CULVERTS.

94. The length of any structure passing under a railroad embankment is L – 2Rh, where L is the distance between slope stakes, R inclination of slopes, h the height of structure from the natural surface. Thus, suppose the distance between slope stakes to be 100 feet, slope 1½ to 1, and h 10 feet, we have

L = 100 – (10 × 1½ × 2) = 100 – 30 = 70 feet.

The length of an oblique structure will of course be greater than that of one at right angles to the road; the length depending upon the obliquity.