Surveying

Surveying is the art and science of accurately determining the position of points and the distances between them. These points are usually, but not exclusively, associated with positions on the surface of the Earth, and are often used to establish land boundaries for ownership or governmental purposes.

Types of surveys

• ALTA/ACSM survey: A surveying standard jointly proposed by the American Land Title Association and the American Congress on Surveying and Mapping that incorporates elements of the boundary survey, mortgage survey, and topographic survey. ALTA/ACSM surveys, frequently shortened to ALTA surveys, are often required for commercial real estate transactions.
• Boundary survey: The actual positions of existing marks on land (typically iron rods or concrete monuments in the ground, but also tacks in trees, pipes, and manholes) are measured, and a map is drawn from the data.
• Deformation survey: a survey to determine if a structure or object is changing shape or moving . The three-dimensional positions of specific points on an object are determined, a period of time is allowed to pass, these positions are then re-measured and calculated, and a comparison between the two sets of positions is made.
• Draw lot: One lot from a plat is drawn, with any easements and setbacks that may be on it.
• Foundation survey: The position of the house is measured before it is finished being built.
• Mortgage survey: A simple survey that generally determines land boundaries and building locations. Mortgage surveys are required by title companies and lending institutions when they provide financing to show that there are no structures encroaching on the property and that the position of structures is generally within zoning and building code requirements. Mortgage surveys are not sufficiently accurate for use in building new structures.
• Physical survey: The finished house and driveway are measured, and all markers on the boundary are indicated. This is recorded when the lot is sold.
• Plot plan: A proposal for a house or other building and driveway or parking lot are added to a draw lot.
• Subdivision plat: A plot or map based on a survey of a parcel of land, lines are drawn inside it, indicating where roads and lots are. Plats are usually discussed back and forth between the developer and the surveyor until they are agreed on, at which point pins are driven into the ground to mark the lot corners and curve ends and the plat is recorded in the cadastre (USA, elsewhere) or land registry (UK).
• Topographic survey: A survey that measures the elevation of points on a particular piece on land, and presents them as contours on a plot
• Construction surveying (otherwise 'lay-out' or 'setting-out'): The process of establishing and marking the position and detailed layout of new structures such as roads or buldings for subsequent construction. In this sense, surveying may be regarded as a sub-discipline of civil engineering.