As Monday night stretched into Tuesday morning, Sound Transit celebrated a critical milestone as a powered light rail vehicle crossed the I-90 bridge between Seattle and the Eastside for the first time. The successful test, which followed an unpowered tow across the bridge in May, marks the start of the next phase of major prep work that will keep the full 2 Line on track for a grand opening next spring.
In view of a full throng of transit fans standing at Seattle’s East Portal Viewpoint, the single light rail train successfully traversed the Homer Hadley floating bridge and I-90 tunnel between Mercer Island and Judkins Park stations on its own power, then returned to Mercer Island. That low-speed trip was followed by additional trips that increased speeds up to 55 mph, the maximum cruising speed of Sound Transit’s trains.
Full analysis of the trips is still in progress, but all signs point to a successful set of tests that will keep the project moving forward, Sound Transit spokesperson Henry Bendon told the Seattle Times.
Sound Transit Board systems expansions chair Claudia Balducci of Bellevue was on hand to witness the moment. “It’s surprisingly exciting, for a 10 mph train trip,” Balducci told Mike Lindblom of the Seattle Times.
Live wire testing is especially important on a floating bridge. Sound Transit is seeking to demonstrate that its system to protect the bridge from stray current from light rail power systems is working as intended, preventing that voltage from corroding steel rebar and weakening the structure of the floating bridge or shortening its lifespan. Homer Hadley Bridge is intended to last 70 more years. Sound Transit officials said the system is performing as designed so far.
The pivotal section of track on I-90, a unique piece of infrastructure that automatically adjusts in response to the movement of the floating bridge, has proven the trickiest segment of the 2 Line to advance. In 2022, Sound Transit announced that defective plinths along the bridge would all need to be fixed, which resulted in several years of delays. The concrete plinths fasten light rail tracks in place.
A successful live wire test on the bridge was the culmination of years of work, work that started well before voters approved light rail to Redmond and Bellevue as part of the 2008 Sound Transit ballot package. In 2005, the Sound Transit and the Washington State Department of Transportation (WSDOT) tested how the bridge would perform with trucks weighed down by 600 tons of material to simulate trains. In 2013, Sound Transit shipped two track bridge prototypes to the Transportation Technology Center in Pueblo, Colorado, where more than 500 types of data were evaluated to ensure that the trains would be able to perform as expected on Lake Washington.
This week’s test follows months of work to calibrate around 300 electrical sensors up and down the bridge that ensure stray current from trains isn’t damaging the bridge structure below.
“It’s taking us a long time, longer than we wanted, partly because every time we make an adjustment, we need to wait two or three days for the system to stabilize, for us to take new readings, take more measurements,” Michael Morgan, the Executive Director for the East Link delivery team, told the Sound Transit board last month. “We’re taking our time. WSDOT has been super accommodating, super helpful in terms of this process, but we want to make sure everything is right before we put that first train on the bridge.”
Now comes 10 to 12 weeks of live wire testing, before the full 2 Line can enter pre-revenue service, which will entail another five-and-a-half months of testing. Amid assurances from Sound Transit CEO Dow Constantine that Sound Transit is set to beat the conservative estimated launch date of April 26, an early spring grand opening seems likely if all goes well.
One thing seems certain: the grand opening crossing the lake is surely the most highly anticipated transit launch in the region since the initial stretch of Sound Transit light rail opened in 2009. The initial Eastside-only 2 Line has already beat its ridership projections, showing robust demand for light rail connecting the Eastside.
“Around about midnight now we’re here at the Mercer Island portal to the I-90 floating bridge, waiting for the first train to cross under power,” Constantine said in a Sound Transit Instagram post recorded during testing. “I want to thank our entire East Link team, along with our partners from the Washington State Department of Transportation, everyone has made today possible. This is the first important step in our testing and ultimately training of our crews to get to passenger service across the I-90 bridge.”
When open, 2 Line trains will run from Lynnwood to Downtown Redmond, sharing tracks with the existing 1 Line as far south as International District-Chinatown. After getting trains running across Lake Washington, Sound Transit’s technical challenges aren’t finished, as it works to figure out how to increase system reliability along the existing 1 Line tracks.
A lack of crossover tracks, where trains can divert around trains stopped for incidents or technical issues, will likely increase the impact of disruptions once the agency starts running trains to Lynnwood every four minutes during morning and evening rush hour. Sound Transit has already said they plan to add a new set of crossover tracks somewhere in the Downtown Seattle’s transit tunnel, as part of a $5 billion package of operational investments that the agency will need to find a way to pay for.
With many Puget Sound residents wondering whether the day will ever come when Sound Transit started running trains across I-90, Monday’s late night test represents a victory for Sound Transit and for transit advocates across the region.
Ryan Packer has been writing for The Urbanist since 2015, and currently reports full-time as Contributing Editor. Their beats are transportation, land use, public space, traffic safety, and obscure community meetings. Packer has also reported for other regional outlets including BikePortland, Seattle Met, and PubliCola. They live in the Capitol Hill neighborhood of Seattle.
