Collapse on the Mississippi

Where were you when the I-35 bridge collapsed?
Where were you when the I-35 bridge collapsed?Courtesy Tomruen on wikimedia commons

On August 1, 2007, in middle of the afternoon rush hour, the I-35W bridge collapsed. The central span of the bridge fell 115 feet into the Mississippi River; the adjoining spans fell just moments later. The accident caused 13 deaths, and injured over a hundred other people.

At the time of the collapse, much of the bridge was undergoing resurfacing. The structure supported more than half a million pounds of construction equipment in addition to the weight of afternoon traffic. Despite these stresses, however, the National Transportation Safety Board determined that the cause of the collapse lay with a faulty design element: The bridge’s gusset plates—large metal sheets connecting the steel girders that supported the structure—were both corroded and too small for the load the bridge was meant to carry.

“Creating bridges as art” is Figg Engineering’s philosophy. In addition to facilitating safe and efficient transportation, the new St. Anthony Falls Bridge is meant to fit aesthetically with the city and the surrounding environment. The tall, inward curving piers will frame the river, and will emphasize openness, with walkways and green space far beneath the smooth box girders.
“Creating bridges as art” is Figg Engineering’s philosophy. In addition to facilitating safe and efficient transportation, the new St. Anthony Falls Bridge is meant to fit aesthetically with the city and the surrounding environment. The tall, inward curving piers will frame the river, and will emphasize openness, with walkways and green space far beneath the smooth box girders.
Courtesy Figg Engineering

We can rebuild you. Better, stronger… smarter

Figg Engineering is committed to making the new bridge strong, safe, and "smart." With ultra strong materials and building techniques and a high-tech monitoring system, Figg intends to build a bridge that will safely last 100 years—twice the expected lifespan of the previous bridge.

Thirty-two shafts sunk fifty feet into the bedrock below will anchor the piers of the bridge. (The high performance concrete in the shafts will be strong enough to support 91 fully loaded passenger planes!) Wider than the old bridge, the new one will have room for bus lines or light rail, and each direction of traffic will travel on its own independently supported platform. The segments making up the central span across the river will be linked by hundreds of high-strength steel cables, with full-length strands running from one end of the bridge to the other.

Sensors embedded in the structure of the bridge will provide continuous information about the bridge’s structural behavior. And weather stations and deck sensors will turn on built-in chemical sprayers to keep the surface from icing up in the winter. All of these machines will let bridge engineers know if the bridge is acting unusual, so repairs can be made long before anything goes wrong.