Drivers Ordered to Slow Acceleration Following Outages

Link Light Rail Credit: Lizz Giordano

Link Light Rail operators have been given orders to slow accelerations to reduce stress on the system after an electrical failure at the Tukwila International Boulevard Station substation Tuesday resulted in a power outage to the southern portion of the Link light rail system, according to Sound Transit.

On Tuesday a "major electrical substation failure" at the Tukwila Station suspended service between Othello and Angle Lake stations for approximately six hours. A bus bridge, which had as many as 36 shuttle buses running during its peak, transported riders until service resumed around 4:30 pm.

Earlier on Tuesday, trains were also stopped at the Mount Baker Station "after a unit along the trackway that sprays lubricant caught fire," according to Kimberly Reason a spokesperson for Sound Transit. The fire was quickly extinguished.

At this point, Sound Transit hasn't been able to determine the cause for either service disruption on Tuesday.

While there is no obvious connection between the two events, "given the unusual nature of these events and the proximity of the lubrication unit to elements of the traction power system, we have not ruled it out," Reason wrote in an email.

Sound Transit is also investigating if the substation failure at Tukwila is related to Sunday's two-half hour outages at Angle Lake. But damage incurred during the Tukwila substation failure has complicated the investigation.

"Our diagnostic challenges are compounded by the fact that the Tukwila failure caused major damage to the breaker and control system, destroying wiring and all equipment with memory that might have provided information about the events leading up to the failure," Reason wrote in an email.

According to Reason "service was restored after staff completed work to allow use of the Tukwila substation as a tie switch rather than as a power source, enabling power to be fed from other substations."

Sound Transit said slow orders to operators will reduce voltage spikes and stress on the system and will continue as the investigation moves forward and permanent repairs are made.

Reason said the work underway includes consulting with both the electrical system designer and the equipment manufacturer. She said at this time it is unknown if the high temperatures played a role in the outages.

Addressing the Capital Committee Thursday, Peter Rogoff, Sound Transit CEO, said orders to operators to slow accelerations was done as a precaution.

"These slow orders, fortunately, will have minimal to no impact customers and travel times," Rogoff said. "Redundancy is going to be built into all of these systems, but most importantly we need to get to the root cause of this problem, especially if it was related to the Sunday outages which means we are having a pattern rather than a one off."