|Commissioning Entity||The City of Pittsburgh|
|ADA Services||The bridges have pedestrian walkways on both sides of the roadway. There are curb cuts at the sidewalk to access the walkways.|
Pittsburgh’s current downtown bridge trio actually hints at a longer history of river spans. The first bridge across the Allegheny was the St. Clair Bridge of 1819 at the site of the current Sixth Street structure. The Hand Street Bridge followed in 1840 at the current Ninth Street Bridge site. John Roebling built a new, sturdier bridge at Sixth Street in 1859, something of a precursor to his later Brooklyn Bridge. Subsequently, the lesser known, but similarly ambitious Gustav Lindenthal built a bridge at Seventh Street in 1884 just before completing his Smithfield Street Bridge across the Monongahela, which still stands.
Roebling and Lindenthal were unusual engineers whose designs were genuinely beautiful, but many other nineteenth and early twentieth century bridges were utilitarian structures of ungainly appearance. The notion to consider them as aesthetically pleasing civic art only took hold in the early twentieth century, beginning in New York and spreading nationally. Construction of the Three Sisters Bridges between 1926 and 1928 involved various consolidating forces that allowed them to be considered and built as a single ensemble.
An Allegheny County bond issue funded the structures, replacing the tenuous economics of the individual, private, for-profit toll bridges that had previously occupied these established sites. Meanwhile, the rise in commercial navigation led to the mandate of a 47-foot clearance for the bridges. Also, a recent requirement that Pittsburgh’s Art Commission review the designs guaranteed an artistic and architectural review of their design.
The Allegheny County Department of Public Works produced the designs with Vernon R. Covell as chief engineer, and Stanley L. Roush as architect. The generally familiar shape of the suspension bridge is actually an unusual design here. The bridges are self-anchoring rather than ground or abutment-anchored, the first of their kind in the country. They also use eye-bar chains rather than cables, another unusual feature.
The results have been consistently viewed as successful. The American Institute of Steel Construction called the Sixth Street Bridge (the first to be completed) the Most Beautiful Steel Bridge of 1928. In recent years, the Sixth Seventh and Ninth Street Bridges have been renamed for Roberto Clemente, Andy Warhol, and Rachel Carson respectively, reinforcing their adaptability and continuing relevance.
By Charles L. Rosenblum
The Allegheny County Department of Public Works produced the designs with Vernon R. Covell as chief engineer, and Stanley L. Roush as architect.