MnDOT hopes Stone Arch Bridge repair money coming soon

The Stone Arch Bridge in Minneapolis — last repaired in the mid-1990s — could eventually shut down if the Legislature fails to allocate $13 million for rehabilitation, a Minnesota Department of Transportation official said Thursday.

The popular and picturesque 135-year-old pedestrian bridge over the Mississippi River in downtown Minneapolis is overdue for major work and needs all new mortar as well as some new stone, said Amber Blanchard, MnDOT's state bridge planning and hydraulics engineer. MnDOT hopes to start construction on the St. Anthony Falls landmark as early as 2020.

"If we don't get the money ... it could deteriorate to the point where we would have to close it," Blanchard said. "It is really due for a major fix."

Gov. Mark Dayton has included nearly $13 million for inspection, design and construction of the bridge in his 2018 capital budget proposal.

Rep. Dean Urdahl, R-Grove City, chairman of the House Capital Investment Committee, said he hasn't seen a bill specifically asking to allocate money to the bridge.

"We are still going through the process, vetting projects and hearing projects," Urdahl said. "We'll take a look at it. Bridges are one thing we are looking at. ... I'm not going to assign ratings at this time."

For the bridge to be deemed unsafe for public use, inspectors would need to identify a major issue like a problem with its steel spans or a crack in a beam, Blanchard said. She said she isn't sure exactly when the bridge might become unsafe without upgrades.

Minneapolis Public Works Director Robin Hutcheson said she hopes residents never have to find out.

"I think through routine and more substantial maintenance, such as what's being proposed here, we will avoid any [potential] shutdown," she said.

Third Ward Council Member Steve Fletcher said he pushed the city to include full support of MnDOT's Stone Arch Bridge request in its 2018 legislative agenda.

"I think of the bridge, really, as one of the social and logistical connections between the people in my ward," he said. "I am pretty convinced that we're going to find money for it. ... We should be investing to expand that area, rather than let it decline."

If the state allocates the money, construction could start as early as 2020, Blanchard said. Public access to the bridge could be limited for short periods of time during construction, she said.

A 2017 inspection revealed that all the bridge's mortar needs to be replaced. Mortar repointing is a "big undertaking" that requires chipping away 4 to 5 inches of deteriorated mortar and replacing it with new material, Blanchard said.

The process is easier in dry conditions, so workers will likely have to set up barriers around the bridge's bases to block the river's flow — an expensive endeavor, according to Blanchard.

Plus, officials estimate that at least 20 percent of the stone masonry must be replaced, based on the 2017 inspection. Blanchard said this requires consultation with historians to ensure the new stone fits the structure's history.

MnDOT has requested several million dollars for Stone Arch Bridge repairs each year since 2015 but has not received state money, she said. In its 2015 request, the department warned that "without repairs, the bridge will continue to deteriorate, resulting in more repairs at a higher cost in the future."

The bridge, built from 1881 to 1883, was constructed by Minnesota railroad baron James J. Hill and functioned as a railroad bridge through the 20th century. It was converted to a pedestrian crossing in the mid-1990s.

Rilyn Eischens is a University of Minnesota student on assignment for the Star Tribune. Staff writer Karen Zamora contributed to this report.