Austin bridges classified as substandard

Published 7:27 am Friday, July 23, 2010

Three Austin area bridges are included in the list of the state’s 25 percent of bridges identified as functionally obsolete and structurally deficient this week by the Federal Highway Administration (FHA).

The bridges located on County Road 46 and Highway 218, which both run over Interstate 90, have been deemed functionally obsolete — a classification based primarily on the inadequate width size of each structure. Turtle Creek Bridge, which also runs over I-90, was classified as structurally deficient and is currently in the process of being replaced.

While classifications may sound daunting to motorists, Jessica Wiens, public affairs coordinator for Minnesota Department of Transportation (MnDOT) district six, said bridges included in the report pose no immediate threats.

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“It’s not a factor of if a bridge is going to collapse or not going to collapse,” Wiens said. “It’s a factor of whether it needs repairs or warrants replacement.”

Each bridge in the state — and country — is rated on a scale of zero to 100, with a zero rating indicating that a bridge is entirely insufficient. Every year, the FHA compiles ratings from around the country into an annual report.

The scale is used primarily to determine the bridges that qualify for federal repair or rehabilitation funds, according to Wiens. If a bridge receives a rating of 50 or below, it could be subject to federal replacement funds. If a bridge’s score falls below 80, federal rehabilitation funds may be allocated for the repair of the bridge.

In the Austin area, two of the three bridges included in the report qualify for federal funds: the Turtle Creek Bridge received a rating of 65.7, while the Highway 218 bridge over I-90 received a 71.1. The County Road 46 bridge earned a score of 89.9.

Bridges are determined to be structurally deficient or functionally obsolete based on problems identified with each structure — point systems have nothing to do with such classifications.

A bridge is generally classified as structurally deficient if portions of the structure are considered to be in poor condition. Craig Falkum, MnDOT district six structures engineer, said when it comes to evaluating a bridge, it’s kind of like dealing with an old home.

“Bridges are like your house,” he said. “A new house is great, but after 20 or 30 years, it starts to deteriorate.”

That doesn’t mean a bridge is on the verge of destruction — it just means it needs some updates, he said.

In order to determine if the structurally deficient bridge is in need of repair, its deck — or base — and structural components, including beams and handles, are evaluated. Every structurally deficient bridge is given a rating on a scale of zero to nine. If a bridge is rated at four or less, it is considered to be in poor, serious or critical condition. In the case of the Turtle Creek Bridge, Falkum said problems were identified with the concrete girders, which moved the bridge into a category that qualified it for repair.

The additional two bridges in Mower County considered to be functionally obsolete recently underwent repairs as well, Falkum said.

Earlier in the summer, MnDOT replaced the deck — or base — of the County Road 46 bridge. The Highway 218 bridge received the same update a couple years ago.

Falkum said each bridge is in good condition and were likely deemed functionally obsolete because of their narrow designs — each bridge has less than a 12-foot lane. In order for MnDOT to consider widening a bridge, it has to have good reason. A number of components are considered, including the amount of traffic a bridge sees, the number of cyclists and pedestrians that regularly cross and the type of vehicles that generally travel over the structure.

“The width was not a big factor to warrant rehabilitation or replacement of the bridge, so we did a major replacement on it,” Falkum said of the two Austin bridges.

Falkum said the two bridges will not likely be the subject of major renovations or replacements in the near future.