. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . nce 20 ffletefs = feet, a 20-meter chord betweenthose same radial lines would subtend an arc with a radius fefet, or feet. But this radius, measuredin meters, would be (.)^ meters,which k In other words, the radius of any metriccurve, measured in meters, is numerically one-fifth of the radius,measured in feet, of the same degree curve, but in actua
. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . nce 20 ffletefs = feet, a 20-meter chord betweenthose same radial lines would subtend an arc with a radius fefet, or feet. But this radius, measuredin meters, would be (.)^ meters,which k In other words, the radius of any metriccurve, measured in meters, is numerically one-fifth of the radius,measured in feet, of the same degree curve, but in actual lengthis a little less than two-thirds. This practically means that a10° curve, nietric, is actually very much sharper than a 10®curve, using foot-measure, or that the radius is about 66% asmuch. Therefore, in selecting curves for location, an engineer,who is accustomed to the foot-measure system, should rememberthat a 10° curve metric, for example, has approximately thesame radius as a 15° curve, using foot-measure. While it ismore convenient for an engineer, who is constantly using themetric system for curves, to have tables computed directly on §48. ALINEMENT. 57. Fig. 12. this basis, an engineer need not be dependent on such tables,since it is only necessary to divide the tabular quantities in thefoot-table by 5 to obtain the correspond-ing quantities for the metric system. Thisapplies not only to radii, but also totangents, external distances and longchords for a 1 ° curve. A desired logarithmmay be obtained by subtracting the foot-table logarithm. For example, anticipating the explana-tion in Art. 53, what is the tangentdistance of a 6° metric curve, when thecentral angle is 32° 40. From Table II, wefind that by the foot-system the tangentdistance for a 1° curve when the centralangle is 32° 40 is feet; then fora 6° curve it is ^6= feet;for a 6° metric curve it is = meters. The radius of the 6° metric curve —
Size: 1095px × 2282px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorwebbwalt, bookcentury1900, bookdecade1920, bookyear1922
