Crossing the Mississippi

This article describes the design and construction of the new St. Anthony Falls Bridge in Minneapolis, which is being built to replace the I-35W Bridge that collapsed in August 2007. The St. Anthony Falls Bridge was designed, with community input, to complement Minneapolis's natural surroundings and urban architecture. The final bridge design consists of two parallel structures, each with two concrete box girders. Ten lanes of traffic are accommodated in the design. Each of the 70-foot-tall concrete main piers was cast in place and is founded on multiple drilled shafts that are socketed into rock. High-strength, high-performance concrete is used throughout the bridge. The posttensioned bridge features bi-directional prestressing of the deck. The service life of the bridge is expected to be more than 100 years. Sensor-based monitoring systems are incorporated in the bridge to provide information to support construction activities and record structure behavior. Bridge construction currently is more than two months ahead of schedule, and the bridge should be completed by mid-September 2008.