On Dec 8, 12:07*pm, whensenseless mumbled incoherently:

http://en.wikipedia.org/wiki/De_Havilland_Comet

The world owes a great debt to De Havilland for discovering metal
fatigue in aircraft. The Americans wanted to be first (as usual) but
they were still flying biplane stringbags at the time. Spruce just
doesn't fatigue so easily... as all geese know.

That bridge wasn't brought down by traffic so much as the increasing
weight of the vehicles' occupants. The resonant frequency of all those
Mr and Mrs Blobbies bouncing up and down, excited by the raised
expansion joints, had a similar effect to troops marching in step
across a bridge. It couldn't cope with the (un)sympathetic vibration.