Three Sisters (Pittsburgh)
The Three Sisters are three similar self-anchored suspension bridges spanning the Allegheny River in downtown Pittsburgh, Pennsylvania at 6th, 7th, and 9th streets, generally running north–south. The bridges have been given formal names to honor important Pittsburgh residents:Roberto Clemente
Andy Warhol
Rachel Carson
View of Sixth, Seventh and Ninth Street Bridges from downriver
From north bank of the Allegheny, downtown Pittsburgh in background
From north bank of the Allegheny, looking SW, downtown Pittsburgh in background, Sixth Street Bridge at right. Shows main plate girder (bearing compressive forces) and sidewalk support
From south bank of the Allegheny, looking NE, oblique view of roadway and south tower, showing eyebar links for main suspenders and roadway suspenders, as well as solid plate main compressive stiffening girders dividing roadway from sidewalks
Self-anchored suspension bridge
A self-anchored suspension bridge is a suspension bridge type in which the main cables attach to the ends of the deck, rather than directly to the ground or via large anchorages. The design is well-suited for construction atop elevated piers, or in areas of unstable soils where anchorages would be difficult to construct.
The main span of the eastern span of the San Francisco–Oakland Bay Bridge, the largest example of a self-anchored suspension bridge in the world.
The Three Sisters (Pittsburgh), the first self-anchored suspension spans, opened in 1926 to 1928.
Hutsonville Bridge cable anchor detail
