Field note / site geometry
Rise and fall need a sign convention.
With a chosen direction of travel, a positive vertical change represents a rise and a negative change represents a fall. The horizontal run is not the same as the sloping distance along the finished surface.
Three common descriptions.
Grade percentage is vertical change divided by horizontal run multiplied by 100. The angle is the inverse tangent of the same ratio. A ratio such as 1 in 20 means one unit of vertical change for 20 units of horizontal run; for a fall, keep the direction explicit.
What the quick conversion cannot prove
- Compliance with accessibility, vehicle, road, rail, drainage, crossfall, or maintenance standards.
- Earthwork stability, erosion, settlement, compaction, tolerances, or constructability.
- That a surveyed chainage, plan distance, or level difference matches the simple two-point geometry.