Posts tagged with "Minneapolis":

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Bridge 5721: Historic Restoration and Relocation

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Laser scanning technology helped a Minnesota bridge find its third home

One of 24 historic bridges chosen for preservation by the Minnesota Department of Transportation, Bridge 5721 is one of the state’s only remaining wrought iron bridge structures. The bridge was originally built to carry pedestrians over a river in Sauk Center, Minnesota, in 1870, before modern steel production methods had become available. In 1937, the bridge was disassembled and moved to span the Little Fork River near the town of Silverdale. But more than two years ago, the structure began its journey to a third incarnation, this time as an equestrian and pedestrian bridge for the Gateway Trail in the town of Stillwater, near Minneapolis. Because of the bridge’s provenance and the desire to keep its wrought iron parts intact, the Minnesota DOT worked with new owner Minnesota Department of Natural Resources and structural engineers at HNTB and Olson & Nesvold Engineers (O.N.E.) to collect crucial data for the rehabilitation using new 3-D laser scanning technology.
  • Fabricators White Oak Metals (steel); HNTB, Olson & Nesvold Engineers (O.N.E) (design)
  • Engineers HNTB, Olson & Nesvold Engineers (O.N.E) (design)
  • Location Stillwater, Minnesota
  • Status Complete
  • Materials Steel, lightweight concrete
  • Process 3-D laser scanning, steel fabrication, historic restoration, relocation
While the project’s main goal was to preserve the 162-foot-long bridge’s historic character, the team nevertheless recognized that certain parts would have to be replaced to ensure the structure’s safety and longevity. Because original plans for the span were unavailable, MN DOT surveyors used a Leica laser scanner to create a 3-D map of the structure before it was disassembled. The scanner fires a laser more than 50,000 times per second, collecting data from reflected light. Placing the camera in nine different locations over the course of two days, the team collected more than 13,000 million data points with x, y, and z coordinates. After each truss member was removed, it was placed on a scanning table and fastener patterns were scanned. The geometric data created a point cloud of the bridge, allowing the team to isolate specific members or generate and view sections even after the span was dismantled and put into storage. See a video of the laser scan below: The team also made detailed drawings of two floor beams to be replaced at either end of the structure. These were given to steel fabricator White Oak Metals, who was able to create new beams that would fit into the structure with the original connections. Other updates included the replacement of roller nest bearings with elastomeric bearings and replacement of 10 steel stringers that had been added after the 1937 move. The 17-foot-wide wooden deck was replaced with lightweight concrete deck to minimize the structure’s dead load. Photos taken more than 100 years ago show that the bridge’s portals originally had a clearance of 14 feet. These had been raised two feet after the move to Silverdale. Using their laser scans, the team determined the fastener patterns of the existing portals and used these to detail replacement portals that would return the bridge to its original clearance. Once steel fabrication was completed last year, erection crews reassembled each truss on the ground in its new Stillwater location. Two cranes slid it into place on new concrete abutments, then the concrete deck, safety railing, and a new four-coat sealing paint system were added to ensure the structure’s continued longevity under its new title, Bridge 82524. See a video of the installation below:
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Minneapolis Riverfront Redesign Team Selected

The Berkeley, California and Boston-based team of Tom Leader Studio and Kennedy & Violich Architecture has won a competition for the potential redevelopment 5.5 miles of the Minneapolis Riverfront. Their proposal, called RiverFIRST bested those by rivals Ken Smith, Stoss Landscape Urbanism, and Turenscape, and includes constructed wetlands for stormwater management, manmade islands for habitat, new districts for green industry among other features. While no specific segment of the plan has yet been identified for development, the team will be given a commission by the Minneapolis Parks and Recreation Board.

Metrodome Roof Gets Remixed

We told you yesterday about the sad state of Minnesota's snowy Metrodome. Today the deflated dome gets some funk, courtesy of University of Minnesota arch school grad Brice Aarrestad. (Insert your own 'raise the roof' joke here.)

Metrodome Deflated

Following a heavy snow storm this weekend, the roof of the Minneapolis Metrodome collapsed. This video shows the structure creaking under the weight, the roof fabric tearing, and snow pouring in on the field. It looks like a scene from The Day After Tomorrow. Blair Kamin was quick to point out that though the stadium was designed by the Chicago office of SOM, the roof was the work of New York-based Geiger Berger Associates. Buffalo, New York-based Birdair Structures maintains and supplies the roof fabric. No one was hurt in the collapse. According to the Minneapolis Star-Tribune, this is the fourth time roof has ripped and deflated. Officials are still determining how low it will take to repair the structure.
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The Skyway's the Limit

As architects struggle to find work, a good place to turn has been the "green" market, especially adaptive re-use ("weatherizing," as the president likes to call it). Well, here's an extreme case: On Friday, Curbed noticed a proposal by Minneapolis firm City Desk Studio to transform a skyway into, among other things, a lakeside retreat. Better yet, it was being offered on Craigslist. For $79,500. Our jaws firmly dropped, we decided to call the firm up to find out more. Partner Bob Ganser answered in his polite, Midwestern way (sadly sans a Fargo accent) and admitted the firm was shocked by the response. "It's been viral, to say the least," he said. Perhaps the only thing more impressive than the proposal itself is the fact that the firm had posted it on and off on Craigslist all year, and it just happened to explode this time around. "There was one small story in a weekly financial paper here," Ganser said. "And then it just caught fire within a week." All the better, given that all the flood of interest has generated dozens of responses, about half of which Ganser said were real, serious offers. The story's even made as far as the UPI. "It's the News of the Weird, but we'll take it," Ganser said. "It is pretty wild." The firm, made up of Ganser and two fellow Golden Gophers, first heard about the bridge sale through an RFQ listserv run by their alma mater. When they placed their blind bid, it turned out no one else had, so the skyway was theirs. They attached wheels and moved it a matter of blocks to land currently leased from the city. (Some prospective buyers are far-flung, and transport has proven the greatest impediment to those deals, Ganser said.) Once the firm had the skyway, Ganser said they struggled to decide what to do with it. Minnesota being the land of 10,000 lakes, they eventually settled upon a lake house. "When we first heard about it, we though it would be some piece of junk," Ganser said. "But it turned out to be a beautiful piece of engineering. We thought it could be our own Glass House." It's not that much of a stretch, either, given that the span's designer, "father of skyways" Ed Baker, worked with Philip Johnson. He said the firm did realize they would need partners to complete the project, so they devised a time-share with a dozen slots at $100,000 a pop. They even put together a sales procure [.PDF]. When the partners canvased friends and family, there was some interest, but never a critical mass, so they turned it over to Craigslist, where the most recent ad has caused such a commotion. While the firm proposed such uses as a wine bar and an "inhabitable billboard," Ganser said those now interested in the project have mostly hued towards cabins and artist studios, as well as people seeking home additions, though Ganser believes that would a far more difficult undertaking than a stand-alone building. A number of local municipalities have also expressed interest. And, for better or worse, a number of architects who are themselves in need of a skyway for one of their own projects have called about buying it. "We would certainly like to see it transformed into some other use," Ganser said. "In a perfect world, we'd be the architects, too, but above all else, we want to see it get some use." As for moving the skyway, Ganser said he hopes it stays local, given that Minneapolis is the birthplace and, arguably, capitol of these architectural appendages. "In a way, it's a special object," Ganser said. "It has a special character. It's not just being reused. Especially in this area, it's place defining. It's almost mythical."