NJT = New Jersey Transit
CSAO = Conrail Shared Assets Operations That means that both CSX and NS trains use it.
This bridge was built with a swing span in 1896. Rather than replace the movable span, they added a 542' lift span with 135' clearance next to it in 1960. The swing span has been taken out of service, but leaving it saved the the cost of removing the center pier of the swing span. It was the first bridge between Philadelphia and New Jersey. [Bridge Hunter] Another reason a lift span was built next to the existing swing span is that the US Army Core of Engineers dredged a deeper channel. [sjrail]
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| Photo from HAER PA,51-PHILA,720--2 from pa3755 |
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| Postcard from sjrail, cropped |
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| sjrail, cropped Deleware River Railroad and Bridge Company (Delair Bridge) circa 1890 |
In 1896, the Pennsylvania Railroad (PRR) was the first to accomplish the goal of spanning the Delaware River between Philadelphia and Camden, New Jersey. For three decades until the Benjamin Franklin Bridge opened to automobile traffic, the PRR's bridge (commonly known as the Delair Bridge) was the only crossing downstream of Trenton.
The lower Delaware's extreme width, tidal current, and soft bottom made foundation work difficult,
meaning that a successful design would need extremely long spans. When completed, the Delair
Bridge had 533'-0" Petit through trust spans. This was an impressive length for the time, albeit a
few feet shorter than the Chesapeake & Ohio's 1889 Ohio River bridge at Cincinnati, the record holder at 542'-6". Complicating the design further, heavy traffic on the lower Delaware required a high bridge, or else a movable one. PRR engineers compromised by building the fixed spans 50'-0" above the water and providing a swing span for the tallest vessels. The Delair Bridge is also significant for having set records at two widely separated points in its existence. In the mid-twentieth century, PRR retained Hardesty & Hanover to design a 542'-0' vertical lift span over a new navigation channel proposed by the U.S. Army Corps of Engineers. While setting a record for the longest vertical-lift bridge with two tracks, it was two feet shy of the overall record, set by the New York, New Haven & Hartford's single-track bridge at Buzzard's Bay, Massachusetts, in 1935. As a result, the Delair Bridge hosts an unusual combination of two different movable spans m one structure (although the swing span was subsequently taken out of service).
The Delair Bridge is 4,396' long, of which 2,453'-0" is riveted deck girder approach trestles. A lengthy trestle was necessary on the Philadelphia side to carry the railroad over city streets while climbin an 0.7-percent grade to the high truss spans over the river; the New Jersey approach is mostly earthen emabnkment. The girder spans are mostly 40', with some exceptions where the approach crosses Carbon Street (50'-3") and Delaware Avenue (77'-6") on the Philadelphia side. Each trestle bent is supported by four stepped granite footings on a wooden pile foundation. The shore piers, Nos. 1 and 6, are also carried on wooden pile foundations with 190 piles in each group, driven to bearing in a sand and gravel layer and capped capped with a timber grillage at 30' below water level. All of the river piers, Nos. 2 through 5, were excavated by Drake & Stratton using timber caissons; these were rectangular, except for a hexagonal caisson accommodating the cylindrical swing span pivot pier, No. 4. Pier masonry consisted of a concrete core sheathed in large granite blocks 18" to 24" thick, or 30" in the coping, with some blocks weighing more than 20 tons.
The river spans originally consisted of three 533'-0" pin-connected Petit through truss spans, one on the New Jersey side of the 323'-0" swing span and two on die Pennsylvania side. Invented by a PRR bridge engineer, the Petit (or Pennsylvania) truss is a variant o fthe Pratt miss, with diagonal members in tension, a polygonally curved top chord, and intermediate floor beams hung from a secondary diagonal system. The intermediate floor beams reduce the length of longitudinal stringers between panel points, making a more efficient structure capable of spanning up to 600'. The fixed trusses are 84'-0" deep at mid-span and divided into 66'-7-l/2" main panels, with intermediate floor beams at half that interval. In the swing span, a 60'-deep pin-connected Petit through truss, the six main panels are each 53'-4", with intermediate floor beams at 26'-8". Pencoyd Iron Works used a traveling gantry crane to erect the fixed spans, each weighing 2,091 tons, on temporary wooden falsework. The swing span (931 tons including machinery) was erected in the open position, using the fender pier as a working platform. Several sources, including PRR annual reports, describe the Delair Bridge as "an iron structure," but this is simply the persistence of a nineteenth-century paradigm for metal bridges;
the specifications called for open-hearth steel.
