Bellevue commuters riding the 2 Line across Lake Washington have been traveling at reduced speed since the line opened in March. Sound Transit used an Oct. 17–18 weekend shutdown to begin repairs.

Electric arcing between overhead power rails and trains appeared during high-speed test runs last winter inside the Mercer Island tunnel, as The Seattle Times first reported, citing Sound Transit spokesperson Henry Bendon.

The agency capped speeds at about 40 mph through that stretch rather than the intended 55 mph. The slower speed added less than one minute to cross-lake trips, Bendon said.

Sound Transit opened the cross-lake and Mercer Island tracks on schedule March 28 despite the anomaly.

Seven months later, crews spent the weekend installing additional supports for overhead power rails attached to the underside of the Mercer Island lids, the covered sections commonly called tunnels. The power rails serve the same purpose as the overhead catenary wires used elsewhere in the Link network.

"We would like to get the speed back up to a full 55 mph," Bendon said. He cautioned it will probably take one more weekend of work to finish the job.

What riders faced Oct. 17–18

The 2 Line was suspended between South Bellevue and International District/Chinatown stations all day Saturday, Oct. 17, and Sunday, Oct. 18, according to a Sound Transit service notice. Shuttle buses ran every 10 to 15 minutes through the 8-mile closed corridor, stopping at Mercer Island and Judkins Park stations.

Service between Downtown Redmond and South Bellevue ran as scheduled. The 1 Line operated every eight minutes to absorb displaced riders heading north toward Lynnwood or south toward SeaTac and Federal Way.

The transit shutdown overlapped with a full northbound closure of Interstate 405 in downtown Bellevue. The Washington State Department of Transportation closed all northbound lanes between the Southeast Eighth and Northeast Fourth Street interchanges from 11 p.m. Friday, Oct. 16, through 4 a.m. Monday, Oct. 19, for ongoing toll-lane expansion work between Bellevue and Renton.

What comes next

Sound Transit has not announced a date for the second weekend of repairs.

Riders heading across the lake should watch for another service disruption in the coming weeks. If the reinforcements work as planned, trains through the Mercer Island tunnel would return to 55 mph.