Streetcar stalls twice in 2 weeks; electrical system being fine-tuned

Seattle's South Lake Union streetcar has stalled twice during its first two weeks of service, prompting officials to make changes to the electrical system.

Streetcars stalled at 10:55 a.m. on Dec. 14 and at 5:30 p.m. Saturday, forcing passengers off the trains. The first outage lasted 37 minutes, and Saturday's incident lasted 1-¾ hours, said Marwan Al-Mukhtar, streetcar rail-operations chief for Metro.

Officials say the problem originates at the corner of Westlake Avenue and Stewart Street, where the streetcar's overhead electric wire crosses the power lines for King County Metro Transit's trolley buses.

When the charged pole of a Metro trolley bus gets close to the streetcar wire, a "pop" or flash can occur.

The resulting power spike can trip a circuit breaker and disrupt the streetcar's power supply.

And about once a day, one of the streetcar's two substations has tripped off momentarily but without interrupting train service, said Ronald Clark, a power-supply specialist for Elcon Associates, a streetcar consultant.

In those cases, he said, either the substation reset itself or trains drew enough power from the other substation.

The trains are proving popular, with nearly 3,000 boardings a day since service began Dec. 12, on the 1.3-mile route from the Westin Seattle Hotel to the Fred Hutchinson Cancer Research Center.

Rides are free through Monday.

When the streetcar was designed, officials recognized the challenge of running streetcars next to trolley buses.

"But frankly, you have a little bit of trial and error once you start testing and operations," said Ethan Melone, the city's streetcar-project manager.

To prevent power spikes, workers will add insulation to an aluminum frame that separates streetcar and bus-trolley wires, over the Stewart-Westlake intersection, Melone said.

Clark said technicians are adjusting the substations to reduce sensitivity to the power spikes. They can shut off now in less than one-tenth of a second.

"How can we set it so it's as safe as possible, and not cause nuisance tripping?" he said.

The goal is 100 percent reliability, Melone said.

"Things are getting fixed very, very rapidly. This is an issue, a month from now, people won't be talking about it," Al-Mukhtar said.

Similar challenges will arise if the streetcars expand to other corridors with trolley lines, such as Eastlake Avenue East, South Jackson Street or Broadway.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com