Seattle-area traffic will take a hit with Ship Canal Bridge repaving

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Two lanes of the I-5 Ship Canal Bridge will close for four weeks beginning the night of July 25 so contractors can begin to repave its worn-out concrete deck, a project sure to worsen traffic congestion.

In a change of strategy, the Washington State Department of Transportation announced Tuesday it would repave the road on 20% of the bridge length, instead of punting the whole project until next year, as WSDOT Secretary Julie Meredith had envisioned in January.

This summer’s 900-foot redecking, along two interior lanes just beyond Roanoke Street, will expose any nasty surprises beneath, such as trapped water or rebar corrosion that could make replacing all eight lanes an ordeal in 2026-27.

Resurfacing must be aimed at dry times of year so workers can apply the synthetic concrete. The state’s August timeline allows some leeway to stretch into September if crews were to discover severe damage. Ordinarily, the job should require scraping and repaving 1½ inches deep, but builders may need to punch out and rebuild all 6½ inches of deck anywhere it’s flaking apart.

WSDOT hopes the contractor, Atkinson Construction, will learn from the four-week partial repaving, enabling speedier progress later, while reducing the risk that the complete I-5 bridge upgrade drags past 2027.

“In the end we will have a safe, reliable bridge for years to come,” said a statement by Brian Nielsen, regional administrator.

Experience on this starter segment could make for more accurate cost estimates as the state and Atkinson renegotiate their $203 million contract, said Travis Phelps, WSDOT’s management of mobility director.

Many of the quarter-million daily car trips on I-5 will be canceled, detoured or delayed during summer work. The work zone will extend nearly a mile, before and after the 900-foot paving area, to allow room for cars merging and for contractors’ machinery. The speed limit will be 50 mph.

However, WSDOT will keep the express lanes pointing north all day, to compensate for crews occupying half the northbound mainline. That will cause morning delays southbound.

There will also be full weekend closures of the northbound mainline, from I-90 to the University District, during the July 26-27 and August 23-24 weekends, so concrete work-zone barriers can be set and removed.

Future phases are still being renegotiated, Phelps said. WSDOT remains committed to avoiding freeway lane closures during the FIFA World Cup, when Seattle hosts six international soccer matches in June and July 2026.

The bridge, which opened to traffic in 1962, last underwent major resurfacing in 1985, and is considered safe. However, anytime pavement crumbles on a highway bridge, the odds increase that runoff will eventually weaken steel rebar or girders.

Two parks beneath are closed because pieces of concrete occasionally fall. The parks will remain closed until the deck is fully repaired.

Money and traffic

WSDOT’s new strategy helps solve a cash-flow problem Meredith cited in January when canceling the scheduled spring redecking of a longer 4,400-foot-long, two-lane section. That full distance required $86 million, or $16 million above past estimates, with a risk of being even pricier, she said — while this year’s highway preservation funds were running low. To fix only 900 feet this year avoids depleting near-term budgets.

Washington devotes about $1 billion of its $15 billion biennial transportation budget to “preservation,” such as major deck repairs, seismic improvements, bridge-beam painting and asphalt pavement statewide. The I-5 Ship Canal Bridge, a regional and national example of aging highways, has needed more than 200 urgent pothole repairs since 2019.

Kris Abrudan, WSDOT strategy and policy director, said recent proposals to raise the gasoline tax by at least 6 cents per gallon are unrelated to the July roadwork, which can proceed regardless of whether a bipartisan tax bill for transportation passes in the 2025 legislative session ending April 27.

Meanwhile, a separate request to the Legislature by Seattle Mayor Bruce Harrell, the Downtown Seattle Association and King County Metro Transit for $39 million in extra bus service, traffic signals and trip-reduction programs to offset I-5 congestion through 2027 is still unresolved. Regardless of those results, Abrudan says this summer’s 900-foot repaving will proceed and “we’ll do an extensive amount of outreach for this work.”