Minnesota – The historic bridge carrying Franklin Avenue over the Mississippi River is getting a makeover in an innovative way meant to lessen construction time. “Pouring concrete on the bridge, according to Paul Backer, a county project engineer would have closed the bridge for two construction seasons.”
Instead, contractor Kraemer North America has been precasting 366 panels of the new concrete bridge deck just upstream at Bohemian Flats. From there, they’ll be barged to the bridge and hoisted to the deck by cranes. The cranes are also being used to lower 25-ton sections of the old 1970s bridge deck to barges below, to be ferried upriver and trucked to a crushing yard.
The 45 cross beams of reinforced concrete that support the deck will also be exchanged. The newly cast beams will feature scrolled ends that mimic the bridge’s original 1923 design. New side railings in the original design also will be installed, along with reproductions of the original ornamental streetlights.
Construction workers help guide a 12-foot-by-28-foot roadway panel down from the nearby Franklin Avenue Bridge after the concrete slab was sawed out of the bridge road on Tuesday.
The bridge, known officially as the Cappelen Memorial Bridge, joins others in the metro built with techniques that accelerate construction. The $51 million cost of the Franklin bridge project is comparable to what it would be under a more traditional approach, Backer said.
Innovative construction methods fit with the Franklin Avenue bridge’s history. It’s one of a series of bridges built by Minneapolis from 1914 to 1929 that attracted engineers from around the world. The five-span bridge stood out for its 400-foot central arch, the longest reinforced concrete arch in the world when it opened in 1923, something that later made barge traffic easier.
The current rehab aims to restore some grandeur while complying with modern standards such as safety and accessibility, said Kristen Zschomler of MnDOT, who worked with the county to comply with federal standards for historic properties. The bridge is a designated local landmark and on the National Register of Historic Places.
Construction workers help guide a 12-foot-by-28-foot roadway panel down from the nearby Franklin Avenue Bridge after the concrete slab was sawed out of the bridge roadway and removed via crane Tuesday.
A giant saw that can be remotely operated cuts through 12 plus-inch concrete roadway on the Franklin Avenue Bridge on Tuesday.
