Your Alaskan Way Viaduct and Highway 99 Tunnel Questions Answered

After 66 years, the Viaduct closes on January 11th...moving forward the new $2.2 billion smart tunnel is scheduled to open in early February.

The nearly two-decade-long effort to replace the Alaskan Way Viaduct hit a major milestone as it is replaced by the Highway 99 tunnel spanning Sodo to South Lake Union. The closure has undoubtedly caused concern and confusion for commuters and Seattleites alike, especially given that there will be an approximate three-week gap between the closure of the viaduct and the tunnel’s opening. Using research obtained by Seattle Times, let’s take a look at answers to some of the biggest questions surrounding the project.

What’s with the three-week gap?

According to Dave Sowers, the deputy Highway 99 administrator for the Washington State Department of Transportation (WSDOT), the tunnel is scheduled to open “sometime during the week of Feb. 3-9” because “contractors need time to pave new ramp connections from Aurora Avenue to the north tunnel portal, and from Sodo Highway 99 to the south portal. This work crosses highway lanes, forcing a full closure, along with traffic snarls entering central Seattle.”

How long will viaduct demolition take?

The viaduct demolition is slated to begin in January or February and will take—at minimum—four months to complete. This is due to the tight spaces surrounding the current viaduct, with as little as 10 feet between sidewalks and buildings.

What will the new tunnel look like?

As the Times outlines, there will be two southbound lanes on the upper level and two northbound lanes on the lower level, each measuring 11-feet wide. There will be an 8-foot shoulder on the waterfront side for emergency use, with a smaller 2-foot shoulder on the inner sides of the tunnel. “The posted speed limit is 45 mph, to be reduced by electronic lane signs when traffic is heavy,” the Times adds.

There will not be any direct downtown exits as there were on the viaduct, but there will be South Lake Union and Sodo interchange exits providing access to downtown Seattle.

Details for the $2.2 billion Alaskan Way (SR 99) tunnel's smart features (5 miles of electrical wiring; 21 miles of sprinkler pipes; 15 miles of lights; 13 miles of fiber optic cable and eight miles of linear heat detectors…)

How will the tolls work? Will they affect usage?

In order to give drivers time to adjust to the new tunnel, no tolls will be imposed until mid-2019. Once tolls go into effect, rates will vary by time of day, ranging from $1 during non-peak hours to $2.25 at the afternoon peak. In order to avoid the $2 surcharge per trip billed by mail, motorists will need to obtain a Good to Go pass for their windshield.

WSDOT research indicates that without tolls, the tunnel could serve 97,400 vehicles per day, a larger number than the 91,000 motorists that use the Alaskan Way Viaduct at its busiest point. Once tolls are charged, however, WSDOT says an estimated 44,000 drivers could elect to take alternate routes to avoid the fee.

What if I don’t want to pay the toll or use the tunnel?

The Times outlines a few alternate trip options for those that either don’t want to pay tolls or simply do not wish to drive in the tunnel, which include using the four-lane roadway on Alaskan Way along the waterfront or First and Fourth avenues. Each of these areas will see more traffic during the transition, without much relief expected “until waterfront bus lanes and increased Sound Transit light-rail capacity arrive in 2021.”

In celebration of the upcoming opening of the Highway 99 Tunnel, GeekWire  shared a time lapse video that spans six years and shows both the work on the tunnel and the evolving city skyline. In the background of the years-long SR 99 tunnel project work, “crane city is also hard at work and an evolving skyline takes shape. Specifically in the center of the frame, where Amazon HQ towers rise out of nowhere, starting in 2012,” GeekWire writes.


Though we are decidedly looking forward to an Alaskan Way Viaduct-free future, the Times  also took a moment to share the history of the viaduct, which opened to drivers on April 4, 1953.

The curving entrance, at left, to the viaduct from Battery Street is flanked by ramps from Elliott and Western Avenues on April 22, 1951. (Seattle Times archive)

The curving entrance, at left, to the viaduct from Battery Street is flanked by ramps from Elliott and Western Avenues on April 22, 1951. (Seattle Times archive)

As the Times outlines, “work on the viaduct began on Feb. 6, 1950 — a decade before Interstate 5 — with excavation at the north end at Battery Street and Western Avenue.” The five-part project culminated with a Saturday afternoon opening in which drivers traveled northbound, then turned around to head south once more.

Why did Seattle choose to move their highway from above ground to below ground? Watch video 👇