This is based on a bridge over the American River on the California Central Railroad.
It was built in 1860 but after a few years partially due to a lack of maintainence it
developed a 3-1/2 ft sag in the middle of the main span. Crews were understandably
afraid to cross it. On August 23, 1871 it collapsed in the river. Besides the lack of
maintainence the failure was due to the material used to construct the bridge. Wood
works well in compression but not in tension. The design itself (a lenticular truss)
is good although this was a bit longer then usual. Subsequent bridges of this design
used iron rods for the tension members and held up quite well.