Late last Monday and into the morning hours of Tuesday, Sept. 8-9, the first Link light rail train crossed the I-90 Homer M. Hadley floating bridge across Lake Washington under its own power.
This momentous milestone marked the first time a powered light rail vehicle traversed a floating bridge, anywhere in the world.
Crews went on to repeat this landmark trip between Mercer Island and Judkins Park stations several times and at increasing speeds of up to 55 miles per hour.
These tests represent a big step forward for the 2 Line’s Crosslake Connection between Seattle and the Eastside.
After May’s tow test of an unpowered light rail vehicle across the bridge, these powered one-car train tests are the next step in comprehensive System Integration Testing, which lasts several months.
You can now expect to see trains on the floating bridge intermittently throughout the next several weeks.
But why do we conduct these tests while it’s dark?
Link trains draw power from an overhead contact system, and that means the potential for electrical arcing.
Arcing is power zapping between the overhead line and the train’s pantograph — the antenna-like arm connecting the vehicle to the wire.
Arcing is something we expect at this stage of progress, and the backdrop of darkness helps our crews observe and document it more easily, via a live video feed monitored by crews inside the train.
Any issues flagged during these overnight tests can then be addressed with adjustments during normal daytime hours, then we test again.
In the weeks since our May unpowered tow test, the East Link Extension has been hard at work preparing the floating bridge’s cathodic protection system to support an electrified train, as well as ensuring the track and overhead contact system were ready.
Last week’s results confirmed that the protection systems are performing as designed — preventing stray current or capturing it before it enters the bridge. We also validated that the overhead contact system interfaces correctly, at certain speeds, with a one-car train.
While this milestone is worthy of celebration, it’s also only one step in a months-long marathon of System Integration Testing. We have a lot of work ahead to deliver the 2 Line connection across the lake.
In the next few months, Sound Transit will perform testing with longer trains, finalize construction, train and qualify our operators, and stress-test our system, all leading up to the official opening for passenger service in 2026.
In the meantime, be on the lookout for trains on the bridge more regularly. This is an exciting visual cue that more light rail is coming soon to our region.
Stay tuned to The Platform blog and Sound Transit’s Instagram for every edition of the Crosslake Update!