The Delair Bridge is most significant for its two movable spans, representing the state of the art in the late nineteenth and mid-twentieth centuries. The 1896 swing span has several innovative features, probably devised by C. C. Schneider, chief engineer of Pencoyd Iron Works' Bridge and Construction Department, who was known for his swing bridge designs. At midspan, two heavy floor beams deliver the truss's weight to the center bearing, an unprecedentedly large steel casting with a phosphor bronze bearing surface 27" in diameter.
The Delair Bridge's vertical-lift span represents more man six decades of development in that type. A vertical-lift bridge is defined by a truss raised and lowered between two towers, balanced by counterweights falling and rising at either end. The U.S. had but one long-span vertical-lift bridge in 1896, at South Halsted Street in Chicago, designed by J. A. L. Waddeill. Because of the prototype's expensive construction and questionable reliability, it was not immediately popular. John L. Harrington, Waddell's partner from 1907 to 1913, seems to have been responsible for developing the vertical-lift bridge into a practicable design. Railroads subsequently embraced the design for long-span movable bridges. When, in the 1950s, the U.S. Army Corps of Engineers proposed widening and straightening the Delaware River channel to serve industry upstream, a vertical-lift span was PRR's only option for providing the necessary 500' clearance. The railroad turned to New York-based consulting engineers Hardesty & Hanover, one of several descendants of Waddell & Harrington's partnership. They designed a riveted Warden through truss, 542'-0" long between bearings, to replace the fixed truss west of the swing span. Winding machinery atop each of the towers would lift the span up to 135'-0" above the high-water mark.The Delair Bridge's vertical-lift span represents more man six decades of development in that type. A vertical-lift bridge is defined by a truss raised and lowered between two towers, balanced by counterweights falling and rising at either end. The U.S. had but one long-span vertical-lift bridge in 1896, at South Halsted Street in Chicago, designed by J. A. L. Waddell. Because of the prototype's expensive construction and questionable reliability, it was not immediately popular. John L. Harrington, Waddell's partner from 1907 to 1913, seems to have been responsible for developing the vertical-lift bridge into a practicable design.IS Railroads subsequently embraced the design for long-span movable bridges. When, in the 1950s, the U.S. Army Corps of Engineers proposed widening and straightening the Delaware Elver channel to serve industry upstream, a vertical-lift span was PRR's only option for providing the necessary SOO'-O" clearance. The railroad turned to New York-based consulting engineers Hardesty & Hanover, one of several descendants of Waddeil & Harrington's partnership. They designed a riveted Warden through truss, 542'-0" long between bearings* to replace the fixed truss west of the swing span. Winding machinery atop each of the towers would lift the span up to 135'-0" above the high-water mark. American ridge Co...erected the towers around the existing bridge with minimal interruptions to traffic. Meanwhile, another crew constructed the lift span on falsework atop a barge anchored off the Pennsylvania shore. The spans were swapped out, using the rising tide to lift the fixed span off the piers and the falling tide to lower the lift span into place. Once cables were connected to the operating machinery and counterweights, the new vertical-lift bridge was ready for operation. Crews then demolished Pier No. 2 to clear the channel. The bridge remains in active service today, carrying Atlantic City-bound passenger trains as well as freight.
[The above text is from HAER, pp2-5]
The SS Marie Leonhardt, an oceangoing ship carrying iron ore to the new Fairless Works steel facility in Morrisville, allided with the bridge at about 12:45pm on Jan. 9, 1959, when the operator did not open it in time. This is one of the few lawsuits concerning allisions that was won by the ship owners. The reason the ship won was because the railroad had signaled all clear, but when it then tried to open the span after a train had passed, it could not because it was rusted shut. [sjrail, philadelphia-reflections] Remember, the bridge has a 50' clearance so the span would seldom be opened. But this inaugural run of an iron ore ship for the new USS plant required the span to open.
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| sjrail |
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| 20151212 7488rc [DeBruler] |
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| Michael Froio Photography posted Delair Bridge, looking west across the 542’ lift span over the Delaware River’s ship channel. Over the years my personal work has led to opportunities to serve commercial clients. I’ll be presenting a lecture Monday, October 22nd in Haddon Heights, NJ about these projects and the logistics of documenting fast paced engineering projects on the railroad. For more information please check out the event link https://www.facebook.com/events/1894687810613435/?ti=ia |
(new window starting at railroad bridge) (source) You can mute the "music" with no loss of information and with a preservation of sanity.
