Land surveying is one of the world's oldest professions and dates back as far as the ancient Egyptians. In today's guide we shall look at land survey techniques, and how they are used.
History of Land Survey Techniques
As we mentioned in our introduction, land surveying dates back thousands of years and is an integral part of every major civilization. Ever since the beginning of man, civilizations have had the need to know what property is theirs and understands the shape of the land.
The basics fundamentals of land surveying have not changed since it first began, however the land survey equipment has changed drastically over the years.
In the past, land survey techniques had the right principles, however due to less knowledge and technology they weren't overly accurate or reliable. Modern land survey techniques are incredibly precise largely due to advanced technology available to create the tools used to perform the land survey techniques.
Essentially land survey techniques have remained very much the same - using fundamentals of mathematics including geometry, calculus and trigonometry. It is the tools that have changed.
Purpose of Different Land Survey Techniques
Land surveying is a very broad subject area and as such not every land survey technique is suitable for every application.
The type of land survey technique they choose to use will depend on a variety of factors. Largely it depends on the type of survey that they are doing. Land surveys can be divided into three basic categories: standard land surveys (fixing property lines, calculate land areas etc.); engineering surveys (ensuring building is constructed in correct place); and informational surveys that are used to create maps and charts.
Land surveys can also be classified as either geodetic surveys or plane surveys. Geodetic surveys are very precise and cover large areas.These require the curvature of the earth to be taken into consideration and require additional land survey techniques such as triangulation, trilateration and astronomical direction fixing.
Plane surveys differ in that they consider the surface of the Earth to be a flat plane, and curvature is not taken into consideration. Techniques for plane surveys include plane trigonometry and plane geometry. These types of land survey techniques are only used in small areas.
Additional sub categories of land surveys that will affect the chosen land survey techniques include: route surveys, property surveys, industrial surveys and hydrographic surveys.
Land Survey Techniques
There are numerous land survey techniques that are used in the various situations that we mentioned above, however there are five fundamental techniques that are used most commonly among land surveyors: triangulation, trilateration, traverse, leveling and radiation.
Triangulation land survey technique uses series' of connected triangles that join and overlap each other, and from there angles can be measured from determined stations. This is the most commonly used land survey technique and is also very efficient as it minimizes the number of measurements that need to be made.
Trilateration is a land survey technique that uses electronic distance measuring equipment to measure the lengths and sides of the triangles used in triangulation and from there the angles can be calculated. Trilateration is a preferred land survey technique in rough terrain where it can be easier to get accurate calculations than by using the traditional triangulation land survey technique.
Traverse land survey technique uses a series of lines whose distances and lengths have been measured and are connected together by points in determined locations. Traverse lines can be either open or closed and can be adjusted to go around rough terrain or obstacles as required. This land survey technique is commonly used for creating preliminary surveys for the building of new roads.
Leveling is a land survey technique that is used to determine the difference in elevation in a specified area by measuring vertical distances on a graduated rod using a leveling instrument. There are a variety of leveling instruments, however dumpy levels, transits and Theodolites are the preferred option. Using trigonometry the difference in elevation between two points can be established.
The final land survey technique is Radiation. Radiation is a land survey technique that is used most commonly in conjunction with a plane table. Using a fixed position above a ground location various points are taken at the boundary of the survey area. These points are drawn on a piece of paper and the distances measured and converted to the required scale on the survey sheet. Radiation is commonly used with other land survey techniques such as traverse and triangulation.