Short Answer:

Random errors in surveying are small, unpredictable variations that happen during measurements. These errors occur by chance and do not follow any fixed pattern. They can be caused by sudden wind, hand movement, or slight instrument vibration.

Unlike systematic errors, random errors cannot be corrected directly because they are not consistent. However, their effect can be reduced by taking repeated measurements and using the average value, which helps improve the accuracy of the final result in surveying.

Detailed Explanation:

Random errors in surveying

Random errors in surveying are those errors that occur by accident and without any predictable pattern. These errors are usually very small and happen even when all instruments are properly adjusted and the surveyor follows the correct method. They are unavoidable in real-life fieldwork but can be minimized through careful procedures.

In surveying, we rely on precise tools and techniques to measure distances, angles, and elevations. However, despite our best efforts, slight inaccuracies always remain due to factors that are outside our direct control. These inaccuracies are known as random errors.

Causes of random errors

1. Human limitations
   • Slight shaking of the hand while holding an instrument
   • Inconsistent reading of the scale
   • Small delay in noting observations
2. Environmental factors
   • Sudden gusts of wind moving the instrument or the leveling staff
   • Sunlight glare affecting the sighting
   • Light refraction due to air temperature change
3. Instrument behavior
   • Minute vibrations in optical instruments
   • Minor fluctuations in electronic instruments

Even though each of these changes may be very small, when combined, they can lead to small differences in the final reading. Since these errors occur randomly, their direction and size vary each time the measurement is repeated.

Characteristics of random errors

• Unpredictable: They do not follow any fixed trend.
• Small in size: Usually, they only affect measurements slightly.
• Equal chance of over- or underestimation: The error can make the result a little too high or too low.
• Average out over time: Repeated measurements help cancel out the effect.

How to reduce random errors

1. Repeat measurements: Taking readings multiple times and calculating the average reduces the effect of random errors.
2. Use of better-quality instruments: Instruments with finer accuracy and low vibration are less likely to produce random errors.
3. Proper field techniques: Standing steadily, shielding instruments from wind or sunlight, and using proper sighting methods can help.
4. Standard training: Ensuring that surveyors are well-trained and consistent in their actions minimizes human-caused variations.
5. Balanced observations: Taking measurements from opposite directions and comparing them helps in detecting abnormal values.

Random errors are not completely removable, but their influence can be brought down to an acceptable level. Since they are part of all measurements, modern surveying includes ways to deal with them, especially through statistical analysis.

Conclusion:

Random errors in surveying are unavoidable and arise from unpredictable human or environmental factors. They do not follow a fixed pattern and may increase or decrease the measurement slightly. Though these errors cannot be directly corrected, taking repeated readings and averaging the results can help reduce their effect. Managing random errors is an important part of achieving accuracy and reliability in any surveying project.