Canadian Consulting Engineer
Bridge collapse spurs calls for action in U.S.Engineering
Fallout from the collapse of the 1-35 W Bridge in Minneapolis has been to shock the U.S. people into realizing the ...
Fallout from the collapse of the 1-35 W Bridge in Minneapolis has been to shock the U.S. people into realizing the poor state of their infrastructure.
After the bridge collapsed suddenly during rush hour on August 1 and fell 20 metres into the Mississippi River, blog commentators went to town on the internet. Many commentators used the tragedy to make political points, questioning why the U.S. was not spending more on repairing bridges, roads and water treatment plants, instead of investing in military efforts overseas. They were also quick to point out that government shortsightedness had contributed to the New Orleans disaster because it could have been prevented with better levees and flood protection.
By August 8, James Oberstar (Minn.), chair of the Committee on Transportation and Infrastructure for the House of Representatives, was proposing a plan of action. His National Highway System Bridge Reconstruction Initiative” called for the U.S. government to provide dedicated funds to states to improve and rehabilitate bridges on the national highway system. These bridges carry 70% of the bridge traffic in the U.S.
In a paper outlining the initiative, Oberstar pointed out that “According to the U.S. Department of Transportation, one of every eight bridges in the nation is structurally deficient.” It explained that of the 597,340 bridges in the U.S., 73,784 are structurally deficient. A footnote explained that a structurally deficient bridge “is a bridge that has major deterioration, cracks, or other flaws that reduce its ability to support vehicles.”
The initiative called for immediately improving the processes for inspecting bridges on the national highway system that had been found to be structurally deficient, and recalculating the load rating to ensure that the maximum weight limits are properly posted.
The Department of Transportation has estimated that $65 billion “could be invested immediately” in repairing bridges.
Meanwhile the National Transportation Safety Board with other agencies was investigating the possible cause of the 1-35 W collapse. They chairman of the investigating team reported they had observed a design issue with gusset plates and were investigating the loads and stresses on them at certain locations. The team was also investigating the location of construction equipment and raw materials on the bridge at the time of the collapse.
A professor at the University of Minnesota, Massoud Amin, was an eyewitness of the disaster, being about 200 yards from the structure. In a Scientific American online article dated August 3, he recalled, “The bridge fell first at the short span on the downtown side, then the main span went down first at the downtown end, and broke off the opposite side short span … which stood for a few seconds before the support buckled and it went down.”