OFFICIAL NAME:
Seventh Street Bridge
OTHER DESIGNATION:
LOCATION:
Pittsburgh
USGS 7.5" Topo Quad - UTM Coordinates:
Pittsburgh West - Zone 17; 0584 4477
CARRIES:
Seventh Street
BETWEEN:
-- Sandusky St on right descending bank of Allegheny River
-- Seventh St and Fort Duquesne Blvd on left descending bank of Allegheny River
CROSSES:
-- Allegheny River at mile 0.6; Tenth Street Bypass
TYPE OF CONSTRUCTION / DESIGN:
Self-anchored Suspension
cables are steel eyebar chain
steel eyebar suspenders
steel plate girder deck
rusticated ashlar piers
LENGTH OF MAIN SPAN:
422 ft clear span
TOTAL LENGTH (including longest elevated ramp):
1061 ft
HEIGHT OF DECK:
40.1 ft
Emsworth Dam normal pool level 710 ft
YEAR ERECTED / ENGINEER:
1925-26, County of Allegheny
Vernon R. Covell, T.J. Wilkerson, A.D. Nutter, and H.E. Dodge of the Allegheny County Department of Public Works, engineers; Stanley L. Roush, architect
Allegheny County, current owner
ADDITIONAL INFO:
One of the "Three Sisters." Municipal Art Commission mandated suspension as form of the bridges, but site conditions did not allow for typical anchorages. Bridges were built as cantilevers until catenaries were completed.
In a very unusual, self-anchored suspension design, instead of heavy anchorages to hold the cable ends, rigid towers hold the ends apart. First of this type in US.
Deck girders were previously painted green and remaining superstructure was painted aluminum grey. Most downtown Pittsburgh river bridges are currently painted golden yellow (the official city colors are Black and Gold).
Replaced a two-span suspension bridge (1884-1925) which had truss-bracing on catenaries holding two eyebar-chain cables in concentric arcs. This previous bridge was designed by Gustav Lindenthal three years after he built the Smithfield Street Bridge.
Seventh St was formerly Irvine St (or Irwin St) in Pittsburgh; it aligns with Sandusky St in the former city of Allegheny (Northside).
Field Notes provide additional technical information.
view page - "Three Sisters" Bridges -- Historic American Engineering Record document
Plaques mounted on the utility houses near the ends of the bridge:
|
Seventh Street Bridge |
| Erected 1925-1926 |
| Allegheny County |
County Commisioners
Joseph G. Armstrong - 1925-26 - Chairman
Edward V. Babcock - 1925-26
James Houlahen - 1925--26
Addison C. Gumbert - 1925 |
County Controller
John P. Moore |
Department of Public Works
Director - Norman F. Brown
Assistant Director - C. M. Reppert
Chief Engineer - V. R. Covell
Chief Design Engineer - A. D. Nutter
Construction Engineer - A. A. Henderson
Consulting Engineer - T. J. Wilkerson
Architect - Stanley L. Roush |
Contractors
Substructure - The Foundation Co.
Superstructure - American Bridge Co.
Paving Contractor - M. O'Herron Co.
Electrical - Delmer Electric Co.
Utility Houses - W. F. Trimble & Sons Co. |
|
|
Historic Landmark |
Seventh Street Bridge
Department of Public Works,
Allegheny County, Engineers
1926 |
Pittsburgh History &
Landmarks Foundation |
|
FIELD CHECKED:
09-Jul-1999, 02-Jul-2001
INFO SOURCES:
Comm. of PA, et. al.: "Historic Hwy Bridges"; Kidney: "Landmark Architecture"; USACE Allegheny River Nav. Charts
