UTRS client Sound Transit recently achieved key live-wire testing milestones on the world’s first floating railway bridge across Lake Washington, where we applied our expertise in cathodic protection to safeguard the structure against long-term corrosion. This innovative project is a critical component of Sound Transit’s East Link Extension, carrying light rail across the I-90 floating bridge – the first time rail has ever been installed over a floating span.
This groundbreaking achievement validates UTRS’s innovative cathodic protection systems, which were specifically engineered to address the unique challenges of protecting massive floating concrete pontoons from long-term corrosion while managing the electrical complexities introduced by high-voltage rail systems.
Proving the Power of Cathodic Protection
The successful powered testing, conducted at speeds up to the full operating speed of 55 mph, confirmed that UTRS’s state-of-the-art protection systems are performing exactly as designed – preventing stray current from entering the bridge structure and capturing it before it can cause accelerated corrosion of the pontoons’ steel rebar. Sound Transit’s recent update highlighted the critical importance of the cathodic protection system to the project’s success, noting that extensive preparation of the floating bridge’s cathodic protection system was essential for supporting the electrified train.
The project represents a convergence of UTRS’s deep expertise in both floating bridge protection and conventional transit system corrosion control. Building on our previous success with Seattle’s Evergreen Point Floating Bridge as well as transit infrastructure nationwide, UTRS engineered comprehensive responses to this unprecedented challenge. Our solution included specialized plinth insulation, environmental protection measures, and systems integration with the rail’s overhead contact system. UTRS’s design features an automated stray current detection system and a stray current collector system that work together to shunt stray current off the bridge and to a land-based discharge point.
Sound Transit has also shared additional details about the cathodic protection work on their Instagram channel, showcasing the technical sophistication required for this world-first application.
System Integration Testing will continue over the coming months with longer train configurations on this innovative infrastructure leading up to the official opening for passenger service in 2026. Successful testing represents validation of UTRS’s ability to deliver cutting-edge engineering solutions for the most challenging infrastructure projects.