Sound Transit I-90 Floating Bridge Stray Current and Corrosion Monitoring

Sound Transit is undertaking a decades long project to expand light rail service in the Seattle region, adding nearly 100 miles of track in the next 20 years. One of the new sections will be across the I-90 floating bridge between Seattle and Bellevue. This will be the only place in the world that light rail track has been installed across a floating bridge and it brings substantial engineering challenges. One of those challenges is electrically isolating the rails from the bridge so that the electrical current powering the trains doesn’t ‘stray’ off the tracks. Stray current can cause serious corrosion issues on the bridge, its pontoons, and nearby buried or submerged utilities.

Our corrosion engineering team is currently providing design review and will perform installation supervision, and commissioning testing of the bridge’s Stray Current and Corrosion Control Remote Monitoring (SCCCRM) system. In addition, we will provide training for Sound Transit personnel and work with the systems integration contractor to ensure that the SCCCRM system works properly with the Washington State Department of Transportation SCADA system.