Basic Principles Of Surveying

There are many types of surveying but basically two types of surveying are the major ones.

     

1.  Working from whole to the part:

• Start with a Control Network: The survey begins by establishing a broad control network or reference points that cover a larger area. These control points are usually well-known, fixed positions with known coordinates (latitude, longitude, and elevation).

• Break it Down into Smaller Sections: Once the large-scale control network is in place, surveyors then work on smaller sections of the land or territory. This approach helps minimize potential errors and ensures that the smaller, detailed surveys are anchored in a broader, more accurate context.

• Error Minimization: By working from larger, well-established points to smaller ones, surveyors can identify and correct any errors early on. Any discrepancies are more easily detected at the beginning, before they accumulate and affect the smaller-scale measurements.

       2. Location of a Point by Measurement from Two Points of Reference:

      This method involves measuring the distances from at least two known points (or stations) to the unknown point. The procedure is:

• Step 1: Identify two known reference points (A and B) with known coordinates.

• Step 2: Measure the distances (d₁ and d₂) from each of these reference points to the unknown point (P).

• Step 3: Using these distances, draw two circles around points A and B with radii equal to the distances (d₁ and d₂).

• Step 4: The point where these two circles intersect is the location of the unknown point (P).

If there are additional reference points, more circles are drawn, and the point of intersection gives the position of the unknown point.

Example:

If you know the distances from points A and B to the unknown point P, you can use these distances to form a system of equations that allows you to compute the coordinates of P. This technique is commonly used in GPS technology, where distances to multiple satellites are used to triangulate an exact position.

Consistency in Measurement

• Measurement should be consistent. If measurements are not checked, there can be deviations due to instrument errors, human error, or environmental conditions. Therefore, it is essential to always check and recheck the measurements.

There are other several other types of principles such as:

3. Never Keep Two Errors of the Same Kind

• This principle recommends that errors should be of different types (positive and negative), which helps balance out the effects of mistakes. By ensuring that errors don’t systematically occur in one direction, the overall accuracy of the survey is maintained.

4. Use of Proper Instruments

• Proper instruments like theodolites, total stations, levels, compasses, and GPS should be used to ensure accurate readings. Instruments should be calibrated, maintained, and used correctly to avoid measurement errors.

5. Closing the Survey

• A survey should be closed by ensuring that the starting and ending points of the measurements align or meet. This is a common method to check for errors, especially in triangulation or traverse surveys. If there’s any discrepancy, it can be corrected.

6. Leveling the Instrument

• When using instruments like theodolites or levels, it’s crucial to ensure that the instrument is perfectly level. An unlevel instrument will introduce errors, especially in elevation readings.

7. Triangulation

• Triangulation involves measuring angles and distances from known reference points to establish the position of unknown points. It’s especially important in large-scale surveys and for determining precise locations over long distances.

8. Chain of Evidence

• All surveying work must be properly documented with detailed notes and records. The surveyor must maintain a clear and reliable chain of evidence to support the accuracy and validity of the measurements taken.

By following these principles, surveyors can ensure the integrity of their measurements, reduce the chances of errors, and produce reliable maps and data for various applications such as land management, construction, and resource planning.