The Basics of Surveying

Surveying is an essential process for identifying and mapping the position of terrain. It helps with everything from determining land boundaries to ensuring that buildings are constructed according to plan. It is an ancient practice. However, the modern tools and survey equipment available today offer levels of precision that have never before been possible.

Defining Surveying

Infographics the basics of surveying

Surveying is the process of measuring the relative positions of objects near the earth’s surface. It involves making distance and angular measurements. Surveyors use these measurements to calculate the position of objects in three-dimensional space relative to a known point. In addition to using survey instruments, surveyors must be skilled at mathematical calculations. Additionally, surveying often involves constructing maps, cross-sections, diagrams and profiles to record the relevant data.

Why Surveying Is Important

Without surveying, major engineering projects would not be possible. Railways, highways, canals, skyscrapers, bridges and more all rely on surveying to ensure accuracy and efficiency. Although small structures can be built without surveying, large buildings would be nearly impossible without it. Imagine two people trying to make a mile-long road together, each one starts a different endpoint of the road. If they build towards each other, it would be almost impossible to properly link up in the middle without surveying. Any structure that is built on the land requires good surveying to ensure accuracy.

Types and Methods of Surveying

Surveying can be classified in a few ways. There are two types of surveying and several methods. Surveys can also be classified by the type of instruments used.

Types of Surveying

Geodetic surveying is the type that treats the earth as a sphere. This is more complex but typically only necessary for large areas. It is more common with projects to gather accurate geographical and topographical information for a large area. Most construction projects do not require this. Plane surveying is a simpler type that treats the surface of the earth as a flat surface. The curvature of the earth is so slight that only the largest projects require geodetic surveying. In many cases, it is simpler and nearly as accurate to neglect the spheroid shape.

Classification Based on Method/Nature of the Survey

Surveying can also be categorized based on the method used. These are some of the common methods of surveying:

Astronomical involves mapping sections of the sky using telescopes.
Boundary is used to find, measure and mark the boundaries of sections of land (typically for ownership purposes).
Construction is used to correctly layout key points of a construction or engineering project.
Control is used to find the correct positioning is an arbitrary point.
Hydrographic is surveying used for bodies of water to aid navigation, underwater construction and water supply management.
Mining is land surveying used to locate and map underground and surface features for mining operations.
Photogrammetric utilizes aerial photography to rapidly and accurately determine the position of objects.
Route provides controls and data necessary for constructing transportation routes such as railroads, highways and canals.
Topographic measures the position and configuration of terrain to create topographical maps.

Classification Based on the Survey Instruments

There are a number of pieces of equipment used by surveyors. Many techniques are derived from using certain instruments. In many cases, two or more instruments will be used in conjunction.

Chain: A chain is one of the oldest and simplest methods of making measurements. Distances can be measured using the chain’s length. Angles can either be measured directly or calculated by moving one end of the chain by a known distance. Typically, the area to be surveyed is divided into triangles for effective surveying.
Compass: Using a prismatic compass, surveyors can measure angles effectively. This is typically combined with a chain to take distance measurements.
Photographic: Either land or aerial photography can be used to capture information about an area rapidly. In some cases, this may be combined with measurements of reference points to help determine the relative positioning of all the photographic data.
Plane Table: A plane table allows for fast surveying by plotting parts of the plan simultaneously. It is not the most accurate method. The plane table is used to transfer angular information from measurements to the plan.
Theodolite: A theodolite is a precise angle measuring tool. The device is zeroed using a reference point then horizontal and vertical angles can be easily calculated by pointing the targeting lens at the desired object. It is used with a chain to measure distances. However, the total station has largely replaced the theodolite.
Tacheometer: This is a special form of theodolite that has a stadia diaphragm and an anallatic lens. This eliminates the need for a chain because the distance can be calculated using the diaphragm. This method has been almost completely replaced by using a total station.
Total Station: This is a theodolite with an electronic distance measuring system. With the EDM, the distances can be measured without a chain. This can allow a single surveyor to capture much more information in a faster timeframe.

Measurements and Leveling

Distance measurements can be taken using electronic or chain measuring tools. However, they can also be calculated using trigonometry, particularly the Pythagorean theorem. Typically, angles are measuring using precision tools using the sexagesimal system. This divides a full circle into 360 degrees. Each degree can be divided into 60 minutes and each minute can be divided into 60 seconds. This makes a full circle 1,296,000 seconds, a very accurate system. Leveling is achieved by combining a spirit level or electronic level on an optic level. This is used to sight leveling rods to determine the relative heights of different areas of land. Sometimes GPS or an altimeter is used for larger-scale leveling.

Order Survey Supplies Today

If you are ready to start surveying, order your survey equipment from Engineer Supply. We have a broad selection of tools including total stations, theodolites, levels and much more. You can find everything you need for a basic project or a high-precision survey.

Frequently Asked Questions

Where Can I Buy Good-Quality Survey Equipment?

You can order all types of equipment for surveying from Engineer Supply. We have measuring tools, supplies for plans and blueprints, tripods, transportation equipment and much more. You can even find tools for your construction project after the survey is complete.

What Is a Theodolite?

It is a high-precision tool used for measuring angles while surveying. It is one of the central pieces of equipment used in modern surveying. Typically, total stations are used which combine a theodolite with an electronic distance measuring system. This makes surveying faster and easier.

What Types of Survey Equipment Do I Need To Get Started?

The most basic form of surveying can be done with just a distance chain and compass. However, most surveyors prefer to use total stations or theodolites and chains. In short, it depends on how accurate you need to be and what the environment is.

What Projects Require Surveying?

Any project that will require an accurate understanding of the land should include surveying. The most common examples are engineering projects such as construction or civil engineering. However, surveying may also be used for cartography or scientific data collection. Surveying is also often used in underground projects such as mining and archeology.

What Education Do Surveyors Need?

There are two main types of surveyors. Licensed surveyors usually need a university degree in surveying and need to meet the licensure requirements of their jurisdictions (often training and test). They can determine the legal boundaries of a plat for land. Engineering surveyors can only survey within an established property. They only need a certificate or on-the-job training.