. The railroad engineer's practice . 14rfeet span. Frames 2ifeet J-ThicK 24:-feet span, 8-feet rise. Frames 3^/eef apart. Post mortised (by slight tenon) into chord. Arch piecespinned together and halved in chord and post; bracesspiked at ends; and at intersection with post a ^-inch boltis used. Centres should be removed from arches, unless laid in avery quick-setting mortar, within a few days after theircompletion. In stone arches the parapet should not bemade too high, or it may be pushed over by the bank ;it is well to proportion it like a retaining waU if more than 44 one or two co
. The railroad engineer's practice . 14rfeet span. Frames 2ifeet J-ThicK 24:-feet span, 8-feet rise. Frames 3^/eef apart. Post mortised (by slight tenon) into chord. Arch piecespinned together and halved in chord and post; bracesspiked at ends; and at intersection with post a ^-inch boltis used. Centres should be removed from arches, unless laid in avery quick-setting mortar, within a few days after theircompletion. In stone arches the parapet should not bemade too high, or it may be pushed over by the bank ;it is well to proportion it like a retaining waU if more than 44 one or two courses hisrh. Some loose stones laid flat-wise behind it will relieve the thrust of the earth. In designing centres, allow ^^^ of the span for settlingof the arch, unless built very slowly and with great care. RETAIXIXG WALLS. Lst b = the breadth at the bottom = = the height. t = the thickness at the = tlie weight of a unit of volume of — the weight of a unit of volume of = the slope of the bank above the wall.(p = the angle of repose o
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Keywords: ., bo, bookcentury1800, bookdecade1880, bookidrailroadengineer00clee
