USGS 7.5" Topo Quad - UTM Coordinates:
Pittsburgh East - Zone 17; 0585 4477
Pennsylvania Mainline of Public Works [Pennsylvania Canal]
-- near Voeghtly St on right descending bank of Allegheny River
-- near Eleventh St [Washington St] on left descending bank of Allegheny River
-- Allegheny River at mile 1.0
TYPE OF CONSTRUCTION / DESIGN:
wooden Burr arch truss and aqueduct channel.
LENGTH OF MAIN SPAN:
162 ft clear span (also noted as 150 ft)
TOTAL LENGTH (including longest elevated ramp):
1092 ft (7 spans)
HEIGHT OF DECK:
YEAR ERECTED / ENGINEER:
1829; S. Lothrop
This was the first of five bridges near this location.
Designed by S. Lothrop, this wooden covered aqueduct was built in 1829 at a cost of $104,000. The overall width was 34 ft including pedestrian walk on one side and mule path on the other. The water channel was 15 ft wide at the bottom, 16 ft wide at the top, and 5 ft deep. It carried water at a depth of about 4 ft, 3 in. Each span was a Long-type wooden truss (similar to Howe) with Burr-type arches. There were 4 arches in each span: arch, walkway, arch, waterway, arch, mule path, arch. Most of the floor weight was suspended from the arches by 1-1/2" iron rods. The entire structure was covered by a low, peak roof.
Some sources list the 7 spans at 150 ft in length, however, the Roebling bridge presumably reused the existing masonry piers from the first bridge. The 7 Roebling spans are noted as having been 162 ft each.
The structure was part of the Pennsylvania Main Line of Public Works (Pennsylvania Canal) completed across the state in 1834. This line connected to a tunnel completed in 1829 at a cost of $61,000 under Grant's Hill and led to a pool near the Monongahela River. The canal tunnel's north portal was near the north portal of the Panhandle rail tunnel, which is now used as part of the Subway "T" system. But while the canal tunnel angled farther east to a south portal near Shingiss St and Diamond St., the railroad tunnel leads to a south portal near Forbes Av and Try St.
The wooden aqueduct was unable to withstand the constant loading of the water it carried. On at least one occasion, a portion of the trough fell out of one span and effectively empty the water from a large portion of the canal.
John Roebling, creator of the Brooklyn Bridge, Pittsburgh's second Smithfield St Bridge and second Sixth St Bridge, completed the wire rope aqueduct bridge in 1845 to replace the covered wooden structure.
These aqueduct bridges aligned with 11th St in the Triangle and Voeghtly St. on the Northside.
The drawings are a composite from historical sketches and photos.
As the railroad came to Pittsburgh, it was able to make the canal obsolete. The third bridge, built just downstream from the canal bridge, was a wooden truss structure built in 1857 for the Pittsburgh, Fort Wayne and Chicago Railroad.
field check; Shank, "Historic Bridges of Pennsylvania"; Lorant, "Pittsburgh"
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