BRIDGES AND
TUNNELS OF
ALLEGHENY COUNTY,
PENNSYLVANIA
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HAER
Smithfield Street Bridge, Pittsburgh, PA
01 Cover Page
02 Foreword
03 Ferries
05 Monongahela
Bridge and
Fire
12 Masonry
17 Removal
of Old and
Erection of
New Bridge
18 Flooring
19 Ornamental
Towers and
Painting
22 Alterations
23 Footnotes
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Smithfield Street Bridge, Pittsburgh, PA Historic American Engineering Record PA-2 page 19
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The Ornamental Towers The ornamental towers are built of cast-iron, the roofs being of wrought-iron; they support merely their own weight; they incase the steel posts, which, to the eye, would seem very slender supports, and would appear out of proportion in comparison with the heavy piers and high trusses. The end posts can rock inside of the towers, which are not in any way connected with them. Where the trusses pass through the towers, room is left for expansion from temperature changes. "The architecture of the towers is so planned, and the composing parts so arranged, that the portals may be widened out to suit the entrance to a wider bridge, should it be required.
Painting "Besides painting the metal with raw linseed oil at the mills, and iron oxide paint at the bridge shops, two coats of white lead paint were applied to the erected steel and iron work. The white lead paint was used without any dryer, and mixed with boiled linseed oil only. All joints and crevices where water might collect, were puttied all around and raw linseed oil poured in, as much as they would hold. "As the erection took place mostly in inclement weather, the shop paint came off in many places by dragging the pieces through slouch and mud, which, especially in Pittsburgh, rusts iron rapidly. "Rusty places were coated with a thin lime paste, which, after drying, was scrubbed off with wire brushes and freshly painted. "All iron work under the flooring has been painted brown, all iron and steel work above the flooring is blue. The towers have a stone color.
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Introduction Last modified on
30-Sep-99
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