. 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 . Fig. 26. radius. If the radius is not to be changed, the point of curv«must be altered as follows; b. To move the forward tangent parallel to itself a distance x,the radius being unchanged. (Fig. 26.) In this cas/e the whole §64. i^LINEMENT. 73 i curve is moved bodily a distance 00=^A = FF==J5j8, andmoved parallel to the first tangent AV Bn__sin nBB BB X sin A -AA (15) c. To change the direction of the forward tangen
. 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 . Fig. 26. radius. If the radius is not to be changed, the point of curv«must be altered as follows; b. To move the forward tangent parallel to itself a distance x,the radius being unchanged. (Fig. 26.) In this cas/e the whole §64. i^LINEMENT. 73 i curve is moved bodily a distance 00=^A = FF==J5j8, andmoved parallel to the first tangent AV Bn__sin nBB BB X sin A -AA (15) c. To change the direction of the forward tangent at the pointof tangency. (Fig- 27.) This problem involves a change (a) in the central angle and also requires anew radius. An error in the deter-mination of the central angle fur-nishes an occasion for its use. R, A, a, A V, and BV are ^ Bs==R vers A. R^R- ■a, Bs^Rvers A vers (J—a)As =R sin A. As =R sin A. (16^ AA=As—As=R sin A^R sin A, (17) The above solutions are given to illustrate a large class ofproblems which are constantly arising. All of the ordinaryproblems can be solved by the application of elementary geome-try and trigonometry. 64. Limitations in location. It may be required to run acurve that shall join two given tangents and also pass through agiven point The point (P, ) is assumed to be deter-mined by its distance (VP)from the vertex and by theangle AVP^/^. It is required to determinethe radius (R) and the tangentdistance (AV). A is known. PF(? = K180°-i)-/?=90°-(Ji+^/?).PP=2FP sin PFG =2FPcos(ii+/?).PSV^^A.
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Keywords: ., bookauthorwebbwalt, bookcentury1900, bookdecade1920, bookyear1922
