Thursday, February 24, 2011

The bridge

Tempe, AZ and the SP bridge is truly grand. The Salt River Union Pacific Bridge is significant not only because of its age and size, but also because of is durability in the face of heavy flooding, which destroyed three previous bridges in this location. It is on the site of the earliest railroad crossing of the Salt River. The first railroad bridge, built by the Phoenix and Maricopa Railroad at this crossing in 1887, was washed away in 1891. The second bridge fell victim to a flood in 1905. During 1905, the newly organized Arizona Eastern Railroad built a bridge on a slightly different alignment. It was founded on ten sets of concrete-filled steel cylinder drums anchored in the bedrock of the river. The nine spans were moved to the site from various locations in Texas, creating a workable but temporary structure. The present bridge was built by the Arizona Eastern in 1912-1913 on the old 1905 piers, but with nine through truss spans manufactured by the American Bridge Company. This structure has since dependably served the railroad for seventy years. During the recent floods of 1980-1981, when most crossings of the Salt River were closed, the commuter train "Hattie B" was able to take workers from the east valley to Phoenix via the Salt River Southern Pacific Railroad Bridge (its name before the recent acquisition of Southern Pacific by the Union Pacific Railroad).

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