It was a world’s first for one of Sound Transit’s Link light rail trains that will soon be regularly zipping into Mercer Island from across the Interstate 90 floating bridge.

For the first time worldwide in the morning hours of Sept. 8-9, a powered light rail vehicle traversed a floating bridge.

“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,” reads a Sound Transit Platform blog post. “These tests represent a big step forward for the 2 Line’s Crosslake Connection between Seattle and the Eastside.”

Sound Transit said that testing will continue between the Mercer Island and Judkins Park stations intermittently throughout the coming weeks.

“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,” the blog reads.

According to a Reporter story last May, Link light rail is now trending to open for service on Mercer Island in early 2026.

The first in a series of tests to connect East King County to Seattle occurred on May 21 when Sound Transit pushed a test train across the I-90 bridge from Mercer Island to Seattle.

The Mercer Island Station will be one of the segments of the 14-mile East Link Extension Project. The MI Station platform level distance is marked at 380 linear feet between the 77th Avenue Southeast entrance and the 80th Avenue Southeast entrance. Users will descend 27-foot staircases to the rail platform as reported in a Reporter tour on May 1, 2023.

Due to issues that arose in 2022 with the cast-in-place concrete plinths that support the tracks, the original projected East Link opening of mid-2023 was delayed, according to a previous Reporter story. The construction challenges also caused delays in the opening of other cities’ routes.