. Armour engineer. Jan. 1910] PENN: CONCRETE ARCH BRIDGE 103 For the falsework, short piles were driven in bents par-allel to the direction of the canal, an opening of 18 feet beingleft in the center of the canal. The piles could not be driven invery straight rows, so that 12 by 12 inch caps were placed onthem at the same elevation wherever possible. Upon this table,accurately spaced bents, parallel to the direction of the canal,were constructed. Upon these bents 2 by 12 inch stringerscut from patterns were placed, spaced 12 inches center to cen-ter. This gave the curve of the arch very accura
. Armour engineer. Jan. 1910] PENN: CONCRETE ARCH BRIDGE 103 For the falsework, short piles were driven in bents par-allel to the direction of the canal, an opening of 18 feet beingleft in the center of the canal. The piles could not be driven invery straight rows, so that 12 by 12 inch caps were placed onthem at the same elevation wherever possible. Upon this table,accurately spaced bents, parallel to the direction of the canal,were constructed. Upon these bents 2 by 12 inch stringerscut from patterns were placed, spaced 12 inches center to cen-ter. This gave the curve of the arch very accurately. Dressedand matched lumber placed upon this gave a very smoothsurface. The arrangement of the piles and bents is shown irPig. Fig. 4. Elevation of Hand Railing and Pedestals. Some fourteen tons of twisted bars are imbedded in thebridge. In the arch proper they are spaced 1 foot apart, oneabove the other, as is illustrated in Fig. 2. Splices are alter-nated by using various lengths for the rods. Three different kinds of concrete were specified. A 1:3 :5mixture was called for in the foundations up to the skewbacks. The arch proper, spandrel walls, sidewalks and curbsare built of a 1:2:4 mixture. The railing, cornice and orna-ments are made of a 1:2:3 mixture, using roofing gravel for
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Keywords: ., bookcentury1900, bookdecade1910, bookidarmourengine, bookyear1910
