A day after the tragic collapse of the 35W bridge in Minneapolis, theories of exactly what caused it began pouring out of the Twin Cities area. Perhaps the most disturbing piece of news surfacing is the fact that Minnesota Department of Transportation (Mn/DOT) officials knew there was serious corrosion on bearings and steel but still deemed the bridge fit to hold traffic. Experts say that corrosion could have restricted the structure from moving freely as it was designed to do. Officials also knew of decay and fatigue cracking in the deck truss and other places.
Attempts to reach Mn/DOT over the past couple of days have been unsuccessful.
A security video showing the entire collapse as it happened also was released yesterday and should help investigators pinpoint the exact cause. Before the video, officials were literally grasping at straws in an attempt to determine a breaking point. A computer model of the bridge also should serve as a valuable aid.
The NTSB hopes to salvage crucial parts of the downed bridge and reassemble them over the next few weeks. Hardcore conclusions, however, could take months to develop.
