Badly corroding Minneapolis Northtown bridge nears replacement

  • Article by: STEVE BRANDT , Star Tribune
  • Updated: April 1, 2013 - 10:32 PM

Minneapolis bridge has spanned the years from steam to diesel, but it’s off limits to heavier vehicles.

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The Northtown Bridge has the lowest structural fitness rating of any bridge in Hennepin County and needs to be replaced. The question is: with what?

Photo: Jerry Holt, Star Tribune

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It took decades of debate to decide that it’s more cost-effective to replace than fix a risky Minneapolis bridge, but before the new span is built there’s still more discussion ahead on what it should look like.

The Northtown Bridge in northeast Minneapolis is the city’s worst. Metro Transit buses can’t use it, and there are weight limits for trucks.

The bridge is deemed structurally deficient and fracture critical, meaning a whole span could fall if a single key support failed. It’s in such rough shape that it rates 2 out of 100 on a structural fitness scale used by bridge inspectors, the lowest in Hennepin County.

“It’s in bad shape, and it’s been a point of concern for a long time,” city bridge safety inspector John Beetsch said.

The bridge carries St. Anthony Parkway over the Burlington Northern Santa Fe rail yard. Construction isn’t likely to start until at least late next year on the badly corroded truss bridge that carries about 4,200 vehicles on an average day. That’s despite years of load limits to protect the five-span bridge until a replacement comes;

A lengthy debate

Efforts to improve the crossing date back to the late 1980s, according to the city’s Public Works Department.

But while $28 million was being stockpiled, it took years to decide whether it was more cost-effective to repair or replace the 88-year-old bridge, which spans 533 feet over about 20 tracks. That happened as cost-benefit criteria shifted and preservation authorities were opposing a replacement.

“The more analysis we did, the more expensive we found the bridgework to be,” said Jack Yuzna, a city bridge engineer. Rehabbing the bridge would have been complicated because it crosses working rail lines, making the work more difficult than if the bridge spanned a river or a ravine, Yuzna said. Eventually the city concluded it would need to move the five bridge trusses off-site in order to work on them, given the roughly 100 trains per day that pass below in what is BNSF’s main rail yard in the state.

A state historic preservation review urged that the current bridge be kept. “Our office felt very strongly that it could be repaired rather than demolished,” said Mary Ann Heidemann, who manages compliance for the Minnesota Historical Society. The bridge is one of a dwindling number of Warren through truss bridges in the state, so called because traffic drove between twin ranks of trusses. “It’s been a very protracted process,” she said.

Citizens weighing in

The Federal Highway Administration ruled for replacement, and now there’s debate over the type. Yuzna said the city is proposing a 320-foot tied-arch main span flanked by two shorter girder bridges. Some community residents favored a taller cable-stay bridge, the style used in the <URL destination="http://en.wikipedia.org/wiki/Martin_Olav_Sabo_Bridge">Martin O. Sabo<PARAGRAPH style="$ID/[No paragraph style]">cq

The area is sensitive to preservationists because the current Northtown bridge is deemed eligible for the National Register of Historic Places, and it’s on the register-eligible Grand Rounds of parkways and crosses the register-eligible rail yard. Hennepin County’s new Lowry Bridge is a basket-handle tied-arch bridge but Yuzna said a Northtown tied-arch bridge likely will lack the distinctive basket handle of the Lowry span.

That’s fine with one older bridge neighbor, Ted Szymanski, who labels the colored lights of the Lowry span ”psychedelic” and its design out of place. (Those lights turn pastel this week for Easter and then blue and white for the Twins opener.) He’s vocal about wanting something at Northtown that fits the area’s heritage. “It’s industrial. It should be something that’s simple and strong,” he said.

Community comments are being sought on the type and design of the planned bridge at an April 9 open house, to be held from 5:30-7:30 p.m. at 2919 Randolph St. NE.

Bike and pedestrian friendly

Bridges aren’t a new issue here. The Northern Pacific railroad built the first crossing in 1910-1911, with the understanding with the city that the railroad would erect a permanent bridge in five years. But it took close to 15 years. And even then, Park Superintendent Theodore Wirth grumped that it and nearby parkway bridges weren’t “of a design worthy to be called a park bridge but they were the best that could be procured from the railroad companies without expense to the Park Board.”

The new bridge will offer parkway amenities, including a 10-foot-wide sidewalk and a 14-foot-wide bike path, both conforming with state standards, rather than the current cramped spaces where bikers are supposed to dismount.

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