Introduction
A Topographic Survey is a survey that gathers data about the elevation of points on a piece of land and presents them as contour lines on a plot. The purpose of a topographic survey is to collect survey data about the natural and man-made features of the land, as well as its elevations. Topographic maps are used to show elevations and grading features for architects, engineers, and building contractors.
The purpose is to gather spatial information relating to the site (natural and man-made land features). It is typically accepted that points are positioned in three dimensions which facilitates ground modelling and visualisations to be produced from the topographical survey.
Additional information can often be integrated into topographical surveys which assists a design team in taking account of the necessary and relevant site constraints. This can include site sections through particularly diverse gradient transects, spot heights of surrounding land and site features, i.e. neighbouring properties to assess overlooking, underground utilities information (from radar tracing and integrating utility records data).
One of the major purposes to conduct a topographic survey is to accumulate survey information about the natural and man-made characteristics of the land and its elevations. From this set of information the topographic land surveyors make three - dimensional maps. They prepare a topographic map after collecting the field data. To accomplish their topographic survey objectives, surveyors use elements of geometry, engineering, trigonometry, mathematics, physics and law.
The work involved in a topographic survey mainly consists of the following steps:
- Establishing horizontal and vertical control that will serve as the framework of the survey.
- Identifying horizontal location and elevation of ground points to provide enough data for plotting when the map is prepared
- Locating natural and man-made features that may be required by the purpose of the survey
- Computing distances, angles, volumes and elevations of earthwork.
- Finally, drawing the topographic maps.