. Building and repairing railways . Fig. 68. VENTILATION OF MT. CENIS TUNNEL. neer must keep in mind; he must never lose anopportunity to get a dry road bed; all cuts should,therefore, be made with a grade through them;the character of the material through which a cutis made must carefully be examined, for if a waterbearing strata of clay or gravel exists, prompt meas- CONSTRUCTION. 121 ures must be taken to prevent slides. This is donesometimes by making trenches up the slope atintervals through the cut and tilling these trenches. Figs. 69 and 70. RETAINING WALLS. with small stone leading to
. Building and repairing railways . Fig. 68. VENTILATION OF MT. CENIS TUNNEL. neer must keep in mind; he must never lose anopportunity to get a dry road bed; all cuts should,therefore, be made with a grade through them;the character of the material through which a cutis made must carefully be examined, for if a waterbearing strata of clay or gravel exists, prompt meas- CONSTRUCTION. 121 ures must be taken to prevent slides. This is donesometimes by making trenches up the slope atintervals through the cut and tilling these trenches. Figs. 69 and 70. RETAINING WALLS. with small stone leading to the side ditches, or,better still, by putting in an under drain. Ditcheswell back from the slope must be made to carry 122 BUILDING AND REPAIRING RAILWAYS. off the surface water to the end of the cut, andnot allow it to pass down the slope into the must be connected by ditches to givedrainage to openings, and, where there are no bor-rowpits, ditches must be made to protect embank-ments from being washed by water coming downslopes. Where ditching is resorted to, to reduce
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectrailroa, bookyear1901
