BY ED FELIEN
Work began on the Franklin Avenue Bridge in April. This year construction will be limited to repairing the structural supports for the bridge.
Routine inspections found exposed steel rebar. Some of the concrete has worn through from repeated freezing and melting. According to HongPong, Dan Fiedt’s personal blog, “This effect is called spalling, where the concrete comes off the rebar. This pier has water seepage and refreezing splinters away from the concrete. The good news is that the structure under the deck looked OK—these piers have had serious waterfail though.” The bridge is structurally deficient, according to city documents, scoring a 47.6 out of 100 on a scale that measures structural soundness.
The steel rods or rebar are not simply placed loose in the concrete for additional support. The bridge is noteworthy for its use of Melan style reinforcing where trussed steel arches were embedded in the concrete.
In 1923, when it was built, it had the longest concrete arch in the world. The overall length of the bridge is 1,054.7 feet, and the central span is 400 feet.
The cement block pilings that supported the original steel truss bridge, built in 1889, can still be seen to the south of the current bridge.
Two years ago, Finance and Commerce said the estimates for the construction were $22 million. Today the estimates are $26 million, and the money will come from county, state and federal sources.
In addition to repairing and patching the support piers for the bridge, the project also will include a new deck, rebuilt railings, the installation of historically appropriate lighting, and a widening of the east side of the bridge by 10 feet. The county has also proposed that the renovation include a redesign of the bikeway on the bridge, allowing for a protected cycle track.
The structural repair of the piers will be done in the construction season of 2015. There may be temporary lane closures for pedestrians, bicyclists and automobiles while it is necessary to work on one side or another of the bridge, but the bridge will remain open in 2015. When the deck (the road surface of the bridge) is replaced in 2016, it is estimated that the bridge will remain closed from the spring to the fall of 2016.
Hennepin County says, “Bike lanes and sidewalk will be closed from 9 a.m. to 4 p.m. The eastbound bike lanes and sidewalks will be closed the first half of the week, and the westbound the latter half of the week. Pedestrians can cross the bridge on the sidewalk that is open. A signed detour will be provided. Bicyclists should use road lanes during this closure. Drivers should pay extra attention for redirected bicyclist and pedestrians in the area during this closure. “Share the Road” signs will be posted on the bridge. Vehicle traffic will be maintained in both directions during this work.”
