It will take Sound Transit longer to finish construction work that has disrupted light rail service since January, meaning trains will continue to run at less frequent intervals.

The work, necessary to join existing light rail to a new line to the Eastside, has required trains to run on a single track through downtown, reducing light rail service to running about every 15 minutes.

Sound Transit identified issues while completing final systems testing over the weekend, the agency said Sunday.

The system of power that transfers between wires, tracks and trains was not insulated properly, which could result in signal problems and trains not running on time.

Sound Transit previously said the disruptions would last 10 weeks, which would have returned things to normal Monday.

For now, riders will have to continue to transfer trains at Pioneer Square Station and bikes will not be allowed into or through that station in an attempt to reduce crowding. It’s not clear when repairs will be finished.


In order to fix the problem, downtown stations will be closed on at least one weekend for retesting to certify the new tracks, though specific dates are not known.

“We regret this further inconvenience for our passengers, especially during this difficult time, and thank them for their continued patience,” Sound Transit CEO Peter Rogoff said in a statement.

Light rail service to the Eastside is expected to begin in 2023.