By Ken Blake / The Data Reporter
Twenty-two Rutherford County bridges have deteriorated to the point of structural deficiency, according to the latest data from the Federal Highway Administration.
Plans are underway for repairing three of the bridges: one over Harts Branch on South Lowry Street in Smyrna, another over the Harpeth River on Highway 41A in the Eagleville area, and the Fate Sanders Bridge that carries Weakley Lane over the Stewart Creek area of Percy Priest Lake.
The remaining 19 bridges lie scattered throughout the county, some on little-used side streets but others on busy thoroughfares like Murfreesboro’s Church Street and Northwest Broad Street, where they handle more than 20,000 vehicles a day on average.
Rutherford County’s Structurally Deficient Bridges
Locations of the 22 Rutherford County bridges judged “structurally deficient” by inspectors, according to the 2015 National Bridge Inventory. Click or tap a marker to learn details about the bridge it represents. Red markers indicate spans with the worst ratings.
A structurally deficient bridge can look like it’s about to fall apart. For example, pedestrians crossing Smyrna’s Harts Branch bridge, the worst-rated bridge on the list, can scoop up handfuls of concrete chips that have fallen off the crumbling railings and balusters and spot rusting sections of rebar emerging from long gouges in the concrete near the deck. A look underneath the bridge reveals more rusty rebar visible through cracks that have opened in some of the beams or through holes left by fallen concrete chunks.
An Up-Close Look at the Harts Branch Bridge in Smyrna
Conditions on the Harts Branch bridge in Smyrna, Tennessee, can seem alarming. The damage looks worse than it really is, though, a state engineer says.
But the Harts Branch bridge looks more damaged than it truly is, Terry Leatherwood, a civil engineering manager in the Structures Division of the Tennessee Department of Transportation, said.
“When the concrete falls off, it looks real bad. But it’s nothing to panic about,” Leatherwood said, scrolling through the bridge’s November 2014 inspection report in his Nashville office.
Leatherwood explained that most of the bridge’s strength comes from reinforcement steel encased in the concrete. The bridge stands up by resisting both compression and tension forces, he said. The concrete counters compression forces. Primarily, though, the concrete protects the steel from the elements while the steel handles the tension forces, he said.
Cracks in the concrete pose a problem, he said, but chiefly because they let water reach the reinforcement steel. Water corrodes the steel, producing rust. When the steel rusts, it expands, producing more cracks that admit more water. “A vicious cycle develops,” he said.
Fellow engineering manager Brian Egli, who is overseeing plans to repair the bridge, said the bridge will get new railings, a new deck, and new beams. The department plans to release a bid in December detailing the work.
“It should last a good, long time,” Egli said of the bridge once crews complete the repairs. The work will consist mainly of setting precast components into place and shouldn’t require much time, he said.
Faron Todd, owner of Headliners, an auto upholstery shop he has operated for 20 years in a building beside the bridge, welcomed news about the bridge’s upcoming repairs.
“The bridge, as you look at it, nobody takes care of it,” Todd said. “The grass grows up … it just looks bad.”
A second bid, scheduled for release at the same time as the bid for the Harts Branch Bridge, will specify repairs needed to the Harpeth River bridge in Eagleville, according to Egli.
Meanwhile, the department already has released a bid for work on the Fate Sanders Bridge. Those repairs probably will begin this fall. Unlike the other two bridges, the Fate Sanders Bridge falls under the Rutherford County Highway Department’s jurisdiction, not the state’s. County Road Superintendent Greg Brooks said the Fate Sanders Bridge ranked as the worst of the bridges Rutherford County maintains.
Bridge “sufficiency ratings” explained
Each inspected bridge’s “Sufficiency Rating” indicates the bridge’s sufficiency to remain in service. Sufficiency rating scores range from zero to 100 percent, with zero percent indicating an entirely insufficient bridge, and a 100 percent indicating an entirely sufficient bridge. Additionally, each bridge’s deck, superstructure and substructure receive a rating on this scale:
8: Very good
1: Imminent failure
Any channels or culverts that carry water through the bridge are rated on a similar 0-9 scale, with ratings of 5 or lower indicating problems deemed “major” or worse.