Follow the jump to see more pictures.

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Want to find out why the eastern abutment of the uninspiring Chestnut Street Bridge looks like a cathedral? Check out my post at Phillyhistory.org here. Above is a pretty shoddy overlay of a 1958 HAER photo onto a relatively picture of the bridge taken last April when Penndot was doing a structural investigation of the bridge. Interestingly enough, concrete from of the “new” 1956-59 bridge was failing with chunks falling on the Schuylkill Banks path. The 1866 abutment seemed to be holding up.

[DEMOLITION OF KNEASS'S 1866 BRIDGE, 1957-58 FROM HABS]

One of the issues that I wanted to clarify in the Phillyhistory.org piece was that the Expressway and increased traffic both conspired against Kneass’s bridge and led to its demise. According to a Streets Department publication, Paving the Way from 1956-59, that while most of the bridge rehab projects “were directly connected with expressway construction”… “considerable emphasis was given to the replacement of existing spans unable to handle today’s traffic volumes. Structures like those on Chestnut St…..”

Follow the jump for photos of the Penndot bridge inspection and the offending concrete.

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Nature is slowly enveloping the various components of this switch and signal apparatus on the eastern approach of the Grays Ferry Swing Bridge. Portions of the electro-mechanical device alerted the bridge tender that a train was present and the bridge could not be moved. Conversely if the bridge was open, trackmen could throw this switch and bar trains from moving across the bridge.The now-defunct Bethlehem Steel did brisk business in railroad “safety” switches in the early part of the 20th century. US Switch and Signal was (and is) also a major producer of railroad gates and signals.

On the surface of these components are raised company names, trademarks and operating instuctions (”depress here to apply padlock”) — creating a strange island of legibility amid the underbrush. While we understand or can conjecture the function of some parts, with others we lack the lived experience to gather meaning. And so this old century’s bit of modernity is being swallowed up both physically and conceptually.

When the Schuylkill river was a conduit for coal, lumber, refined petroleum products, stone, and other finished goods, nearly every crossing south of the mound dam at Fairmount was of sufficient height to allow barge traffic. Some like the University Ave Bridge, the South Street Bridge, the CSX rail bridge (that carries our vaunted trash trains to us), and a tiny one track ex-PRR railroad swing bridge south of the Grays Ferry Bridge had mechanical appurtenances enabling them to open, swing, and elevate around river traffic.

The PRR swing bridge locked in the open position and the currently-used railroad bridge just south have the distinction of being the only two swing bridges in the city of Philadelphia. During the heyday of civil engineering, swing bridges were some of the most innovative — and trickiest — bridges to execute. Unlike a drawbridge or a bascule bridge, swing bridges were almost exclusively dependent on their central pivot point which is situated within the ship channel. Barges striking the central pier could damage either the central span or its pivot or bring the entire structure out of true with its approaches. The central pivot also had to be maintained, cleaned, and lubricated. New York City’s Third Avenue Swing Bridge, the only in that city, still requires consistent upkeep.

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What is a Northeaster? Why is it pronounced Na’hreastah like we’re in Amoskeag? Why are they the worst storms ever? Why aren’t they called ice hurricanes? Checking the index in my handy Audubon Society Field Guide to North American Weather it explains, laymanly:

“As a cold front enters the trough along the South Atlantic Coast and cold polar air passes over the warm waters of the Gulf of Mexico or Gulf Stream off Georgia and the Carolinas, storms can develop quickly. They move nahtheest along the coast, delivering driving stow in winter and cold rain in summer–the famous na’hreasteah of the Atlantic seaboard.”

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