For three months now, motorists have been trying the Highway 99 tunnel, where their former viaduct views of Puget Sound were replaced by green-on-white stick figures, running toward the tunnel’s emergency exits.

The loss of scenery isn’t driving people away.

Traffic volumes have gradually increased since the tunnel’s opening day on snowy Feb. 4 to an average 74,900 weekday trips May 6-10, according to the latest state data. That’s approaching the roughly 80,000 weekday trips on the Alaskan Way Viaduct from 2011-18, when the tunnel was being built.

So basically, the tunnel is serving its traffic purpose, to continue to carry cars that bypass downtown.

Traffic Lab is a Seattle Times project that digs into the region’s thorny transportation issues, spotlights promising approaches to easing gridlock, and helps readers find the best ways to get around. It is funded with the help of community sponsors Madrona Venture Group and PEMCO Mutual Insurance Company. Seattle Times editors and reporters operate independently of our funders and maintain editorial control over Traffic Lab content.

As many as 13,000 drivers per weekday take the southbound Denny Way exit into downtown at South Lake Union instead of entering the tunnel, and 12,000 more take the First Avenue South exit instead of entering the tunnel northbound at Sodo.

Put all the numbers together, and the $3.2 billion project “is in the ballpark” of highway use in recent years, said Bart Treece, spokesman for the Washington Department of Transportation (WSDOT) traffic control center in Shoreline.

But there are problems, including an awkward lane layout on Aurora Avenue, speeding inside the tunnel, and a slow bus detour through First Avenue South. Transit used to roll on the viaduct until Seneca Street.

Traffic isn’t the only thing that matters. Many citizens, including former Mayor Mike McGinn, say the state blew a chance to eliminate Highway 99 altogether, for the sake of reducing fossil-fueled driving that contributes to climate breakdown. They cite a full three-week closure in January, when 90,000 trips around the region disappeared as people telecommuted, rode transit or biked.


The Seattle area avoided gridlock during the closure, and Aurora Avenue flows actually improved. But commute drivers in Federal Way had to depart before 6 a.m. to avoid congestion on northbound I-5, while delays worsened for general traffic in the West Seattle Bridge corridor.

The tunnel’s busiest day was Friday, April 19, though there was no Mariners baseball game or Sounders FC soccer match. It was the Friday before Easter Sunday, so people may have driven to the airport or state ferry terminal to travel to visit relatives.

“I think it’s working beautifully,” said former City Councilmember Tom Rasmussen of West Seattle, who uses the tunnel five days a week. “People have told me they’re really pleased and surprised at how well it’s working.”

To be sure, the double-deck tunnel with two lanes each direction doesn’t match viaduct capacity in its pre-2011 heyday, when three lanes ran each direction. Traffic averaged 105,000 trips then. In 2011 the state narrowed the viaduct to two lanes each direction at the south end, to make room for the launch of tunnel-boring machine Bertha.

More-frequent buses, in their own 40 mph Sodo lane, also attracted riders who shifted their commutes.


Former Gov. Christine Gregoire, who chose the deep tunnel option in early 2009, said it’s been safe and well used, though people sometimes complain to her the tunnel didn’t solve congestion.

“It was never intended to do that,” she said. “It was always intended to be a replacement for a very unsafe structure and a structure that divided the city from its waterfront.”

Tunnel patronage is nowhere near the 97,000 figure in a recent state toll-division forecast that leaned on mathematical models, and on a presumption that its new interchanges would encourage tunnel driving. The state’s consultants also predicted 44,000 tunnel trips will divert to streets or go away once the tunnel is eventually tolled — also a debatable number, given years of planning to keep rates down.

WSDOT is reluctant to draw conclusions about the tunnel after the first 13 weeks.

“This is just a moment in time, and there’s still changes coming to how people get around in Seattle,” said Treece. He said the “new normal” won’t arrive until 2023, when waterfront redevelopment and light rail to Bellevue are completed, ending the so-called Seattle Squeeze.

Hot spots have moved. Morning drivers are more likely to hit the brakes inside the tunnel, instead of on the West Seattle Bridge. For some the tunnel’s new Sodo interchange adds travel options northbound.


Drivers routinely speed 15 mph or more over the tunnel’s 45 mph limit. The tube has no speed-enforcement cameras and nowhere for police to park their vehicles in a speed trap.

“If you have an accident in there, it’s going to be very serious,” Rasmussen said.

People walking and bicycling remain at risk from drivers who turn onto Dexter Avenue North as they pour out from the northbound Mercer Street exit, Rasmussen said. Safe-street advocates pleaded with the city to ban right turns on red lights, while the Seattle Department of Transportation said it continues to monitor conditions.

Another shortcoming is the southbound approach from the Aurora Bridge, where morning traffic routinely snarls two miles up from Denny Way, sometimes reaching Woodland Park. The E Line bus and others use a right-side bus lane after the bridge, but transit operators must eventually merge across two crowded lanes to exit at Denny.

Motorists are sometimes perplexed by WSDOT’s yellow “Exit Only” sign in the left lane, that appears just beyond the Aurora Bridge. With the left lane marked for the Denny Way offramp, that leaves only the center lane designated for tunnel users, while the right lane is marked for buses.

Some people drive the bus lane at 35 mph pretending they’ll turn right, but then veer left shortly before Mercer Street, in front of other drivers who waited in the lineup.

Sue Williams, who drives from Queen Anne Hill to Normandy Park, said she’s seen another ruse, typically around 3 p.m., when a few drivers roll in the left-side Denny Way exit lane, then swerve right just before two slower lanes enter the tunnel.

Despite that complaint, she says, “I can’t say it’s worse than the viaduct,” Williams said.


WSDOT’s Treece said drivers are still experiencing “a learning curve,” and no immediate adjustments are planned by the state and city.

The next change is tolling, expected to begin in late summer.

Since May 1, some 14,000 drivers have obtained Good-to-Go windshield transponder stickers for free, in a temporary WSDOT promotion that waives the $5 fee, said Heather DeRosa, spokeswoman for the WSDOT toll division.

Toll rates will vary by time, from $1 minimum to $2.25 in afternoon peak times. The challenge will be collecting enough toll money to pay off $200 million that lawmakers demanded, while not diverting so many drivers that downtown gridlock worsens.