You might call it the “perfect storm” of bridge repair. Come next year, three historic bridges – the 10th Avenue Bridge, the 3rd Avenue Bridge and the Stone Arch Bridge – are slated for repair jobs that will keep the first two, at least, shut down for a year or more.
Third Ward Council Member Steve Fletcher, State Sen. Kari Dziedzic and State Rep. Diane Loeffler were all on hand at a Jan. 14 meeting at DeLaSalle High School where engineers from the City of Minneapolis and the Minnesota Department of Transportation (MnDOT) laid out plans for repairing and restoring the bridges. All three projects have funding, and the two entities are working on a coordinated plan to keep traffic disruptions at a minimum.
10th Avenue Bridge
City engineer Don Elwood said “the 10” project is a rehabilitation, not reconstruction. Opened in 1929, its decorative railings were replaced in the 1950s, its deck was replaced in the 1970s and it was placed on the National Register of Historic Places in 1989. It is considered a fine example of a reinforced concrete bridge from the early days of automobile usage.
The upcoming project, slated to begin this fall, will require replacement of the bridge deck, which has been compromised by water infiltration between the joints and rusted-out rebar. The repair ticket also includes repairing floor beams, columns, arches and piers.
Also included in the project is the removal of a water main from under the bridge. The main, which carries fresh drinking water from the Minneapolis water treatment plant, will be tunneled under the river. Re-routing the big pipe will take place this summer.
When the bridge work is completed in 2021, traffic lanes on the city-owned bridge will be different. Currently, the 10th Avenue Bridge has two lanes running each way for bus and car traffic, a bike lane and a 10-ft. sidewalk. In its new configuration, it will have one car lane going each way, a two-way bike lane with a raised concrete barrier, and a 12-ft. pedestrian walkway.
3rd Avenue Bridge
The State of Minnesota owns the 3rd Avenue Bridge, so MnDOT has responsibility for its upkeep. The Third Avenue Bridge is the longest S-curve shaped concrete arch bridge in the world. It was designed that way to take advantage of a more stable limestone formation in the river bed and to provide views of St. Anthony Falls.
The 100-year-old bridge (it opened in 1918) underwent its first rehab in 1939, when streetcars ran across it. Its second rehabilitation took place in 1979-80 when its deck, approaches and abutments were replaced. It was repaired again in 2003, when the deck’s expansion joints were replaced. Work was done on the piers in 2014. A protected bikeway was added in 2015. Chris Hoberg, MnDOT project manager, said water intrusion on the bridge deck was the primary cause of the bridge’s deterioration.
The scope of the project includes top-to-bottom work, replacing the deck, some of the spandrel columns that support it, repairing the arches and surface repairs to the piers that anchor the bridge to the river bed. Retaining walls next to the bridge will also be rebuilt.
Hoberg said MnDOT has a number of restrictions placed on what it can do to the bridge because it, too, is on the National Register of Historic Places. “We cannot widen the bridge,” he said. “Under the rules set out by the Secretary of the Interior, we cannot change its character, its ornamental Art Deco railing, its curvature or its arches.” MnDOT will rebuild an existing staircase at the bottom of the bridge, but cannot bring back the spiral staircase it had when it first opened.
MnDOT also has to take into account a high-transmission power line that looms over the bridge, archeology, sensitive historic buildings and how to provide a safety railing (the current one is not crash-tested).
The project is expected to begin in late 2020 and take up to 30 months to complete, giving it an early 2023 opening. Bicycle and pedestrian access to the bridge will be closed and car and bus traffic will be re-routed. Main Street will most likely close for one or two days when the deck is removed.
Stone Arch Bridge
Amber Blanchard had good news to deliver to the people who packed the meeting room at DeLaSalle: Funding for repair of the Stone Arch Bridge had been secured from the Legislature that very day. The newly-named project manager for the Stone Arch project said the project is expected to cost $15 million. The Legislature approved a $1 million appropriation; the rest will come federal and Minnesota Rail Service Improvement Funds. Said Sen. Dziedzic, “[MnDOT Commissioner] Margaret Anderson Kelliher looked under all the couch cushions to find this money.”
The 2,100-ft.-long bridge was built in 1883 out of limestone blocks set on granite piers at the waterline. A railroad bridge for most of its life, it became a bike and pedestrian bridge in 1993.
Blanchard showed several photos of areas on the bridge that need repair. Blocks on the underside of the arches are cracking, caused by the freeze/thaw action of Minnesota’s winters. Concrete around the pier bases is delaminating. Several blocks no longer have mortar between them. In the 1960s, the railroad installed tie anchors into the bridge to keep the tracks in place. Those anchors are rusting out.
Some of the limestone blocks were replaced in the 1960s with concrete blocks; Blanchard said they would remain because they are “part of the bridge’s historic fabric.”
Blanchard said she doesn’t yet have a start date for the bridge’s rehabilitation, but her goal is to begin late in 2020 or early 2021. She also said she doesn’t yet know if the bridge will be closed while the work proceeds. “I’m going to try to keep it open,” she said.
Below: Work on the 10th Avenue Bridge, shown far left, is more of a rehabilitation than a reconstruction. (Photo provided by MnDOT) A lot of work needs to be done from top to bottom on the 3rd Avenue Bridge, shown left. (Photo by Nik Linde) Funding has been secured to repair the deteriorating Stone Arch Bridge. Work on it will hopefully begin in 2020. (Photo by Nik Linde)