This bridge was one of the most unusual examples of a skewed concrete to be encountered. Its uncommonly extreme skew was accommodated in an uncommon manner. The bridge was separated into a series of five stepped rib-like arch sections that were offset from each other, forming the skewed configuration. The Historic Bridge Inventory, amazingly, dismissed this as not noteworthy. However, HistoricBridges.org strongly disagrees with such an assessment, since the design was a creative way of producing a skewed bridge without the complicated engineering and construction needed for a traditional, true skewed arch bridge. It is also far more rare than the phrase "less common" used by the Historic Bridge Inventory.
This bridge now joins the staggering number of historic bridges demolished by PennDOT in the 21st Century.
Information and Findings From Pennsylvania's Historic Bridge Inventory
Discussion of Bridge
The single span, 146'-long, reinforced concrete deck arch bridge built in 1931 by the state highway department has five staggered, stepped ribs, a construction technique to accommodate the extreme skew. The technique has been used with masonry arches since ancient times, and it is not innovative or technologically noteworthy. The bridge is finished with concrete balustrades and paneled pilasters at the abutment corners. The arch rings and intrados are spalled with exposed reinforcing bars. The reinforced concrete deck arch type was widespread in Pennsylvania by 1910, and over 270 pre-1920 examples have been identified. This later example, although of a less common stepped construction to handle the skew, has no innovative or technologically noteworthy qualities.
Discussion of Surrounding Area
The bridge carries a 2 lane road with shoulders over 1 active track of the Union Railroad in an industrial area 2000' north of the Allegheny County Airport. A second track has been removed. The Union Railroad was the intra-plant railroad for US Steel. This section of the line from Monongahela Junction to Mifflin Junction was established in 1906.
Bridge Considered Historic By Survey: No
This historic bridge has been demolished. This map is shown for reference purposes only.
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