The following is an update on the National Transportation Safety Board's investigation of the I-35W bridge collapse in Minneapolis, Minnesota on August 1, 2007.
The NTSB investigation of the I-35W bridge collapse continues. Approximately 30 investigators are working on-scene and at headquarters to determine the probable cause of this accident. Minnesota Department of Transportation (MNDOT), the Federal Highway Administration and other parties continue to assist in this investigation.
"Since the start of this accident investigation, we have made substantial progress, in recovery, documentation, and data gathering," said NTSB Chairman Mark V. Rosenker. "However, several of our investigators are still on-scene and we are in the midst of a complete and thorough analysis of this information."
On Friday, October 12, NTSB investigators completed their work at the location of the bridge collapse and released the site to MNDOT.
NTSB investigators are conducting a detailed examination of the failed bridge structure. Bridge components relevant to the investigation are being kept at Bohemian Flats, a restricted, secure location south of the collapse scene. Principal components of particular interest will be shipped to the NTSB when the on-scene work is concluded.
"As part of its investigation, Safety Board investigators are meeting with persons who were on the bridge at the time of the collapse," said Rosenker. These individuals are reviewing a diagram of the I-35W Bridge that include vehicles and equipment in estimated pre-collapse locations to refine estimates of the loading of the bridge.
"The NTSB's on-scene phase of the investigation is expected to conclude in late November," said Rosenker. "However, as the investigation continues, investigators will visit Bohemian Flats for further evaluation of components from the bridge, if that should be necessary. "