Topographic Surveys are used to identify and map the contours of the ground and existing features on the surface of the earth or slightly above or below the earth’s surface (i.e. trees, buildings, streets, walkways, manholes, utility poles, retaining walls, etc. These are more commonly referred to as topo surveys.
Topo surveys are commonly used by engineers and architects to base the design of their projects, for this reason they are usually done in the preliminary stages of a new project. Conversely, asbuilt (or as-constructed) surveys are typically done at the end of a project to ensure the project was built according to design.