There are more than 200 bridges in Washington that could collapse if a key part fails. They’re classified as being fracture-critical, just like the Interstate 5 span that plummeted into the Skagit River in May after it was hit by an oversized load. Out of those fracture-critical bridges, at least three others have been struck multiple times in the past five years. Experts say repeated bridge strikes can potentially cause catastrophic problems.
The three fracture-critical bridges in the state that have been hit more than once are a US Highway 101 bridge, a state Route 4 bridge over the Elochoman River, and the Kummer Bridge along state Route 169.
The US Highway 101 bridge carries Simpson Avenue over the Hoquiam River. It’s been hit six times since 2007 according to state data.
The state Route 4 bridge was hit in 2008 and 2011 and the Kummer Bridge was hit twice in 2008, most likely by work crews who were making repairs.
Aside from the three fracture-critical bridges that have documented hits, a review of state data shows that six other bridges have been hit five times or more between 2007 and 2012. Those other bridges, however, are not designated as fracture-critical.
Repeated bridge strikes are a concern for federal safety inspectors investigating the collapse of the Interstate 5 bridge in Skagit County. That bridge also apparently suffered multiple hits, though no one knows exactly how often. “Some of them may or may not have been reported,” said NTSB Chair Debbie Hersman. “We have got to pull together a lot of different records, both from WSDOT and the state patrol to identify a comprehensive list.”
State officials record bridge strikes during regular inspections or when a collision is reported. But if no one witnesses a bridge strike, or if the crash isn’t reported, the impact may not be known until an inspection. The state does not have a comprehensive way to record every bridge hit.
Experts say repeated bridge strikes can be disastrous. Jeffrey Berman, associate professor at the University of Washington’s Department of Civil Engineering, said problems can occur if the strikes repeatedly hit the same place on a bridge. “You could start to damage its connections; you could really then have an impact.”
Still, Berman also said that it’s highly unlikely that a truck can hit a bridge in just the right way to cause a collapse. He said the bigger threats to bridges are earthquakes, corrosion and inaction by policymakers. “We do have an infrastructure problem in the US. It’s a maintenance and repair issue. The fact is that in cities like Seattle, the population has grown and the infrastructure has not,” said Berman.
The notion of expanding the state’s infrastructure is not getting much help from state lawmakers. This past session, the state Senate balked at legislation that included money for new highways, bridges and new support for transit. Berman said that decision saddened him and says more should be done for infrastructure.
“We definitely see its importance when it fails,” he said. “But we often fail to realize its importance when we’re using it and it’s operating well.”