, local traffic impacts due to bus traffic, and general pedestrian, bicycle, and vehicle mobility impacts around the proposed bus drop-off location. Click here to view all past, abandoned proposals.

Get Involved

Please visit the City's public engagement portal, Let's Talk Mercer Island to view upcoming events and activities.


Submit Comments

Please visit the City's public engagement portal, Let's Talk Mercer Island to submit comments or questions.



  • October 17, 2017: City Council approves settlement package from Sound Transit, which also ensures that bus/rail operations will be focused at the Park & Ride on North Mercer Way, and not on 80th Ave.
  • May 11, 2015: Mayor Bassett transmitted a formal letter to Sound Transit indicating the full City Council's rejection of the Bus Intercept proposal.
  • May 1, 2015: Sound Transit letter responding to the City's memo.
  • April 20, 2015: The City met with Sound Transit and King County Metro and determined the current proposal could not be accepted by the City Council.
  • March 30, 2015: City memo regarding the Bus Intercept concept and Sound Transit funding update.  
  • June 16, 2014: Based on a Study Session presentation to City Council by Sound Transit and King County Metro, Mayor Bruce Bassett commented on the likely inadequacy of the proposal.

Additional Resources

Click here to read the East Link Bus/Rail System Integration study, July 2014 (6.5Mb)
The study developed various scenarios exploring a future interconnection between the Metro and Sound Transit bus systems with East Link light rail at the Mercer Island Station.

Click here to view the East Link Project Final Environmental Impact Statement, July 2011 (FEIS)
Note that previous work related to transit operations along I-90 and Mercer Island was completed as part of Sound Transitís East Link FEIS. For the purposes of the integration study, the East Link FEIS preferred alternative represents the baseline future condition; all of the findings associated with the bus/rail integration scenarios are compared back to this baseline future condition.

Click here to view the ​​SEPA Addendum to the East Link FEIS, April 2017
This document contains a section that addresses updated thinking around bus-rail integration.


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