. Railroad structures and estimates . each otherand bolted. A close floor of cedar spars, not less than 8 inches in diameter,is laid on the first tier of cross ties to hold the ballast, or stonefilling; sometimes the floor is laid solid crosswise of the crib andresting on bottom longitudinal face courses. APPROXIMATE COST OF CRIBBING IN PLACE. Squared timbers, per thousand feet board measure $30. 00 to $50. 00 Round cedar timbers, per foot 12 to .20 Iron in crib, per pound 04 to .06 Filling (stone or ballast), per cubic yard 25 to Leveling off and clearing (dry), per cubic yard 20 to .30
. Railroad structures and estimates . each otherand bolted. A close floor of cedar spars, not less than 8 inches in diameter,is laid on the first tier of cross ties to hold the ballast, or stonefilling; sometimes the floor is laid solid crosswise of the crib andresting on bottom longitudinal face courses. APPROXIMATE COST OF CRIBBING IN PLACE. Squared timbers, per thousand feet board measure $30. 00 to $50. 00 Round cedar timbers, per foot 12 to .20 Iron in crib, per pound 04 to .06 Filling (stone or ballast), per cubic yard 25 to Leveling off and clearing (dry), per cubic yard 20 to .30 Leveling off and clearing (wet) 50 to 1. 00 CRIB ABUTMENTS. 101 Crib Abutments. (Fig. 22.) — For permanent structures onhigh fill embankments timber crib abutments are sometimesplaced, when the cost of masonry to solid ground would beexcessive and out of proportion to the balance of the a number of years, when the bank is solidified, the cribmay be removed and a masonry abutment placed in the usualway. Base of Kail. These piles only at3 Fig. 22. APPROXIMATE COST OF ONE CRIB ABUTMENT. 5000 feet board measure timber at $30 $ 16 piles 30 feet long each = 480 feet at 20 cts 500 pounds iron in above at 5 cts Back filling, etc .^ Total .* $ The wooden abutments illustrated above are built of 12 in. by12 in. timbers dovetailed at the ends, with cross ties about 3 on the lower portion of the crib only. The floor or bridgeseat is made solid with 12 in. by 14 in. timbers. All timbers aredrift bolted with | in. round spikes. The piles are 10 to 12 at about 3 ft. centers. The crib after completion isfilled with stone or good coarse gravel baUast. 102 RAILWAY BRIDGES. RAILWAY BRIDGES. Deck Plate Girders. (Fig. 23.) — Deck plate bridges aremade of steel plates and angles, fabricated and riveted up intogirders, etc., in the shops. The girders are placed at 9 feet centers more or less, and areheld laterally by ste
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