. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools . partof the rule as |-f-(9lX95). In the first case the product ()could be read directly to the nearest .2 of a cubic yard, whichis imnecessarily accurate. In the other case, the product(8004) could only be obtained by estimating -^ of a division. The computation for the prismoidal correction (see § 114),may be made similarly except that the divisor is instead of 5 5X11 For example, ff-() =-^ - Set the 324 on scale B (also specially marked like 108) opposi
. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools . partof the rule as |-f-(9lX95). In the first case the product ()could be read directly to the nearest .2 of a cubic yard, whichis imnecessarily accurate. In the other case, the product(8004) could only be obtained by estimating -^ of a division. The computation for the prismoidal correction (see § 114),may be made similarly except that the divisor is instead of 5 5X11 For example, ff-() =-^ - Set the 324 on scale B (also specially marked like 108) opposite 55 on scale A,and proceed as before. 107. Approximate volume. Irregular sections. In cross-sectioning irregular sections, the distance from the center andthe elevation above grade ^ of every ^ break in the cross-section must be observed. The area of the irregular sectionmay be obtained by computing the area of the trapezoids {fivCfin Fig. 53) and subtracting the two external triangles. For the area would be \ §107, EARTHWORK, 125 hi + ki. , ki + d , d + jr , jr + JCr , ^ V _,kr + hr, .hi/ h\ hr[ h\. Fig. 53. Expanding this and collecting terms, of which many willcancel, we obtain Area 4[ xiki+yiid—hi) +Xrkr+yr(jr—hr) ■\-Zr(d-kr)-\ (hl + hr) ] (50), An examination of this formula will show a perfect regu-larity in its formation which will enable one to write out asimilar formula for any section, no matter how irregular or howmany points there are, without any of the preliminary formula may be expressed in words as follows: ^ Area equals one-half the sum of products obtained as follows: the distance to each slope-stake times the height above grade ofthe point next inside the slope-stake; the distance to each intermediate point in turn times the height ofthe point just inside minus the height of the point just outside; finally^ one-half the width of the roadbed times the sum of theslope-stake heights, 126 RAILROAD CONSTRUCTION. § 108. If one of the side
Size: 1954px × 1279px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookidrailr, bookpublisheretcetc
