I-405 Widening Ready to Launch Outside Seattle

A major road-widening project will begin construction next year. The project is a long time coming for a fast-growing region, but the final product will reflect a new approach to highway funding.

1 minute read

September 11, 2018, 2:00 PM PDT

By James Brasuell @CasualBrasuell


Interstate Freeway System

Mark Payne / Shutterstock

Mike Lindblom reports on an impending highway widening project along 11 miles of Interstate 405 to the east of Seattle, connecting King County cities like Renton, Bellevue, and Woodinville.

The $1.2 billion project will use funding from a gas-tax increase implemented in 2003. "But if commuters hope to drive faster, they’ll need to pay again — because most of the new highway space will be express toll lanes," according to Lindblom. "The design adds one express toll lane and converts the free carpool lane to express tolls, alongside the existing two or three general lanes each way between Renton and Bellevue."

Lindblom also notes that several interchanges will be improved to alleviate logjams.

The new space on the highway will also be devoted to transit. "Sound Transit will create an 11-stop bus-rapid transit (BRT) network from Lynnwood to Burien, spending roughly $1 billion for passenger stations, highway ramps, buses and park-and-ride garages," according to Lindblom.

The article includes more details about the project, the expected impact of the changes on commuters in the region, and the politics of highway spending and tolling.

I-405 - Renton to Bellevue Widening and Express Toll Lanes (WSDOT)
"Planetizen federal action tracker" logo superimposed over black and white image of US Capitol dome.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

October 28, 2026 - Zachary Whalen

A car drives through a puddle, making a large splash. Rain pours down.

California plans to bury El Niño’s downpour

If the state plays its cards right, it may be able to store a billion acre-feet of El Niño’s water in aquifers.

October 28, 2026 - Grist

Lake Powell with much of the water evaporated.

Desperate measures: Advocates weigh draining Lake Powell to fill Colorado River

Draining the reservoir could reduce evaporation losses by a couple hundred thousand acre-feet.

October 30, 2026 - Yale Environment 360

: Construction of massive Samsung semiconductor fabrication plant

In Texas, data centers are swallowing promised parkland

Residents who moved to Taylor, Texas for a rural community now have to contend with three data centers in their backyard.

November 3 - Inside Climate News

A construction crew working on SunZia.

How a Chicago-sized wind farm beat the odds and powered on

The project spanned five presidential administrations and a standoff with a U.S. military base.

November 3 - Grist

A rendering of the basketball court, a green court under a blue sky.

MTA gives itself 30 days to transform pit into basketball court

The site has been under construction since 2022; the city originally estimated it would finish the court in 2024.

November 3 - Gothamist