Bellevue 2 Line riders lost their downtown Seattle connection Saturday, Oct. 24, when trains turned back at Judkins Park Station, one stop short of the tunnel.

The turnaround was one consequence of six light rail suspensions over the Oct. 24-25 weekend, all traced to a single malfunctioning substation near Northgate Station in north Seattle, The Seattle Times first reported.

Service was blocked or slowed for a combined four hours across the system's busiest corridor, between Shoreline South/148th and University of Washington stations.

Sound Transit spokesperson Henry Bendon told the Times that software inside the Northgate substation detected a problem and signaled other substations to shut down.

That safeguard, called a transfer-trip, is meant to prevent equipment damage from power surges. But it also means one substation failure can halt trains across the network.

Bendon called the problem a "communication issue." Engineers are investigating, and Sound Transit has not set a timeline for releasing findings.

The breakdowns came days after CEO Dow Constantine told 375 people at a Ballard community forum that Sound Transit had "reduced unplanned disruptions, below even our most ambitious targets," according to the Times.

Constantine's stated goal was 10 or fewer hours of disruptions per month, down from an average of 36 hours per month in 2024. The Times reported that light rail averaged eight hours of monthly disruptions in the first four months of 2026.

Because Sound Transit routes all trains in its two-line, 58-mile system through the downtown Seattle tunnel, a power failure near the University of Washington can ripple across the entire network.

Eastside 2 Line trains were turned back at Judkins Park on Saturday morning to keep the tunnel clear, the Times reported.

Bellevue riders have seen this before. Two years ago, chain-reaction substation shutdowns blocked trains for hours near Spring District Station, prompting the agency to recalibrate equipment and speed up crew response times.

Breakdowns on Saturday, Oct. 24, hit at 9:34 a.m., 6:25 p.m. and 11:46 p.m. On Sunday, Oct. 25, problems struck at 7:35 a.m., 11:06 a.m. and 8:11 p.m., according to rider alerts cited by the Times.

Shuttle buses replaced trains at times, including during the Seahawks game Sunday night.

Technicians eventually isolated the Northgate substation so other substations could supply power without being tripped offline, Bendon said.

Separate, unrelated slowdowns also hit the 2 Line near Redmond around 12:30 p.m. Saturday, rider alerts showed.

Sound Transit's own July 2026 performance report, the most recent available, showed Link light rail hitting 86% headway adherence against a 90% target.

Power system availability fell to 89%, down from 93% the prior month. Both the 1 Line and 2 Line operated below the 98.5% "operated as scheduled" target.

Bendon told the Times the agency is developing new reliability metrics. The current "hours per month" measure does not account for when, where or how many riders a breakdown affects.

Link light rail now carries about 170,000 daily passengers, the highest ridership of any U.S. light rail system, the Times reported. The next investigation update has no scheduled release date.