Project Details

Managing JV Partner
Minnesota Department of Transportation
$234 million
October 2007
Start Date
September 2008
Completion Date

Building St. Anthony Falls Bridge

The St. Anthony Falls Bridge is a 1,216-foot-long, 10-lane concrete bridge with a 504-foot-long precast segmental main span. The bridge is supported by three land-based piers (four columns at each pier) standing 70 feet tall. Segments were cast on the south bank of the river on an existing closed section of I-35. There are 120 precast segments ranging in weight from 170 to 210 tons each.

Following the tragic collapse of the I-35W Bridge in Minneapolis in August of 2007, Flatiron formed a joint venture team to design and build the replacement bridge for the Minnesota Department of Transportation. After receiving the highest score on the proposal and subsequently winning the contract, the team mobilized quickly to begin work. Prior to its collapse, this bridge carried more than 140,000 vehicles a day. The loss of this vital link increased commuter expenses, created a burden on surrounding roads and costs approximately $400,000 per day in lost revenue.

The Flatiron team focused on building the best and safest bridge. Some of the highlights included the use of high performance concrete to provide superior durability, a state-of-the-art sensor and monitoring system built into the bridge that allows for easier and more comprehensive monitoring and a comprehensive safety program that was implemented throughout all aspects of the design and construction process. The bridge was completed and opened to traffic three months ahead of schedule.

New 1,216-foot-long precast segmental bridge

Highly accelerated schedule of just 14 months

Project award based on “best value”

504-foot-long main span over the Mississippi River

Associated General Contractors of America/Aon
Grand Award 2009
Design-Build Institute of America
National Design-Build Institute of America Award 2009
American Road & Transportation Builders Association
Globe Award for Environmental Protection and Mitigation 2009
American Public Works Association
Project of the Year 2009