Levelling is a critical process in civil engineering that involves measuring the relative heights of points on the ground or on structures. The process is used to ensure that the structures being built are level and stable, and that they comply with building codes and regulations.
Despite the importance of levelling, there are several common errors that can occur during the process, and these can affect the accuracy of the measurements and lead to problems in construction. In this article, we will discuss some of the most common types of errors made in levelling in civil engineering.
1. Instrument Errors
One of the most common errors in levelling is instrument error. This occurs when the instrument used to take the measurements is not calibrated correctly or is not functioning properly. Instrument errors can result in incorrect readings, leading to inaccurate measurements.
2. Human Errors
Another common error in levelling is human error. This can include errors made by the person taking the measurements, such as misreading the measuring rod or not holding it steady. Human errors can also result from errors made in recording or transcribing the data.
3. Parallax Errors
Parallax errors can occur when the person taking the measurement is not aligned properly with the instrument. This can result in a shift in the angle of measurement, leading to inaccurate readings.
4. Refraction Errors
Refraction errors can occur when the light used to take the measurement passes through a medium of different densities, such as air and water. This can cause the light to bend, leading to incorrect measurements.
5. Temperature Errors
Temperature errors can occur when the temperature of the instrument or the environment changes, leading to a shift in the dimensions of the instrument or the object being measured. This can lead to inaccuracies in the measurements.
6. Curvature and Spheroidal Errors
Curvature and spheroidal errors occur when the earth's surface is not flat. This can lead to inaccuracies in the measurements, especially when measuring over long distances. Corrections for these errors can be made by using specific calculations and adjustments.
7. Tilt Errors
Tilt errors occur when the instrument used for levelling is not level. This can result in incorrect readings and can be corrected by adjusting the instrument and ensuring that it is level before taking the measurements.
Levelling is a critical process in civil engineering, and accuracy is essential for ensuring the safety and stability of structures. Common errors made in levelling include instrument errors, human errors, parallax errors, refraction errors, temperature errors, curvature and spheroidal errors, and tilt errors. By being aware of these potential errors and taking steps to minimize them, engineers can ensure that their levelling measurements are accurate and reliable.