Million dollars a minute? Traffic light syncing comes to the ‘Mercer Mess’

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SEATTLE — Thanks to some sensors, algorithms, and a little helping touch of the human hand, the Seattle Department of Transportation hopes to make the mania on Mercer Street in South Lake Union a little easier to handle. But it comes at a price.

“Still takes longer than anyone would like, I suspect,” said SDOT Director Scott Kubly.

While construction is long finished, the backups have stayed around. SDOT is now into week three of an adaptive lighting system with sensors and cameras at key intersections from 3rd Avenue all the way to Interstate 5.

Data is showing a better sync between lights helping the flow of cars on Mercer and other nearby streets.

“Now they’re adapting day to day, minute to minute, second to second,” Kubly said.

The nimble coordination is paying off, in a way.

Kubly said the trip eastbound from Queen Anne to the highway is, at most, three and a half minutes shorter.

But the syncing system cost nearly $4 million.

That's more than a million dollars a minute.

“It's three and a half minutes for thousands of people a day for hundreds of days a year,” Kubly said of the time savings. He added that the peak changes will save each driver nine hours a year.

“Mathematically, it's impossible to serve everyone efficiently. We have to choose,” said University of Washington researcher Mark Hellenbeck, who is cautiously optimistic of SDOT’s program.

He says getting the lights to talk to each other and work together is fantastic. But there's still a problem a light can't solve:

All of us in our cars.

“It's still going to be ugly because there's only so much,” he said.

The runaway growth in South Lake Union is the largest issue. Hellenbeck and SDOT do agree that the area is essentially at the saturation point for cars.

A trim of a few seconds here and there with lights is about all we can expect if people still drive.

“Ideally what we have is as we grow, more people walking, biking, taking transportation,” Kubly said.

SDOT is hoping for more funding on the syncing system so it can expand to Denny Way and the core of South Lake Union.