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: Disney World Has Some of the Best Transit In America … If You Can Get There Without a Car

Two creators break down why there isn't a train or a bus to the happiest place on Earth — and why transit within the park's walls is so much better than many American cities.

May 2, 2025

Friday’s Headlines Keep Their Eyes on the Prize

Traffic engineers often think wide, straight roads are safe. Forget that. A few trees here, a few benches there is all it takes to make drivers perk up, slow down and pay attention.

May 2, 2025

Talking Headways Podcast: Behind the Mayor’s Desk

Anthony Flint of the Lincoln Institute of Land Policy shares a global perspective on mayors and the challenges that connect cities around the world.

May 1, 2025

The Highway Shakedown, Part Two: What Locals Lose When Road Funding Isn’t Distributed Fairly

While lawmakers fight to defend America's "user-pay" road funding system, both federal and state policies have not provided locally owned roads with a fair share of their users’ tax contributions. It's time to change that.

May 1, 2025

Trust Fund Babies: Advocates Argue House-Proposed EV Fee Won’t Solve Highway Funding Woes

An EV fee might make a dent in America's staggering transportation bills — but until the highway network stops growing out of control, it won't help for long.

May 1, 2025
See all posts