Overview

Contractor crews replaced 32 of the 108 steel anchor cables on the Interstate 90 floating bridges on Lake Washington, between Seattle and Mercer Island. The cables stabilize the bridges and help keep them in place. 

The cables must be replaced every 25 to 30 years to maintain the safety and integrity of the bridges. The cables are subjected to years of pressure and stress from wind, waves, currents and changing traffic loads. Over time, the cables corrode, rust and fray. Most of the 32 cables that were replaced in this project were installed between 1983 and 1991. They range in length from 335 to 745 feet. Laid end to end, 15,630 feet of cable will be replaced, or just shy of three miles.

Needs & benefits

• Preservation: Replacing anchor cables on a regular basis preserves the structural integrity of the bridges, stabilizes the bridges during storms and ensures the safety of the 132,000 commuters and freight traffic who use I-90 to cross Lake Washington each day.
• Traffic: Worn cables pose a higher risk of snapping during a windstorm, which could lead to a long-term closure of the bridges, disrupting traffic for the thousands of drivers who use the bridges every day.
• Economic: Replacing cables on a regular basis ensures that the bridges remain open. It is an important link to the Port of Seattle, downtown business areas and the Interstate 5 corridor. An unexpected closure of the floating bridges due to cable damage or failure will disrupt the Puget Sound economy as commuters and freight are delayed reaching their destinations.

Funding

• The total estimated cost for this project is almost $8 million.
• The project was paid for using pre-existing funds.