Degree of Accuracy in Surveying
In surveying, accuracy refers to how close a measured value is to the true value. The degree of accuracy indicates the precision and reliability of survey measurements. It is an important concept that helps surveyors evaluate the quality of their work. For ITI Surveyor trainees, understanding the degree of accuracy is essential for producing reliable survey data.
Definition of Degree of Accuracy
Degree of accuracy is defined as the ratio between the error in measurement and the total distance measured.
Degree of Accuracy = Error / Total Distance
It is usually expressed as a ratio such as 1 in 1000, 1 in 5000, etc.
Example
If an error of 1 meter occurs in measuring a distance of 1000 meters:
Degree of Accuracy = 1 / 1000
This means the survey has an accuracy of 1 in 1000.
Types of Accuracy
- Absolute Accuracy: Closeness of measurement to true value
- Relative Accuracy: Comparison of accuracy between measurements
Factors Affecting Accuracy
- Quality of instruments used
- Skill and experience of surveyor
- Environmental conditions (wind, temperature)
- Method of surveying
- Errors in measurement and recording
Classification of Accuracy
| Type of Survey | Degree of Accuracy |
|---|---|
| Rough Survey | 1 in 100 to 1 in 500 |
| Ordinary Survey | 1 in 500 to 1 in 5000 |
| Precise Survey | 1 in 5000 and above |
Importance of Degree of Accuracy
- Ensures reliability of survey data
- Helps in selecting appropriate surveying methods
- Reduces errors in construction work
- Improves quality of maps and plans
Methods to Improve Accuracy
- Use high-quality instruments
- Perform proper adjustments
- Take repeated measurements
- Maintain equal sight distances
- Apply necessary corrections
Precautions
- Avoid careless observations
- Record data carefully
- Check calculations regularly
- Work under suitable weather conditions
Application in Surveyor Trade
Degree of accuracy is used in all types of surveys such as chain surveying, compass surveying, levelling, and theodolite surveying. It helps in determining whether the results are acceptable or need improvement.
Conclusion
The degree of accuracy is a measure of the precision of survey work. It helps surveyors assess the quality of measurements and ensures reliable results.
For ITI Surveyor trainees, understanding and maintaining accuracy is essential for successful and professional surveying work.