Skip to Content
Streetsblog USA home
Streetsblog USA home
Log In
Highway Expansion

Traffic Plummets on the Highway Seattle Is Spending a Fortune to Replace

Traffic has collapsed around Seattle's Alaskan Way Viaduct. Image: Sightline
Traffic has collapsed on Seattle's Alaskan Way Viaduct. Image: Sightline
Traffic has collapsed around Seattle's Alaskan Way Viaduct. Image: Sightline

For months now, the largest tunnel boring machine in the United States has been broken down under the city of Seattle. Meanwhile, traffic on the highway that the tunnel is supposed to replace has plummeted, raising more questions about whether the project is worth the enormous expense.

The project to replace the Alaskan Way Viaduct with a buried highway in Seattle is off to an absolutely disastrous start. Image: Wikipedia
The project to replace the Alaskan Way Viaduct with a buried highway is off to an absolutely disastrous start, but there's also a big upside to the new traffic patterns. Photo: Wikipedia
The project to replace the Alaskan Way Viaduct with a buried highway in Seattle is off to an absolutely disastrous start. Image: Wikipedia

The state of Washington intends to spend $3.1 billion to replace the Alaskan Way Viaduct -- an elevated double-decker highway right by the waterfront -- with an underground highway tunnel. But Bertha, the tunnel boring machine, is stuck a thousand feet into its path and will take months to get running again, if the state can get it running again at all.

Meanwhile, Clark Williams-Derry at regional think tank Sightline has made an amazing discovery: Traffic on the viaduct has plummeted by 48,000 vehicles per day in the last three years, or 44 percent, raising questions about whether this awesomely expensive undertaking is needed at all.

The reason for the traffic drop? A lot more people are taking buses. Some have avoided driving because of construction delays. Of those who are still driving, some have shifted to surface streets. Combine that with the fact that, across America, driving is declining in general -- and maybe Seattle doesn't need to replace this highway after all.

Williams-Derry puts it like this:

Nobody knows if Bertha will ever get moving again, let alone complete her job. But given these figures, maybe it doesn’t matter. Seattle has seamlessly adapted to losing the first 48,000 trips on the Viaduct. No one even noticed. No one even noticed that 40 percent of the Viaduct’s traffic just disappeared! Could accommodating the loss of another 62,000 be that hard if we, I don’t know, tried even a little?

Stay in touch

Sign up for our free newsletter

More from Streetsblog USA

Friday Video: The Fight to Expand A South Carolina Freeway … For Bikes

Greenville is looking for the good kind of induced demand — by expanding a popular rail-trail.

January 23, 2026

Friday’s Headlines Pollute All They Want

If the courts and Congress won't do it, the EPA under President Trump will just have to repeal itself.

January 23, 2026

Talking Headways Podcast: A Week Without Driving

Anna Zivarts discusses the lessons of her national campaign and yearly event with several politicians who brought it to their communities.

January 22, 2026

Aisle Be Damned: Dems and GOP Unite in Oregon In Bid To Legalize Kei Trucks

Tiny trucks bring people together across the political spectrum — and they could help save lives and budgets.

January 22, 2026

Thursday’s Headlines Are Getting Their Butts Kicked by China

China alone accounted for 72 percent of the new metro and light rail lines that opened last year, more than doubling the rest of the world combined.

January 22, 2026

Survey: Most Americans Are Open To Ditching Their Cars

Automakers have spent a century and countless trillions of dollars making car-dependent living the American norm. But U.S. resident still aren't sold, a new survey suggests.

January 21, 2026
See all posts