What is the difference between reduced level & benchmark

Dnyan Deshmukh

Staff member
Reduced level also know as RL is the value or the elevation of the point from mean sea level (MSL).

You can measure the RL of any point on ground when you know the height of instrument of your level machine which is calculated by taking back sight on known value or elevation of point.

The point whose elevation or value is know is called as benchmark, benchmark can be temporary, permanent whose value can be either arbitrary or taken from mean sea level.

In most of the cases or almost everywhere, Benchmark has arbitrary values which are set to ensure all elevations or heights of the structures are built according to that benchmark value.

So to record RL you need to have benchmark and level machine.