Pullman and Moscow contain “functionally obsolete” bridges similar in rating to the recently collapsed Interstate 5 Highway bridge in Mount Vernon, Wash., according to the National Bridge Inventory Database.
A section of the I-5 Highway bridge collapsed into the Skagit River May 23, dropping cars with passengers into the water. The National Bridge Inventory Database had listed the Skagit River bridge as functionally obsolete. These bridges may have substandard lane widths, narrow shoulders or low clearance for large trucks, according to the Washington State Department of Transportation website.
Sufficiency ratings determine which bridges need repair or replacement, but do not specify a bridge’s ability to carry traffic. The ratings are based on a 0-100 scale, with zero being the worst and 100 being the best. A bridge’s sufficiency rating is important for accessing federal funding for maintenance, rehabilitation or replacement, according to the Department of Transportation website.
The Kamiaken Street bridge in Pullman has a rating of 72.4 percent and is structurally deficient.
Kevin Gardes, the Pullman Public Works Director, said the city had plans to repair Pullman bridges before the collapse occurred in Skagit County. The city plans to lay an inch and a half layer of concrete on the Kamiaken Street Bridge later this year or in early 2014, he said.
Gardes said Public Works received a $285,000 grant from the Department of Transportation to improve the street bridge.
“Our bridges are generally built well,” Gardes said. “We address any deficiencies in the bridges and we have qualified bridge inspectors to identify mistakes.”
Ten bridges in Whitman County are also listed as structurally deficient, according to the National Bridge Inventory Database. However, the definition of structurally deficient bridges does not suggest that the bridges are in danger of collapsing or unsafe to travel across.
In Latah County, Idaho, five bridges are labeled as functionally obsolete and eight bridges are structurally deficient. Two of the five functionally obsolete bridges in Latah County are in Moscow. However, both bridges hold high sufficiency ratings.
Les MacDonald, the Moscow public works director, said the Skagit River Bridge collapse will not present significant changes to their bridge inspections.
“Each structure has limitations,” MacDonald said. “Bridges are a part of our system and we inspect them every two years.”
MacDonald said the city maintains nine to 10 bridges, and the current structures sit in good condition. He said the lack of funding poses problems for many states trying to repair damaged bridges.
To increase safety, it is critical to repair structurally deficient bridges, MacDonald said.
Sufficiency ratings vary depending on the type of structure and inspections performed on the bridge's foundations, streets and sidewalks, he said.
“Sufficiency ratings look at the different components in a structure,” MacDonald said. “We inspect all of these materials and the rankings added up give the bridge a rating.”
A bridge which is determined to be functionally obsolete, like the Skagit bridge, affects traffic flow, he said.
Washington state contains nearly 7,000 bridges on state, city and county road systems, according to the Department of Transportation website.