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Commercial St Bridge
Penn Lincoln Parkway East over Commercial St
Commercial St Bridge
USGS 7.5" Topo Quad - UTM Coordinates:
Pittsburgh East - Zone 17; 0592 4475
-- Parkway East [I-376, US22, US30], four lanes divided
-- Commercial St
-- Nine Mile Run
TYPE OF CONSTRUCTION / DESIGN:
Reinforced concrete open spandrel deck arch [3 spans];
Reinforced concrete deck beam [6 western approach spans; 6 eastern approach spans]
LENGTH OF MAIN SPAN:
170 ft [3 arches];
28 ft [12 approach spans]
TOTAL LENGTH (including longest elevated ramp):
846 ft [15 spans]
HEIGHT OF DECK:
85 ft clearance at arch [68 ft deck width]
YEAR ERECTED / ENGINEER:
1951, PA Dept of Highways
The Commericial St Bridge looks like the cereal-box version of the George Westinghouse Bridge -- a scale model for action figures and die-cast cars. But typically this bridge is seen only from the short cut between Forward Av in Squirrel Hill and Whipple St in Swissvale as Commerical St winds through a much ignored part of Frick Park. Grander plans for the development of the southern part of the park have long been hampered by the looming slag pile and the maze of sewer lines in the Nine Mile Run valley. A 1938 pictorial map of the park shows two pair of low speed ramps leading to Commercial St from the "proposed Lincoln Highway Bypass."
Material excavated during the construction of the Squirrel Hill Tunnel fills a part of Nine Mile Run valley to a depth of 100 feet on a 1,000 foot long approach to the Commericial St Bridge. In 15 spans, the viaduct carries the Parkway East about 100 feet above Nine Mile Run. The 68 foot wide structure is in fact a pair of twins -- each featuring two-ribbed arches. The transverse arches connecting the ribs and the massing of the piers seem to hint at Gothic touches.
The columns for the western approach are carried on reinforced concrete beams lying on the slope of the fill which in turn are supported by columns which reach bedrock.
Constructed between April 1948 and April 1951 at a cost of $1,780,000 by Dinardo Inc of Pittsburgh, the bridge includes nearly 2.5 million pounds of steel reinforcing bars and 15,000 cubic yards of concrete.
1953 PA Dept of Highway report
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