Attractions include free public walks, a paid bicycle ride and an 8k run along both the viaduct and tunnel. There will be children's science activities, musicians and food trucks at each end.

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Crowds of 50,000 people or more are expected to say goodbye to the Alaskan Way Viaduct and hello to the Highway 99 tunnel during weekend events Feb. 2-3.

Attractions include free public walks, a paid bicycle ride and an 8k run along both the viaduct and tunnel. There will be children’s science activities, musicians and food trucks at each end.

The viaduct closes permanently Jan. 11. The party falls three weekends later, when connecting ramps to the tunnel are finished. Tunnel traffic will start during the week following the party, about the same time major deck demolition of the viaduct gets started, said Dave Sowers, Highway 99 deputy administrator for the Washington State Department of Transportation (WSDOT).

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“Maybe up to 100,000 people could attend” the Highway 99 events, Sowers said. WSDOT asks revelers to reserve entry times at, to spread throngs evenly.

That’s one lesson from the Highway 520 floating bridge completion party on April 2, 2016. On that day, an afternoon sunbreak drew crowds that overwhelmed shuttle buses and filled the University of Washington light-rail station, and WSDOT stopped allowing people onto the bridge at midafternoon.

Highway 99 events ought to exceed the 40,000 to 50,000 visitors at the Highway 520 bridge because the tunnel is downtown near more people, with more events and more ways to get there, said Steve Peer, a WSDOT spokesman for Highway 520 projects.

The viaduct’s allure is well-established. Back in October 2011, a commemorative walk attracted 3,200 people to watch the beginning of a nine-day demolition of the structure’s southern half. This April, 7,000 people joined a Cascade Bicycle Club ride on the viaduct and Interstate 5 express lanes, under drizzly skies.

February weather won’t be much of a deterrent to bicyclists, said Brent Tongco, marketing director for Cascade. “It’s truly a once-in-a-lifetime opportunity,” he said.

Saturday, Feb. 2, events include:

  • An 8-kilometer fun run and walk through the new tunnel, the viaduct and the old Battery Street Tunnel, at 7:30 a.m., sponsored by engineering firm HTNB. Registration fee is $35.
  • A ribbon-cutting ceremony with elected officials at 11:30 a.m. at the south portal, next to Royal Brougham Way South.
  • Life-size mural of tunnel-boring machine Bertha’s front end, and Lego model at the north portal, from 11 a.m. to 6:30 p.m.
  • Exhibits about the geologic formations along Seattle’s waterfront, and earthquake-safety technology, at Pyramid Brewery near the south portal, 11 a.m. to 6:30 p.m.
  • Free public access to walk the viaduct and the tunnel, between 12:30 p.m. and 6 p.m.
  • An art festival on the viaduct, near the Seneca Street ramp in mid-downtown.
  • Shuttle buses one-way only, from the south to the north portal, all day Saturday

On Sunday, Feb. 3, a 12.5-mile bike ride starts at 8 a.m. Shorter routes are available. Registration is limited to 10,000 riders, at $40 for ages 13 and over, and $20 for people 12 and younger.

Costs of the celebration will be covered by state taxpayers, private sponsors (including The Seattle Times), and event registration fees. WSDOT said it didn’t have a budget summary available Thursday.

Some 18 years after the Nisqually earthquake damaged the viaduct, public sentiment remains split over whether the 57 1/3-foot diameter tunnel — three years behind schedule and costing over $3.3 billion including surface roads — was a good choice. Highway opponents cite carbon reduction and transit as higher priorities. Some drivers fear gridlock because the tunnel lacks Belltown ramps leading toward Interbay and Ballard.

“The viaduct has served this region remarkably well, and it has reached the end of its useful life,” said Marshall Foster, Seattle’s director for waterfront projects. “With its removal we have the opportunity as a region to reclaim 20 acres for parks and public spaces, and critical infrastructure.”