The Sound Transit 2 light rail expansion links Seattle and the Eastside and delivers first-of-its-kind floating bridge for light rail
SEATTLE (March 30, 2026) – HNTB joins Sound Transit and regional partners in celebrating the opening of the Crosslake Connection, the final segment of the 2 Line that links Seattle and the Eastside with light rail service across Lake Washington.
The Crosslake Connection introduces the world’s first light rail service operating on a floating bridge. The achievement completes the 2 Line and fulfills a key commitment of the Sound Transit 2 voter-approved expansion plan, connecting the 2 Line to the 1 Line at International District/Chinatown Station and linking Seattle and the Eastside by light rail across Lake Washington.
HNTB served as part of the construction management consultant team, providing resident engineers, inspectors, cost facilitators and other key personnel to support Sound Transit in delivering the connection.
HNTB’s Mark Holmes
“The Crosslake Connection reflects years of planning, innovation and coordination across agencies,” said Mark Holmes, vice president and group director of construction services and project controls at HNTB. “Serving as part of the construction management team, our staff worked alongside Sound Transit and project partners in a highly integrated, one-team structure to support delivery of this critical regional investment.”
Constructing the first-ever rail infrastructure on a floating bridge required innovative solutions that account for lake movement, weather and long-term durability. Beyond specialized track systems, a first-of-its-kind application of cathodic protection was installed to protect the concrete pontoons and post-tensioned steel anchor cables, preserving the structural integrity of the existing structures and supporting long-term reliability. The work also required careful integration of new tunnel fire and life safety systems with legacy infrastructure, coordinated across multiple jurisdictions.
The Crosslake Connection links Seattle, Mercer Island, Bellevue and Redmond, expanding access to jobs, education, healthcare and cultural destinations throughout the region. With the 2 Line fully operational, Sound Transit’s light rail network now spans 63 miles. Trains arrive about every eight minutes at the new stations during peak periods, with the 1 Line and 2 Line providing frequent service through the system’s central corridor.
“The Crosslake Connection represents years of dedication, persistence and collaboration,” said Tony Raben, executive project director at Sound Transit. “Designing and constructing light rail across a floating bridge required innovation and partnership at every level. This project delivers a connection that strengthens mobility and will serve riders across the region for generations.”
As part of its ongoing support for Link expansion across the region, HNTB also contributed final design services for the East Link Extension from South Bellevue to the Overlake Transit Center in Redmond, which opened in spring 2024, and provided project management leadership for engineering and architecture on the Lynnwood Link Extension from Northgate to Lynnwood City Center, which opened in 2024.