West Seattle road-ramp breakdown is worse than just one hole

More is wrong with the loop ramp from the West Seattle Bridge to northbound Highway 99, than the sudden hole that opened up on the road deck May 2, leaving the busy road to close for six days.

This concrete curlicue, built in 1959, is riddled with smaller deck pits, and spots where chunks have separated from the edges, according to its most recent bridge inspection report, filed last August, which also described two other significant holes since 2020.

Nonetheless, the Washington State Department of Transportation classifies the deck condition as “satisfactory,” or a 6 on a scale of 0 to 9 in the National Bridge Inventory.

There’s been no timetable to rebuild the ramp, or even spend a few million dollars to replace the deck.

WSDOT is busy enough chasing road-maintenance jobs in places considered in even worse shape, or listed in poor condition and in need of immediate fixes, such as broken road panels between Snoqualmie Pass and Issaquah, or the recent deck repairs in Everett.

“For this bridge, the amount of patching and spalls has been under 1%, and that amount to us has been satisfactory,” based on standard criteria, said Roman Peralta, state bridge preservation engineer.

So the state will continue to patch and inspect the 64-year-old loop ramp over Sodo, even while Transportation Secretary Roger Millar emailed staff this month that “our system remains on a glide path to failure” because the Legislature’s 2023-25 budget invests too little in maintenance and preservation, compared to new projects.

The ramp suddenly failed, and damaged a few cars, when a broken deck piece created a hole the sun shone through. That’s after a similar hole opened in January 2022 that took two patching attempts to fill.

Nobody can predict if or where another hole will form somewhere within 18 deck spans of the 1,114-foot-long loop.

Peralta said the May 2 hole was reported to federal authorities as a critical safety event, and WSDOT will keep closer watch for deck deterioration.

“If the bridge is open, we deem it safe to travel on,” he said. The ramp carries 14,000 vehicles per day, and passengers on King County Metro bus routes C and H.

Marc Eberhard, a University of Washington civil engineering professor, said it’s fair to ask whether major deck upgrades are needed, given the age and the hole incident.

“The strategy one uses, depends on how it failed,” he said.

The National Bridge Inventory’s standardized ratings, derived from inspections of 8,333 Washington state bridges, can’t identify all potential weaknesses, he said.

WSDOT’s maintenance team traced this month’s hole to a failed patch, set 10 to 12 years ago, spokesperson James Poling said Friday. “We’ve viewed this as an isolated location.”

What inspectors know

Symptoms of the bridge’s old age appear in two inspection reports WSDOT provided to fulfill a Seattle Times public records request.

The August 2022 inspection said the surface is “heavily worn to aggregate,” so vehicles roll over exposed pebbles from the original concrete batch. Millions of tires have formed ruts a quarter-inch deep.

Inspectors logged 23 square feet of deck where surface material crumbled, sometimes exposing steel rebar. They’ve since been patched. That’s in addition to 103 square feet of previous patches.

Along the undersides of the decks and edge rails, they noted 25 locations of rusty rebar, cracks, spalls, or delamination where pieces peeled away. When exposed steel appears, crews typically scrape away loose concrete, then coat the rebar in rustproof epoxy, Peralta said.

A person standing below, in a Sodo steel company’s truck driveway, can view both patches, rusty gouges, and harmless white streaks.

It remains rated for 24 tons per axle, more than enough to support a 48,000-pound transit bus, though a passing concrete mixer truck Tuesday morning caused the ground to quiver.

One source of safety is the ramp’s dense shape. The deck sits upon center lengthwise beams, flanked by beams under each edge. A hole won’t spread across the entire deck, or trigger an entire segment collapse.

Workers made the most of this extra support in the May repairs, Peralta said. They cut the 5-by-4 foot hole out to 8½ by 7 feet, which allowed the patch of new concrete and existing rebar to adhere to the central beam.

How confident can WSDOT be that the loop ramp won’t spring another hole?

“I am confident that I will see a lot of deficiencies,” Peralta answered. “We see these every week. This bridge [hole] was considered a critical finding. It is on the radar. It’s something that will not go away. That is a second hole in two years.”

Bigger issues?

Will Knedlik, president of the Washington State Good Roads & Transportation Association, called failures like these “the chickens coming home to roost” after 25 years of shortchanging maintenance.

“It’s a compounding thing, and it’s a way for government to borrow without the public noticing until things start to collapse,” Knedlik said. He anticipates sudden breakdowns across the state.

For now, the loop ramp isn’t any to-do lists kept by WSDOT and the Legislature.

“Our ‘poor’ bridges are going to get priority over this one, and our present funding kind of limits that,” Poling said.

This spring, state contractors are refurbishing 17 areas in the Puget Sound region, and in 2024 will embark on a thorough and traffic-clogging rebuild of I-5 decks in North Seattle.

Preservation was touted as a cornerstone of last year’s $17 billion Move Ahead Washington package to boost long-term vehicle fees, driver service charges, and carbon taxes.

But lawmakers this year earmarked only $400 million for highway preservation in 2023-25, compared to Gov. Jay Inslee’s request for $810 million, online lists show.

“Postponing the work also poses safety hazards for travelers,” said a harsh letter by David Schumacher, Office of Financial Management director. Levels are so low the state would stop soliciting bids for major preservation projects, it said.

Washington state ranks better than most, with 423 out of 8,333 bridges, or 5%, labeled structurally deficient — 35th worst in the nation. By bridge surface area, 8% are deficient, or 12th worst, according to federal data. As for deck quality, WSDOT reports 93% of bridge surfaces in fair or good condition, meeting the state goal of 90%.

Besides its satisfactory ratings, the West Seattle-to-Sodo loop ramp wasn’t considered replaced or rebuilt during the Alaskan Way Viaduct replacement because the state’s project ended at South Holgate Street, a mile north.

Former Mayor Greg Nickels recalls there were talks in the 2000s about rebuilding Highway 99 all the way south to the West Seattle Bridge interchange, but the state balked at the cost.

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