I-90 nighttime construction begins as early as May 29

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Crews working for Sound Transit will begin overnight work on the I-90 floating bridge to prepare for post-tensioning work inside the pontoons. As early as Tuesday, May 29, for approximately three weeks, work will occur nightly from 5 p.m. until 5 a.m., Monday – Saturday. Crews will install steel tendons which will be used to post-tension the pontoons later this summer. Work will begin on the west side of the bridge, near Seattle, and will proceed east.

Post-tensioning is a method of reinforcing concrete with high-strength tensioned steel strands. Essentially, compressing concrete and pulling the floating bridge pontoons closer together, increasing the bridge’s lifespan. In June and July, crews will post-tension the Homer M. Hadley Bridge, which will require overnight westbound closures. More information about these closures will be available in the coming weeks.

Here's what you can expect:
  • Crews will work from 5 p.m. – 5 a.m. Monday-Saturday. (Work hours are subject to change)
  • Crews will install steel tendons inside the floating bridge pontoons. Ballast may also be removed or added to the pontoons during this time.
  • Broadband back-up alarms will be used to minimize noise.
  • Generators and lighting may be used and will be shielded to minimize noise and glare.
  • Work activities will be monitored to comply with City of Seattle noise ordinances.

I-90 bridge construction map.