. Railroad construction. Theory and practice. A textbook for the use of students in colleges and technical schools. By Walter Loring Webb . Fig. 60. possible sliding on each other. Spreading in layers has theadvantage of partially ramming each layer, so that the subse-quent shrinkage is very small. Sometimes small trendies aredug along the lines of the toes of the embankment. This willfrequently prevent the sliding of a large mass of the embank-ment, which will then require extensive and costly repairs, tosay nothing of possible accidents if the sliding occurs after theroad is in operation. In
. Railroad construction. Theory and practice. A textbook for the use of students in colleges and technical schools. By Walter Loring Webb . Fig. 60. possible sliding on each other. Spreading in layers has theadvantage of partially ramming each layer, so that the subse-quent shrinkage is very small. Sometimes small trendies aredug along the lines of the toes of the embankment. This willfrequently prevent the sliding of a large mass of the embank-ment, which will then require extensive and costly repairs, tosay nothing of possible accidents if the sliding occurs after theroad is in operation. Incidentally these trenches will be ofvalue in draining the subsoil. AVhen circumstances require anembankment on a hillside, it is advisable to cut out steps toprevent a possible sliding of the whole embankment. Merely 116 RAILROAD CONSTRUCTION. § 99. ploughing the side-hill will often be a cheajDer and sufficientlyeffective Fig. 61. Occasionally the formation of a very high and lono- embank-ment may be most easily and cheaply accomplished by buildinga trestle to grade and opening the road. Earth can then beprocured where most convenient, perhaps several miles away,loaded on cars with a steam-shovel, hauled by the trainload, anddumped from the cars with a patent unloader. On such a largescale, the cost per yard would be very much less than by ordi-nary methods—enough less sometimes to more than pay for thetemporary trestle, besides allowing the road to be opened fortraffic very much earlier, which is often a matter of primefinancial importance. It may also obviate the necessity forextensive borrow-pits in the immediate neighborhood of theheavy fill and also utilize material which would otherwise bewasted. COMPUTATION OF HAUL. 99. Nature of subject. As will be shown later when analyz-ing the cost of earthwork, the most variable item of cost is thatdepending on the distance hauled. As it is manifestly imp
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