In January, if West Seattle commuters caught in a bottleneck had gazed out the window at their high bridge and wondered about its safety, a look at federal bridge ratings may have calmed their nerves. The bridge was labeled sufficient. In a catchall rating out of 100, it had a respectable 69.
By the spring, the city had discovered that cracks in the bridge were accelerating, closed it with no definite reopening date and begun preparing emergency plans in the event — which the city says is unlikely — the bridge collapses.
The abrupt turnaround for the West Seattle Bridge, which carried 125,000 travelers a day, underscores how even structures deemed sufficient by federal authorities can face serious problems and create new transportation crises. And in Seattle, dozens of other bridges have lower overall ratings than the now-closed span, some with key vulnerabilities the West Seattle Bridge never had.
Meanwhile, city spending on bridge maintenance and replacement is far below what is needed, according to the Seattle Department of Transportation’s own experts. Bridges here and across the country are aging beyond their expected lifetime as public budgets face a new pressure: the coronavirus pandemic.
Seattle is in the process of auditing the condition of its 124 bridges and spending on maintenance, after a request from Seattle City Councilmember Alex Pedersen.
A look at local and federal reports offers a sense of what the city will find.
Among the Seattle bridges with lower ratings than the West Seattle Bridge, six have a label never attached to that span: They are deemed structurally deficient or rated “poor,” meaning they need significant repair or replacement. Nine bridges have structures that are fracture critical, meaning they could fall if a certain major part is damaged, as happened in the 2013 Skagit River bridge collapse.
Experts warn that no one of these measures is a perfect indicator of a bridge’s safety, and they emphasize that any sign of risk to the traveling public is likely to get a bridge shut down, regardless of its rating. The National Bridge Inventory, where these ratings are kept, can give a picture of which bridges may need replacement or repair in coming years.
Some low-ranked Seattle bridges, like the decaying Fairview Avenue North bridge, with its 25.8 grade, are getting city attention and replacement. For others — like the 91-year-old Magnolia Bridge and the fracture-critical Ballard Bridge — the city does not yet have funding or firm plans for replacement.
SDOT’s list of structurally deficient bridges includes the Magnolia Bridge, two portions of the Fairview Avenue Bridge, a bridge at West Dravus Street over 15th Avenue West, and bridges in Pioneer Square on South Main Street and the 2nd Avenue extension.
In federal ratings, the 90-year-old University Bridge, which carries 36,000 trips a day, is also listed as being in poor condition with a low rating for its substructure, the part of a bridge that includes supporting elements like piers and foundations.
A lack of funding for bridge repair has long been a concern for the city’s bridge experts, annual reports from the Seattle Department of Transportation (SDOT) since 2014 show. Seattle’s bridge maintenance budget remained roughly steady from 2012 to 2015 and got a bump in 2016 after voters passed the Move Seattle levy.
In recent years, SDOT’s budget for bridge maintenance has been about $7 million a year, according to the city, far short of the roughly $68.5 million SDOT says it should be spending each year.
In a statement, SDOT said Seattle, “like every major city in the United States,” has seen “grossly insufficient funding support from the federal government.” SDOT cited state taxation issues and the federal gas tax, which hasn’t increased since 1993, for the lack of money.
“Despite these challenges, the Seattle Department of Transportation continues to prioritize the safety and resiliency of our transportation infrastructure,” the statement said. The agency did not make anyone available for an interview.
Even if the city spent $100 million a year toward replacing bridges, a 2018 SDOT report noted, it would take 30 years to replace all the bridges that are over 60 years old. Including maintenance, replacements like the Fairview Avenue Bridge and other work, SDOT’s total annual bridge spending has been between $40 million and $75 million in recent years.
The rate of deterioration and the age of Seattle’s bridges and other structures, the report said, “are making our current funding practices inefficient and unsustainable.”
Statewide, funding for maintenance and preservation is about half of what’s needed, said Mark Gaines, bridge and structures engineer at the Washington State Department of Transportation (WSDOT). “That puts us in the difficult position of what to prioritize and what to defer,” he said.
The 2013 collapse of an Interstate 5 bridge over the Skagit River drew attention to the state of the state’s bridges. Though the Skagit Bridge was structurally sound, the bridge was fracture-critical and one section was ruined by a tall load that hit an overhead brace.
After the collapse, WSDOT said 143 state-maintained bridges were classified as structurally deficient. In 2020, WSDOT listed 155 bridges as rated “poor,” a new rating term for bridges previously described as structurally deficient.
The label of structurally deficient or “poor” means bridges have at least one component in poor condition that’s likely to eventually need repair or replacement. Fracture-critical bridges can trigger extra inspections, Gaines said.
The federal sufficiency rating — the score out of 100 — is a combined analysis of the structures of the bridge, the condition of the deck, its average daily traffic and other factors, and is mostly used for trying to get federal funding, Gaines said. A low rating, combined with factors like how important a bridge is to the movement of freight, can help prioritize it for funding.
None of these is a perfect measure of a bridge’s safety.
“The idea of safe as an absolute black and white is deceptive,” said University of Washington civil engineering professor John Stanton, “because everything is really a scale of gray and the question of where on that scale you’re willing to live.”
Engineers can learn new information about certain types of bridges after they’re built, like the level of concrete creep on the West Seattle Bridge or the seismic vulnerability of the hollow columns in some bridges the state has worried about in recent years.
Washington ranks around the middle of the pack compared with other states for its share of structurally deficient bridges by deck area. Although the state has one of the highest gas taxes in the country, much of that money is dedicated to pay off bonds on existing projects rather than fund new projects or maintenance.
King County, too, has struggled to adequately fund bridge replacement and repair in unincorporated areas. Of 182 bridges in those areas, 75 are beyond their expected useful life, according to a 2018 county report.
Seattle and Washington have unique risks.
Because of geography, a major corridor shutdown in Seattle can tangle traffic due to few alternative routes.
Another risk: the Big One. Researchers, who in recent years discovered that ground motion from a major quake will be even riskier for tall buildings than previously known, are turning their attention to state bridges.
This January, work began to study the types of state-owned bridges that could be most vulnerable to a magnitude-9 earthquake, said UW civil engineering professor Marc Eberhard.
Nationally, the share of bridges that are structurally deficient has fallen, but progress has slowed in recent years, said Andy Herrmann, a retired bridge engineer and past president of the American Society of Civil Engineers.
That could indicate governments have addressed much of the lowest-hanging fruit, leaving the harder and more expensive work still to be done. Bridges will continue to age, adding to the to-do list.
“We’ve let them ride for quite some time,” Herrmann said.