vertical scale; that is, with the vertical scale perhaps10 times the horizontal scale. After the POVCs havebeen plotted, you should be able to draw a smoothparabolic curve through the points with the help of aship’s curve or some other type of irregular curve; ifyou can’t, check your computations.USING A PROFILE WORK SHEETAfter you have had some experience computingcurves using a table as shown in the foregoingexamples, you may wish to eliminate the table andwrite your computations directly on a working printof the profile. The engineer will set the grades andindicate the length of the vertical curves. You maythen scale the PVI elevations and compute the gradesif the engineer has not done so. Then, using acalculator, compute the POVT elevations at theselected stations. You can store the computations insome calculators. That allows you access to thegrades, the stations, and the elevations stored in thecalculator from one end of the profile to the other. Youcan then check the calculator at each previously setPVI elevation. Write the tangent elevation at eachstation on the work sheet. Then compute each verticaloffset: mentally note the x/ 1 ratio; then square it andmultiply by e on your calculator. Write the offset onthe work print opposite the tangent elevation. Next,add or subtract the offsets from the tangent elevations(either mentally or on the calculator) to get the curveelevations; then record them on the work sheet. Plotthe POVC elevations and draw in the curve. Last, putthe necessary information on the original tracing. Theinformation generally shown includes grades;finished elevations; length of curve; location of PVC,PVI, PVT, and the e. Figure 11-21shows a portion ofa typical work sheet completed up to the point ofdrawing the curve.FIELD STAKEOUT OFVERTICAL CURVESThe stakeout of a vertical curve consists basicallyof marking the finished elevations in the field to guidethe construction personnel. The method of setting agrade stake is the same whether it is on a tangent or ona curve, so a vertical curve introduces no specialproblem. As indicated before, stakes are sometimesset closer together on a curve than on a tangent. Butthat will usually have been foreseen, and the plans willshow the finished grade elevations at the requiredstations. If, however, the field conditions do require astake at an odd plus on a curve, you may compute theneeded POVC elevation in the field usinggiven on the plans and the computationalexplained in this chapter.the datamethodsFigure 11-21.—Profile work sheet.11-20

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