Franklin Avenue bridge over Mississippi unsightly, but safe

The Franklin Avenue bridge spanning West River Parkway and the Mississippi River is practically new, and already blemishes are appearing.

Concrete has flaked off the top of the railing at places along the 1,054-foot bridge that was rehabilitated during the 2015 and 2016 construction seasons. Cracks have appeared at a few of the pilasters, those sections of the railing that appear to support a column but really are more ornamental than functional.

"If you look at many sidewalks and driveways, you see that kind of surface defect not long after the pour," Drive reader Bruce said in an e-mail that was accompanied by photos highlighting the imperfections.

"If it were limited to one area, I would not be upset; that would indicate the concrete was not handled right during construction. But it is happening in many places on the bridge."

There is no cause for concern, said Bob Beckel, the Upper Midwest regional manager for Kraemer North America, the contractor hired by Hennepin County to carry out the $51 million bridge reconstruction. The flaws may be unsightly, but "there is no structural issue," he said.

Officially known as the Cappelen Memorial Bridge, the project was a complex process. More than 366 precast panels were built upstream at Bohemian Flats, then loaded onto a barge and floated downstream. At the bridge site, the pieces were hoisted by cranes into their final positions. The bridge got a new deck and new features that included protected bike lanes, sidewalks and overlook areas.

Colin Cox, a spokesman with the Hennepin County Transportation Department, said the county is working with Kraemer to determine exactly what caused the defects. He said the bridge is still under warranty and problems will be repaired.

Beckel said there may have been too much clay material mixed in with the concrete, and that might explain the flaking on the railing. When the material expands, it causes pop-outs. It's a common problem that can easily be fixed, he said.

Blight near the pilaster bases could have resulted from salt interacting with the concrete and taking the coating off — another common occurrence on bridges, Beckel said.

The larger cracks that have formed in the bottom corners of a handful of pilasters "are disappointing," Beckel said. At 10 places along the bridge, pilasters were poured near an expansion joint. When the joints expanded in hot weather, the rail moved slightly and pulled away from the precast pilaster.

"It's an expansion-contraction issue that can be taken care of pretty easy," Beckel said. "It's nothing to be alarmed about."

One eastbound lane on the new Franklin Avenue bridge spanning Interstate 35W is expected to open to traffic Monday. A westbound lane opened earlier this month. All lanes on the bridge should be open by mid-July, said MnDOT spokesman David Aeikens.

Plans for rebuilding Hennepin Avenue will be presented from noon to 5 p.m. Thursday at the Hennepin Theatre Trust, 900 Hennepin Av. See the ideas for the road layout and visions for streetscape enhancements. The $20 million makeover from Washington Avenue to 12th Street is likely to run from 2019 to 2022.

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612-673-7768.