Plane & Geodetic Surveying In Civil Engineering

Surveying can be geodetic or a plane survey.

So what’s the difference between geodetic surveying and plane surveying?

Plane Surveying

In plane surveying, the area under consideration is taken to be:

horizontal plane, and the measurements plotted will represent the projection on the horizontal plane of the actual field measurements. 

A horizontal plane is one, which is normal to the direction of gravity, as defined by a plumb line at a point.

Geodetic Surveying

This is the type of surveying which the earth’s curvature is taken into account.

Due to this curvature of the earth, a horizontal plane will be tangential to the earth’s surface at each point it is defined. 

As an effect, if a large area is considered on this basis, the discrepancy will become apparent between the area of the horizontal plane and the actual curved area of the earth’s surface 

It can be shown as presented by (Bennister and Raymond; 1977) that for surveys up to 250km2 in area, the discrepancy is not serious therefore, plane surveying will be adequate for all but the very largest scale surveys.

All surveys of countries, such as the Federal surveys of Nigeria are geodetic surveys.

The most refined instruments and methods of observations are made use of in geodetic surveying and the operations are directed to the determination of the positions on the earth’s surface of a system of points which serve as controls for all other surveys.

This may include surveys like cadastral, photogrammetry, hydrographic, topographic, mining and engineering.