. Railroad construction. Theory and practice. A textbook for the use of students in colleges and technical schools. By Walter Loring Webb . termination of a generalroute along which it will be possible to survey a line whosemaximum orrade shall not exceed the rulinir s-rade. 5. Mountain route. The streams of a mountainous ree:ionfrequently have a slope exceeding the desired ruling grade. Insuch cases there is no possibility of securing the desired gradeby following the streams. The penetration of such a regionmay only be accomplished by development—accompaniedperhaps by tunneling. Development
. Railroad construction. Theory and practice. A textbook for the use of students in colleges and technical schools. By Walter Loring Webb . termination of a generalroute along which it will be possible to survey a line whosemaximum orrade shall not exceed the rulinir s-rade. 5. Mountain route. The streams of a mountainous ree:ionfrequently have a slope exceeding the desired ruling grade. Insuch cases there is no possibility of securing the desired gradeby following the streams. The penetration of such a regionmay only be accomplished by development—accompaniedperhaps by tunneling. Development consists in deliber-ately increasing the length of the road between two extremesof elevation so that the rate of grade shall be as low as desired. SAILBOAD CONSTBTICTION. §5. The usual method of accomphshing this is to take advantage ofsome convenient formation of the ground to introduce somelateral deviation. The methods may be somewhat classified asfollows: (a) Running the line up a convenient lateral valley, turninga sharp curve and working back up the opposite slope. Asshown in Fig. 1, the considerable rise between ^ and ^ was. Fig. 1. surmounted by starting off in a very different direction fromthe general direction of the road; then, when about one-half ofthe desired rise had been obtained, the line crossed the valleyand continued the climb along the opposite slope, (b) Switch-hack. On the steep side-hill BCD (Fig. 1) a very considerablegain in elevation was accomplished by the switchback gain in elevation from B \o D \& very great. On theother hand, the speed must always be slow; there are two com-plete stoppages of the train for each run; all trains must runbackward from C to D. (c) Bridge spiral. When a valley isso narrow at some point that a bridge or viaduct of reasonablelength can span the valley at a considerable elevation above thebottom of the valley, a bridge spiral may be desirable. In 6. RAILROAD SURVEYS. b Fig. 2 tlie line ascends tlic stream valley
Size: 1610px × 1552px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1900, bookdecade1900, bookpublishernewyorkjwiley
