Drivers on the Aurora Bridge could lose a traffic lane for several more days until the Washington State Department of Transportation can repair “advanced deterioration of steel” within the 90-year-old span’s arch structure.

That means possible traffic delays, in addition to routine congestion for one to two miles entering downtown Seattle on weekday mornings.

The far-right lane remained blocked Monday after inspectors last weekend located rust damage below decks, near the middle of the span. WSDOT spokesman Bart Treece said the problem appears in a lengthwise beam called a stringer that runs between major crossbeams and supports the deck.

“We’re keeping that lane closed to reduce any additional stress on the bridge until repairs can be completed,” Treece said. Further details from WSDOT’s bridge team are expected Monday afternoon.

The Aurora Bridge was dedicated in 1932 and underwent a significant seismic retrofit, completed in 2012, after the 2001 magnitude 6.9 Nisqually earthquake. It was recently repaved and repainted.

During a routine inspection in September, bridge staff located some “pack rust,” Treece said. They decided to make a deeper, follow-up inspection that occurred last weekend. Pack rust refers to rust that accumulates between steel plates and can bend small areas.

Advertising

“The bridge for the most part is in pretty good shape,” Treece said. Routine inspections were performed in 2015, 2017 and 2019, he said.

Asked why the state didn’t find and fix the rusted beam sooner, Treece said “we moved as quickly as we could” to do the second inspection, and then close the outer lane as a precaution.

Traffic moved at close to normal speeds Monday morning as drivers merged into just two inbound lanes. Once cars and buses pass the weak spot, the bridge reopens to three southbound lanes, and traffic between 7:30 a.m. and 8:30 a.m. moved at 30 mph or quicker after passing the blockage.

King County Metro Transit said its buses, including the RapidRide E Line, experienced delays of four minutes at 7:30 a.m. and eight minutes by 8 a.m.

Bus drivers often straddle two lanes anyway, and some car drivers shun the center lane that has no median barrier — so that even on a normal day the span doesn’t fully function as a six-lane bridge. The lanes are only 9 to 9 1/2 feet wide.

A few years ago, the city studied four- and five-lane configurations for the bridge but suspended that effort following a 2015 crash involving a Ride the Ducks vehicle and a charter bus that killed five people and spawned lawsuits and financial worries for the city.

The Aurora Bridge carries 62,000 vehicles per day, Seattle’s fourth-busiest arterial after the high West Seattle Bridge, East Marginal Way South, and the Montlake Bridge.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com.