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Project Details

I-405 Rolling Slowdowns and Fiberoptic Improvement

Posting Date: 9/8/2017                

Contact: Mark VanOss - Sr., Public Relations Specialist

Phone: 206-684-3279

PROJECT UPDATE (9/20/2017)

Crews completed the fiberoptic improvement work in two nights, so rolling slowdowns are no longer needed for the remaining days this week.


Seattle City Light crews plan to enhance the reliability of the electrical system by pulling in new fiberoptic cables across Interstate 405 approximately two miles southeast of Alderwood Mall.

To complete this work, crews must intermittently conduct rolling slowdowns of traffic in both directions of I-405 to ensure safe work operations and passage for motorists. The work will start on Monday night, September 18. Traffic will be intercepted and escorted at slow speeds for up to 15 minutes between just southeast of the I-5/I-405 interchange and NE 195th Street as crews install the new fiberoptic cable overhead across the highway. Traffic will return to normal speeds once past the work area. See the map for more details:

 This is a map of the rolling slowdown boundaries.

Drivers should expect delays and consider using alternate routes during construction.

Rolling slowdown details

Occurring nightly from 11:59 p.m. to 4 a.m. beginning Monday, Sept. 18 through the morning of Friday, Sept. 22: 

  • Washington State Patrol troopers and contracted crews will intermittently intercept and escort southbound I-405 traffic through the work area beginning southeast of the I-5/I-405 interchange. The same will occur for northbound traffic beginning at NE 195th
  • Traffic using the following on-ramps to I-405 will also be affected: I-5 northbound to I-405 southbound, I-5 southbound to I-405 southbound, NE 195th Street to northbound I-405, State Route 527 northbound to northbound I-405, and State Route 522 to northbound I-405.

Should the crews finish in less than four nights, City Light plans to communicate via social media and at this Website. 

Customers will benefit with increased electrical reliability. The new fiberoptic lines will provide redundant communication between facilities generating power at City Light's Skagit hydropower sites, the Bonneville Power Administration, and City Light substations and its system control center.


Construction Start: Monday, Sept. 18

Duration: Mon.,9/18 through the morning of Fri.,9/22

Daily Work Schedule: Occurring nightly from 11:59 p.m. to 4 a.m.

Alternate Contact: Scott Thomsen - Sr. Strategic Advisor

Alternative Contact Phone: 206.615.0978

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