The State Route 99 on- and off-ramps at the stadiums closed last week, and the Seattle Squeeze officially starts when the Alaskan Way Viaduct closes permanently at 10 p.m. Friday.

While commuters moving between West Seattle, downtown and neighborhoods to the north want solid directions on how to proceed, there are no detours that will work for everyone. Regional transportation agencies have been encouraging drivers to wean themselves off the viaduct for months now, in anticipation of SR 99 closing for three weeks while WSDOT stitches the highway to a new two-mile tunnel from SODO to Seattle Center.

“The tunnel is, for the most part, done,” says WSDOT spokesperson Laura Newborn with the Alaskan Way Viaduct Replacement Program.

The Battery Street Tunnel will remain open through Friday, Feb. 1, at which point it will also close. Its last visitors will be those saying goodbye to the viaduct during a two-day grand opening celebration that will precede SR 99’s planned reopening on Monday, Feb. 4.

Once SR 99 is back online, the Alaskan Way Viaduct will come down, and the concrete and debris from its deconstruction will be used to fill in the Battery Street Tunnel. The viaduct is expected to take six months to remove.

Once the viaduct comes down, the City of Seattle can begin rebuilding a new Alaskan Way, which is slated to be completed in 2021 and complement a revitalized Seattle Waterfront.

While the city waits for the SR 99 Tunnel to come online, it will also be changing the way it manages public right-of-ways, which includes expediting permits to restore streets following completion of construction projects, modifying or revoking construction permits until congestion is alleviated, and deploying police officers to direct traffic at key intersections when issues arise.

After the closure

SDOT Downtown Mobility director Heather Marx says the first two days of these types of major closures are usually fine, and then “traffic rears its ugly head” when drivers become comfortable with the change.

Forty-eight percent of downtown commuters come into the city from 6-9 a.m., said King County Metro Service Development managing director Bill Bryant. During the SR 99 closure, he said, there will be 20 buses on standby downtown, ready to respond where needed. Between Sound Transit and Metro, transit will be slower.

“We ask, especially new riders, to be patient with us,” Bryant said.

During the SR 99 closure, drivers wanting to head north or south are encouraged to either use Interstate 5 or Western Avenue, said David Sowers, Alaskan Way Viaduct Replacement Program deputy administrator for WSDOT, when discussing the early closure of exits at the stadiums last week.

The closure of the viaduct is expected to move 90,000 vehicles onto other routes, including several thousand trucks and buses, and backups are expected on I-5 and other routes downtown. A real-time traffic map will provide information on where congestion exists and what routes are looking good at seattle.gov/travelers. Traffic projections, including best times to head out, will be updated at seattletraffic.org.

Vehicle activity is expected to increase north and south on Second Avenue, north on Fourth Avenue and south on Fifth Avenue. There will also be impacts from Third Avenue downtown now being transit-only from 6 a.m. to 7 p.m. every day, McCall said.

WSDOT will increase use of its I-5 active traffic management system, which includes the dynamic display signs that can adjust vehicle speed requirements to address congestion. There will also be added traffic cameras and monitoring devices.

SDOT upgraded its Transportation Operations Center to a 24/7 system in October, monitoring traffic flow around the city and deploying aid where needed; it had originally only operated from 6 a.m. to 10 p.m. daily.

From the Transportation Operations Center, SDOT staff can adjust traffic signal timing to address areas around the city experiencing increased congestion.

Following a three-year pilot program, the SDOT Response Team also became a 24/7 tool for clearing traffic impacts and keeping vehicles moving throughout the city, and can be deployed by staff in the operations center.

Those who can use third-party navigation apps, such as Waze and Google Maps, are encouraged to use these tools, as transportation agencies will be sharing travel data with these third-party applications.

Transportation system changes

As much as people may want to continue driving, transportation agencies are focused on reducing the number of single-occupancy vehicles on streets during the next four years of increased congestion from transportation and construction of major projects like the Washington State Convention Center Addition, which means prioritizing buses when the viaduct closes.

• Temporary transit lanes are being added on Cherry Street, the West Seattle Bridge, Fourth Avenue South and Aurora Avenue, and eastbound contraflow (bus and bike) lanes will be removed on Seneca Street.

