Read the number opposite the pointer. That number is your true elevation. If using an optical instrument, just read the number across the horizontal line. That number is your true elevation.

How do you calculate grade elevations?

How to Find Grade of an Elevation. Grade can be found by measuring the horizontal length of an elevation, the run, and the vertical height of the elevation, the rise. Grade is expressed as rise/run, so if the rise is 25 and the run is 80 the grade is 25/80.

What elevations are indicated by benchmarks?

A benchmark is a point where exact elevation is known and is marked with a brass or aluminum plate. It is marked BM on the map with the elevation numbers given in feet. Benchmarks are useful to help determine contour lines.