Engineering and Contracting . hey arc used. 394 Engineering and Contracting Vol. XLI. No. 13. Drilling Outfit.—Steam drills are used withhard rock, while a large percentage of theother holes are put down by hand and churndrills. In many places churn drills were suc-cessful in soft rock. In all hard rock, steamdrills are used when possible. The two drillsused were the Ingersoll P-24 type with 6^-in. stroke. One 12 HP. boilersupplied the two drills. Cost of Excavating a Rock Sidehill Cut.—Several large blasts have been successfullymade along the route in sidehill cuts on diflfer-
Engineering and Contracting . hey arc used. 394 Engineering and Contracting Vol. XLI. No. 13. Drilling Outfit.—Steam drills are used withhard rock, while a large percentage of theother holes are put down by hand and churndrills. In many places churn drills were suc-cessful in soft rock. In all hard rock, steamdrills are used when possible. The two drillsused were the Ingersoll P-24 type with 6^-in. stroke. One 12 HP. boilersupplied the two drills. Cost of Excavating a Rock Sidehill Cut.—Several large blasts have been successfullymade along the route in sidehill cuts on diflfer- Percu. yd. 121 cans power at $ $ $0,121 150 lbs. dynamite at $ 50 20-ft. fuses 58 16-ft. fuses Labor drilling; .^tld loading , 81 men at $ Total $ $0,343 About 320 ft. of holes were drilled at acost of 40 cts. per lineal footfor drilling labor, which was only ft. ofhole per cubic yard of rock blasted. Powder. 5eC+ton A-B •Crib shown thus to beused only when Bent isin Water ? ^ ?. ^ <d-i y M / m m - JL Section CD Fig. 10. Details of Timber Pier for 28-Ft. Trestle Spans Over Elk Creek, W. & Y. V. R. R. ent sections of the line, moving almost Yz of material for every pound of powderused. In one cut, estimated at 8,000 cu. per cent of which was solid rock, 33 holeswere driven in two rows, the upper row 20 ft. deep and extending 2 grade, while the lower holes were 16ft. deep, extending 6 ft. below grade. Theholes were expanded or sprung twice, firstby using 5 or 6 sticks of dynamite and thenby using 25 or 30 sticks. This material wasall rock and the second expansion of theholes was necessary, although it is believedthat one expansion of the holes, using 10 or 12 sticks of dynamite, would have given bet-ter results, as the second expansion tended tofill the holes rather than open them up to suffi-cient size. An averag
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