This evening's collapse of the eight-lane Interstate 35W bridge in Minneapolis remains unexplained, but it's clear from the pictures that the damage is horrendous.
The major artery between Minneapolis and St. Paul, crossing 1,000 feet of the Mississippi River, came down in three sections, dropping 60 feet into the water, part of it onto a freight train passing along the banks. It was during rush hour, around 6pm, though reports have the number of cars that fell into the water at only 50. Thus far the death toll is at 7, with 38 injured.
The bridge was being repaired at the time of the collapse, but what exactly caused 1,000 feet of steel and concrete to calve in three is unclear. A civil engineering study at the University of Minnesota in 2001 found that the bridge's steel girders were "susceptible to fatigue cracking." Still, more recent studies found that the bridge did not need replacing.
Minnesota governor Tim Pawlenty called the collapse a "catastrophe of historic proportions" and Minneapolis mayor R.T. Rybak said that he was concerned that it could "be a very tragic night when this is over."