. Railroad structures and estimates . 0 100 1150 48 Pile foundation extra. Masonry foundation and fastenings not included. Ballasted Floors. — Where on account of difficulty of obtaininga good foundation or procuring material for a permanent struc-ture except at a prohibitive cost, the use of wooden trestle bridgewith ballasted floors is sometimes the best alternative betweenthe costly permanent structure or the common wooden trestlewith open deck. There are two types of floor construction for ballast floorwooden trestles in general use, one having the string
. Railroad structures and estimates . 0 100 1150 48 Pile foundation extra. Masonry foundation and fastenings not included. Ballasted Floors. — Where on account of difficulty of obtaininga good foundation or procuring material for a permanent struc-ture except at a prohibitive cost, the use of wooden trestle bridgewith ballasted floors is sometimes the best alternative betweenthe costly permanent structure or the common wooden trestlewith open deck. There are two types of floor construction for ballast floorwooden trestles in general use, one having the stringers placed soas to form a solid floor, Fig. 34, and the other having the stringersseparated and covered with plank, Figs. 35 and 36. Usually all the timbers in the construction of the ballast floorare treated by creosote or other process. The estimated life of these bridges varies from twenty totwenty-five years when treated, without repairs of any con-sequence. 130 BAXLAST FLOOR FOR TRESTLES. 5^ J* X ffi Bolts ^V X 22 Drift Bolts^. Bents U C. to C. I \ Fig. 34. BaUasted Floor Trestle, H. T. & S. Fe. Ry. -110- -7 0- %x 29Bolt-1^Cast Iron Separator-t| 7 X IC Stringers : ; 10 Per Pane-f. 6 X S s S 0 Tie , -7 0- TlQj H-Cx8x 280 Guard Raa v^-+2 6-^
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Keywords: ., bookauthororrockjohnwilson1870, bookcentury1900, bookdecade1910
