Almost all states and territories in Australia require that land developers conduct a contour survey before the commencement of any development. A contour or topographic survey is a 2-D or 3-D map that shows the elevations of property together with all naturally occurring and artificial features such as drainage, vegetation, adjacent structures and utilities. Some of the attributes in a topographic survey include, but not limited to size, location, elevation and height. Here are some top facts for beginners to know about a feature survey in residential property:
Drawing Contours -- A surveyor will use survey equipment such as GPS units to calculate the surface level of the block illustrated by contour lines. Therefore, each line represents a particular height at an interval of at least 0.2 meters. If the lines are closely spaced, then that indicates that the block has a steep slope and vice-versa.
Temporary Benchmark (TBM) -- a brief benchmark is a fixed point that has a known elevation in contour surveying. A surveyor uses the benchmark point as a base to refer other locations. The reference is temporary as it is only used during this survey and not in later phases of development. Typically, the TBM is given a well-rounded figure such as 100.00m. However, this number does not represent the actual height above Sea Level. The only instance when the TBM matches the height above Sea Level is when the floor level of a proposed structure is above the Australian's 100-year flood level.
The accuracy of Measurement -- The accuracy of measurements in a topographic survey can influence subsequent works on the property. For example, measures should be considered accurate on boundaries instead of an offset of a few meters. Therefore, when purchasing sites that have already received approval from the local authority, it is prudent to conduct an independent contour survey to ascertain the correctness of the measurements. Any inaccuracies during the surveying process can interfere with the site preparations, and thus, cause delays in site development.
Contour Surveys Aid in Determining Construction Costs -- A contour survey will help an architect to determine the amount of site works needed, and hence, aid in putting a dollar value on the project. The contour measurements can help to calculate the volume of earth to be removed as well as the height of retaining walls to be built in case of a sloping site. Therefore, the builder can factor such calculations to come up with the cost of works before actual construction of a building starts.Share