Dakota Creek bridge a 34.85 on sufficiency rating
The Dakota Creek bridge in Blaine
is one of two Whatcom County bridges classified as structurally
deficient by Washington State Department of Transportation,
department officials said this week.
The bridge, which spans 182 feet over Dakota Creek, earned a sufficiency rating of 34.85, out of 0-100 sufficiency rating scale, where 100 is a perfect score.
Harvey Coffman, an engineer with the DOT’s bridge preservation office, said the bridge’s low rating is primarily a result of aging and structural requirements at the time of construction.
“The limitations of this bridge are predominately limited to the timber spans on either end of the bridges, those timber spans have had some deterioration,” he said. “As a result, the structural adequacy is relatively low.”
Coffman, however, said that despite the bridge’s carrying capacity of 15 tons total weight, the bridge does not pose a safety threat to motorists.
He added that the classification “structural deficiency” is a bit of a misnomer, since the term is technically a rating tool used by the Federal Highway Administration FHWA to distribute funds to projects with the greatest priority.
“So in this context, when you hear of a bridge that is structurally deficient, there are a number of elements that are low enough from the data we collect,” he said. “A bridge has to have a sufficiency rating of 80 or less for rehabilitation funding, meaning to qualify for repairs. It must also have a rating of 50 or less to qualify for replacement funding.”
Coffman said the DOT requires engineers to inspect every bridge on the state system every 24 months. When crews spot advanced deterioration, they adjust the program to look at that particular bridge more often. The Dakota Creek bridge is currently subject to that increased monitoring program, he said.
The second bridge is the Mount Baker Highway bridge over Boulder Creek, near Deming. The 55-year-old bridge is subject to nearly annual flooding and is undergoing construction that began in June. The work, which will include widening and making the bridge taller, is scheduled to be completed in 2008, according to the DOT’s web site.
The Dakota Creek bridge was built in 1930 and rebuilt in 1951. It is scheduled for reconstruction during the 2007/2009 biennium, Coffman said.