Three Sisters Bridges, Spanning Allegheny River at Sixth, Seventh & Ninth, Pittsburgh, Allegheny County, PA

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Historic American Buildings Survey/Historic American Engineering Record/Historic American Landscapes Survey

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TITLE:
Three Sisters Bridges, Spanning Allegheny River at Sixth, Seventh & Ninth, Pittsburgh, Allegheny County, PA

CALL NUMBER:
HAER PA,2-PITBU,78-

REPRODUCTION NUMBER:
[See Call Number]

MEDIUM:
Data Page(s): 42 plus cover page

DATE:
Documentation compiled after 1968.

CREATOR:
Historic American Engineering Record, creator

NOTE:
Survey number HAER PA-490

Unprocessed field note material exists for this structure (N581).

Building/structure dates: 1924 initial construction

Includes extensive overview of predecessor bridges at these locations.
See also HAER PA-217 for related documentation. Includes photographs & written data.

Significance: These structures are the only trio of nearly identical bridges, as well as the first self-anchored suspension spans, built in the U.S. They are among the only surviving examples of large eye-bar chain suspension bridges in America, and furthermore unusual for having been erected using cantilever methods. The bridge's design was a creative response to the political, commercial, and aesthetic concerns of Pittsburgh in the 1920s.

SUBJECTS:
PENNSYLVANIA--Allegheny County--Pittsburgh
transportation
cantilever erection
public works

OTHER TITLE:
Trinity of Bridges

COLLECTION:
Historic American Engineering Record (Library of Congress)

REPOSITORY:
Library of Congress, Prints and Photograph Division, Washington, D.C. 20540 USA

DIGID:
http://hdl.loc.gov/loc.pnp/hhh.pa3845

CONTROL #:
PA3845

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