Investigation into bridge collapse continues
The National Transportation Safety Board (NTSB) released in March more details about factors that may have led to the Aug. 1 collapse of the I-35W bridge. The ongoing investigation continues to focus on the half-inch-thick gusset plates, of which the NTSB released in March photos from prior to the collapse that appear to show bending that may have been a sign of imminent failure as early as 2003, reported the Star Tribune.
To this finding, the NTSB added in March that those too-thin plates may have been stressed by overloading on the bridge. More than 191 tons of rock and sand were piled on the bridge during the construction project that was going on when the bridge collapsed, reported the Associated Press in March.
The NTSB has not stated definitively the causes of the collapse; the full investigation is expected to be completed by the end of the year. That investigation will not include public hearings; in a close vote that drew criticism from some, including Rep. Jim Oberstar, the NTSB voted last month 3–2 to not hold such hearings.
last revised: April 24, 2008