Transcription: To create a road at a grade, say a 10% grade, we need to know the length of the run on the road. For a 10% grade, for every 50 meters of run, the road rises 5 meters and the toe of the fill line extends outward an additional 10 meters. Thus the constant elevation contours appear as lines which extend from the road at an angle of arc tangent outward extension over run, or in this case, arc tangent of 10 over 50 for the fill. We are using the same cut and fill ratios as for a level road.
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