. Railroad structures and estimates . n on each other and 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 $ to $ 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 1. 50 Leveling off and clearing (dry) per cubic yard . 20
. Railroad structures and estimates . n on each other and 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 $ to $ 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 1. 50 Leveling off and clearing (dry) per cubic yard . 20 to .30 Leveling off and clearing (wet) . 50 to 1. 00 CRIBS. 83 Crib Abutments. (Fig. 40a.) — 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. Fig. 40a. These piles only at 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 25. 00 Back filling, etc Total $ 84 RAILROAD STRUCTURES AND ESTIMATES. Tunnels. Any tunnel work will usually require a special survey and care-ful investigation before being undertaken. They are generally built straight, and are usually dug fromeach end. The construction depends on the nature of the material; invery soft ground a circular cross section is used or an invertedarch along the bottom with tapering sides and a semi-circle alongthe top. The general construction is usually a rectangle with a semi-circle or semi-ellipse top, lined on the inside and graded through-out its length so as to drain with open gutters on the sides. When wood lining is used it is made extra wide so as to allowfora permanent lining at a future d
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