• A transit and freight bypass between Alaskan Way and East Marginal Way will be opened.

• Traffic will be able to use the southbound high-occupancy vehicle (HOV) lane from Mercer to Corson streets during the closure.

• The Coast Guard also granted the city permission to expand hours when key bridges, such as the Ballard Bridge, are closed to mariners, “and it was a significant win for us,” Marx said.

Drivers can also expect to see on-street parking disappear along key arterial streets.

Bus impacts

Work on the north portal of the 99 Tunnel will impact buses using Aurora Avenue (routes E, 5, 5X, 26,28) and people should expect delays, Bryant said. South-end bus impacts from the viaduct closure include routes 21X, 37, 55, 56, 57, 113, 120, 121, 122, 123, 125 and the Rapid Ride C line, which will be diverted to First Avenue South for up to a year. A permanent south-end pathway will include the rebuilt Alaskan Way.

Transportation agencies are working with downtown employers that provide employee shuttle services, opening up specific loading zones and certain Metro stops for them to use that are not expected to complicate public transit, Marx said.

Plan B

Should the initial response not be enough to address increased congestion from the viaduct closure, a Plan B is in place that would include potentially increasing on-street parking restrictions, adding more transit-only lanes and operating certain streets as transit-only, and working with Metro to reroute transit to less congested routes. If that doesn’t provide enough congestion relief, WSDOT would likely modify the availability of I-5 ramps, SOV turns could be restricted downtown, transit-priority streets could be extended from 5 a.m. to 10 p.m., and the city would further reduce employee travel.

After the tunnel opens

The SR 99 tunnel will be a convenient way to get from Seattle Center to the north to the stadiums to the south, and free until sometime this summer.

Weekday tolls will be $1.50 from 7 a.m. to 9 a.m. (peak commute) and $2.25 from 3-6 p.m. (evening peak). The toll will be $1.25 during non-peak hours between 6 a.m. and 11 p.m., and $1 for weekend and overnight (11 p.m. to 6 a.m.) tolls. Anyone without a Good To Go! pass will pay an extra $2.

The Washington State Transportation Commission voted on the toll rates for the tunnel in October, which will increase by 3 percent every three years starting in July 2022.

WSDOT predicts more people will use the tunnel during peak hours than used the viaduct prior to tolling — up from 5,000 to 7,000. Without exits to Seneca Street and Western Avenue, there will be drivers who used the viaduct who will need to find other routes that work for them.

The number of drivers using the tunnel is forecast to drop to 4,000-5,000 vehicles per hour during peak periods once tolling starts, according to WSDOT.

Newborn says the tolled State Route 520 bridge started with a traffic decrease, and then grew later, which is what WSDOT expects with the SR 99 Tunnel.

There will be incident response trucks at either end of the tunnel at all times, Newborn said, the state transportation department controlling the tunnel system. Seattle firefighters and police will handle emergency responses as they do now in the Battery Street Tunnel.

While the viaduct is being removed, three blocks of Aurora Avenue North will also be rebuilt starting in February, reconnecting Thomas and John streets to the major arterial, which will take about 15 months to complete. Harrison Street is planned to be reconnected the same time the SR 99 Tunnel opens, and will have traffic signals. Southbound drivers on SR 99 can proceed to SODO or exit to Harrison, where a left takes them to South Lake Union, or they can make a right to head to Seattle Center or Queen Anne, or continue south to downtown.

However, the northbound off-ramp to downtown isn’t expected to open until about two weeks after the tunnel does.

The next big congestion nightmare will be when the Downtown Seattle Transit Tunnel closes to buses, pushing seven major routes — 15,000 daily riders — onto surface streets.

99 Step Forward

More than 40,000 people have signed up for the two-day Step Forward event that will lead into the grand opening of the SR 99 Tunnel, which includes an Tunnel to Viaduct 8K Run/Walk, a free two-mile tunnel walk, ribbon-cutting ceremony and celebration and art walk along the viaduct on Saturday, Feb. 2. A bicycle race will be held on Sunday, Feb. 3. More information is at 99StepForward.com. Fees for the races will be used to support the event, and WSDOT and agency partners have also lined up sponsors.