Topographic Land Survey
The land survey that most people are familiar with, a survey to set the boundaries of a piece of real estate, is actually just one of many different types of land surveys. A topographic land survey may be used for homeowners or those in the construction industry or environmental sector. The point of a topographic land survey is to note the natural and manmade features within the land. These may include hills, ravines, streams, trees, fences, buildings, and other improvements over the natural state of the land. A topographical survey shows the location, size, and height of these types of improvements, as well as gradual changes in elevation. Topographic surveys are sometimes called contour surveys, and may be conducted before the land changes hands, or as the landowner is preparing to improve the land.
Unlike boundary or residential land surveys, a topographic land survey focuses more on elevation than on horizontal measurements. Most measurements are done either with a surveying-quality GPS unit, or with an electronic EDM instrument. The results of the topographic survey are not marked using stakes or other landmarks, like with most other land surveys. Instead, they are presented as contour lines on a map of the land. Today, sophisticated computer programs allow for digital versions of these maps, as well as interactive elevation views of the land. The data may be used in Cad programs (such as Terramodel, Microstation, AutoCad), where it can be manipulated by engineers or architects to show how the topography will change through the planned improvements.
Topographic land surveys have many uses. In some cases, they may be required by the government. Engineers and architects use such surveys to design buildings or other improvements to be situated on the property, as existing features may influence their design or decisions on where to site the structure within the property. All construction projects begin with such a topographic land survey, which describes the starting point of the land before improvements are made.
Topographic surveys may also be used when determining the optimal plan for drainage ditches, grading, or other features, using the natural landscape as the basis for such improvements. The survey will also record any slopes on the land, which is particularly important if you’re considering building on the land, as an 8 degree slope is near the limit for economically building on a hillside; steeper slopes are generally not economically feasible for building purposes due to increased costs for foundations and other requirements. Having a topographic survey conducted prior to purchasing the land can ensure that the land’s features will be suitable for its intended use.
Besides undeveloped land or land with structures, topographic land surveys are also useful when the area has been previously used, but is now being redeveloped. For example, topographic surveys may be conducted of land after a previous building is demolished, or of a quarry, landfill, or other area with changing topographic data. In these cases, a topographic survey provides an accurate view of how the land has been changed by its use, allowing for better planning for future use.
Charles Lee Iner, RLS
June 2009