This bridge was originally built as a double-deck bridge with highway (on top) and railroad bridge (on bottom). Unfortunately, by the time this bridge was documented by HistoricBridges.org in 2016, a project to demolish nearly all of the long-abandoned highway deck was nearly completed, although some noteworthy highway portions remained on the approaches. Despite this loss, the remaining bridge is still one of the longest and most complex bridge systems in the country. HistoricBridges.org is proud to offer detailed coverage of not just the well-known Mississippi River spans, but also the lesser known but noteworthy approach sections.
The Mississippi River spans with their 668 foot spans (center to center of pins) or 772 feet (overall length) are among the longest simple truss spans in the entire country. This fact, combined with the unusually heavy double-deck design make this bridge a highly significant engineering feat.
One of the approach spans in particular is extremely unusual: the half-through truss span. The truss span is designed with three truss lines. The two northern truss lines supported the highway deck on top as a true deck truss. The southern two truss lines support the railroad line about halfway up the truss height, forming a rare half-through truss layout. To add to the unique design, the northern truss line is a Baltimore truss, while the other two truss lines are Pratt trusses.
Early investigations for locating this bridge were prepared in 1907 including input from two famous engineering firms, Ralph Modjeski and Waddell and Harrington.
Above: Historical construction photo showing main span construction.
Above: Historical construction photo showing 70 foot end post section shipped to site.
This bridge is tagged with the following special condition(s): Double-Deck
Additional Coordinates: Mississippi River Spans: 38.61477, -90.18391 Half-Through Truss Span: 38.61212, -90.17379 Railroad Pennsylvania Truss Span: 38.60988, -90.16562 Highway Pennsylvania Truss Span: 38.61347, -90.16617 Broadway Trusses: 38.61767, -90.19324
Coordinates (Latitude, Longitude):
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