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MnDOT awards I-35W bridge replacement contract

ST. PAUL, MINN.—The Minnesota Department of Transportation (MnDOT) awarded a contract to Flatiron-Manson, a joint venture, for design and construction of the Interstate 35W bridge-replacement project. FIGG Bridge Engineers, Inc., is also part of the team. The I-35W bridge across the Mississippi River in Minneapolis collapsed on Aug. 1, killing 13 motorists and construction workers.

The primary theme outlined in the winning team’s design proposal is "Arches, Water, Reflection." According to MnDOT, "the proposal includes a signature bridge, lighting, and landscaping that seeks to paint an archway over the Mississippi River while respecting the area’s surroundings, history, and the architecture of nearby bridges and buildings."

Bridge design highlights include the use of prestressed high-performance concrete box girders; multiple levels of redundancy, including two independent structures, each with its own foundation system anchored in bedrock; and a state-of-the-art sensor and monitoring system.

Public involvement
At press time, Linda Figg, president, CEO, and director of bridge art for FIGG and the project’s visual quality manager, expected to lead a late-October community design charette to choose final bridge aesthetic features such as pier shape, color, bridge railing, gateway monuments, feature lighting, and landscaping. "In addition to designing the best and safest bridge, we want to create a bridge that reflects the values of this community," Figg said.

During FIGG’s Bridge Design Charette, participants are assembled and follow a set agenda. Options for specific bridge elements are presented and explained. A copy of the information is distributed to participants, who are encouraged to discuss the options. Once discussion is complete, participants vote on that particular aspect of the bridge. On-site computers tally the results, which are then shared with the entire group and used to finalize the bridge design. Separate design charettes will be held with the community on a memorial for those killed in the tragedy.

Public involvement is expected to continue during construction. Kiosks around Minneapolis will document the construction process, explain activities underway, and preview upcoming activities. The design/build team will hold weekly, informal question-and-answer sessions about current and upcoming construction activities. In addition, webcams installed on site will provide continuous public observation of the project.

Educational outreach is also included in the rebuilding process. The designer will provide FIGG Bridge Boxes, specially created educational tools for schools. Education web feeds to classrooms in real time from the construction site and weekend classes for children will be provided through the Science Museum of Minneapolis. Engineering students at the University of Minnesota will receive quarterly design and construction updates.

Flatiron expected to break ground on the $234 million replacement bridge in late October. It is scheduled to be opened to traffic by Dec. 24, 2008. More design information and construction updates are available online.