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picture of bridge

View east from Big Sewickley Creek Rd (downstream right)

More detail photos

OFFICIAL NAME:
Allegheny County Bridge Number 6 Big Sewickley Creek [SB06]

OTHER DESIGNATION:
Big Sewickley Creek Rd [old alignment] over Big Sewickley Creek
ambr572-3

LOCATION:
Franklin

USGS 7.5" Topo Quad - UTM Coordinates:
Ambridge - Zone 17; 0572-4496
CARRIES:
Big Sewickley Creek Rd old alignment
adopted as private drive at 2775 Warrendale and Bayne Rd

BETWEEN:
-- Warrendale and Bayne Rd [Red Belt]
-- private residence

CROSSES:
-- Big Sewickley Creek


TYPE OF CONSTRUCTION / DESIGN:
riveted steel plate girder
abutments: locally-quarried sandstone, rock-faced coursed ashlar



LENGTH OF MAIN SPAN:
ft

TOTAL LENGTH (including longest elevated ramp):
ft

HEIGHT OF DECK:


YEAR ERECTED / ENGINEER:
1900, Allegheny County
Charles Davis, engineer


ADDITIONAL INFO:
A metal builder's plaque is riveted to the western end of the downstream girder:

ALLEGHENY COUNTY
J.C. MERCER,
W.W. MURRAY
J.A. CLARK
COMMISIONERS
C. DAVIS, ENGINEER
W.E. THOMPSON CONTROLLER
BUILT BY
PITTSBURG BRIDGE CO
1900




During years surrounding 1900, Allegheny County, under the direction of County Engineer Charles Davis, was busy throughout the county building stone arch bridges of a simple and similar design. In some places, however, the crossings were built as riveted plate girder spans. The abutments of these girder bridges exhibit similar stonework to the County's stone bridges -- helping to identify their place in time and origin. A glance at the construction dates indicates that many of the earlier bridge were of the girder type.

One possible explanation for the choice of an arch span versus a girder span may be found in the shape of the land onsite. Where the stream has high banks and can therefore hold rising waters of a flash flood, the bridges are usually stone arches. In places with relatively wide, flat channels, the spans are most often girders. In each instance, the goal was to maintain the level of the road surface as the road approaches and then enters the bridge -- while allowing maximum potential stream flow; sites which made this impractical have since been regraded or replaced.

Allegheny County assigns its bridges with an ID number counting from a stream's outflow, sequentially upstream. Because of its age, this bridge defies the system. Tracing Big Sewickley Creek upstream from the Ohio River near Ambridge, one finds many bridges have been added as the road meanders through several realignments. A cast number plate identifies this bridge as "6" (Big Sewickley Creek Number 6). The next bridge upstream a few hundred feet is marked as "5" -- out of sequence. This is probably due the order of construction: the original courses of Big Sewickley Creek Rd and the old Pittsburgh-Rochester Rd were on the eastern side of the creek.

Rochester Rd extended from near Pittsburgh (Millvale area) to Rochester in Butler County; it was apparently a popular alternative to the Beaver Rd along the Ohio River. The c1900 USGS topo maps of the area show the old placement of the roads. Big Sewickley Creek Rd was relocated westward in 1929 as part of the upgrading for the Belt Route System; the section Pittsburgh-Rochester Rd crossing into Beaver County fell into disuse; and the pair of near-twin girder spans over Big Sewickley Creek were given over to be used as driveways to private residences.

view page - Pittsburgh-Rochester Rd over Big Sewickley Creek [SB05].

Due to the relative seclusion of this corner of Allegheny County, several older bridges can be found nearby -- illustrating the changing technology at 10 year intervals. A little over one-half mile south of these 1900 girder bridges, off Big Sewickley Creek Rd, Brown Rd spans the East Branch of Big Sewickley Creek with one of Davis' earliest stone arch bridges [1891]. North of these girder bridges along Warrrendale & Bayne Rd, a pair of concrete bridge span Big Sewickley Creek. The bridge on Spang Rd was built in 1910 as one of the earliest examples of what replaced Davis's stone arch bridges. A similar bridge at Markman Park Rd shows the concrete arch design still in use ten years later.

FIELD CHECKED:
7-Oct-2002

INFO SOURCES:
field check, cited maps


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Introduction -- Nearby Structures


Page created: 01-Apr-2003
Last modified: 01-Apr-2003

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