Construction Update: West Sammamish River Bridge Replacement Project


West Sammamish River Bridge Replacement Project Update


Why Replace the Bridge?

The 82-year-old west bridge (existing southbound) is near the end of its service life and is currently categorized as “Structurally Deficient,” with a rating of 6.45 out of 100. The current live loads (vehicles) and dead loads (bridge structure) on the bridge are greater than the bridge was designed for and the bridge is showing signs of deterioration such as cracking, leaching, and spalling. Replacement of the bridge is necessary for safety and to maintain 2 lanes of traffic in each direction across the river.

COVID-19 Impacts to Delivery Schedule

The delivery of girders, which are bridge support systems, has been impacted by COVID-19, requiring the City of Kenmore to consider alternate options to complete the project within environmental permit regulations. Two options were submitted to Council. Option 1 was to maintain traffic on both southbound and northbound bridges as originally planned. This Option would require an additional fish window and delay completion of the project for one year with an estimated additional cost of $2.5 million dollars. Option 2 would allow the contractor to close the southbound (west) bridge for 10 months in 2021, move all traffic to the northbound bridge and maintain one lane of traffic each direction. 

At the August 3 City Council meeting, Option 2 was approved by the Council. The Council also voted for additional improvements to the corridor which includes extending the northbound right turn lane from NE 175th Street to the north bridge abutment, a new sidewalk and a planting strip. There was overwhelming support for Option 2 by people who provided public comment and/or sent emails to the city.

What is Option 2 and what does it mean?

This means long delays will be the norm during this 10-month period, but there are also some advantages to this option:

  • Complete project without additional fish windows
  • Majority of roadway work completed in June 2022 versus the original schedule completing by September 2022
  • Approximately $500,000 in cost savings
  • Increased safety for workers and the public
  • Reduced environmental impacts
  • Reduced night work activity
  • Project completed on time and within budget

What is a “fish window?”

A “fish window” is a period of time defined by the Department of Ecology when in-water work is authorized. The fish window takes into consideration salmon migration and designates in-water work only during periods outside the migration season, for the protection of salmon and habitat. The fish windows are:

  • July 1 to August 31, 2020
  • July 1 to August 31, 2021
  • July 15 to August 31, 2022

What traffic mitigation is planned?

  • There will be uniformed police officers (UPOs) at the intersections of 68th Avenue NE/NE 170th Street  and 68th Avenue NE/NE 175th Street, Monday – Friday during working hours, when UPOs are available. (There are times when police officers are not available or need to leave for emergency reasons, and this may have a significant effect on travel times.)
  • Possible alteration in phasing of traffic signals.
  • Variable Message Signs (VMS) have been placed on SR 522 warning about delays and encouraging use of alternate routes.

The City is in the process of working out the specifics with the Contractor, Ceccanti, and more details will be available later in the year. The closure of the west bridge will not take effect until January 2021. In the meantime, work over the next few months will continue to prepare for demolition of the bridge, and there will be work on walls using geofoam (to fill voids and minimize settlement). There will also be utility work, joint utility trench, and irrigation systems work.

Hang in there – it will be worth it in the end!

The City understands that this will be a trying time for many. The City’s objective is to provide a safe, new bridge, a wonderful pedestrian promenade with 8-foot sidewalks and 8-foot bike path, new sidewalk along the east side of the corridor, new decorative street lighting, underground utilities, and a lot of new trees and landscaping to create a buffer zone and enhance visual appeal. Thank you for your continued patience as this important work is completed.

We are available to answer questions:

Website: Visit for current information
Phone: 24/7 project hotline (425) 201-4147
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