Short Answer:

Errors in traverse surveying are small mistakes that occur while measuring angles or distances between stations. These errors affect the accuracy of the survey and can lead to incorrect positions and layouts if not corrected. They are usually caused by problems in instruments, human mistakes, or environmental factors.

Common errors include wrong angle reading, incorrect distance measurement, poor leveling, instrument misalignment, and environmental issues like wind or temperature. These errors are minimized using proper techniques, adjustments, and error correction methods like Bowditch or transit rule.

Detailed Explanation:

Errors in traverse surveying

Traverse surveying involves the measurement of a series of connected lines with angles and distances to determine the exact position of points. While this method is widely used for its flexibility and accuracy, various types of errors can occur during fieldwork or calculations. These errors must be identified and corrected to avoid mistakes in plotting and layout.

Errors in traverse surveying are generally grouped into three main categories:

1. Instrumental errors

These errors are caused by imperfections or faults in the surveying instruments used, such as the theodolite, compass, chain, or tape.

Misaligned telescope: If the line of sight is not in line with the axis, angles may be wrongly recorded.
Worn-out chain or tape: If the measuring tape is stretched or damaged, it gives incorrect lengths.
Loose screws or clamps: If the theodolite’s clamps or screws are not tight, it may shift slightly during measurement.
Improper calibration: Instruments that are not regularly checked or calibrated can give inaccurate results.

2. Personal or human errors

These are caused by mistakes made by the surveyor during the measurement process.

Wrong angle reading: Reading the wrong number from the scale or reading from the wrong vernier.
Incorrect alignment: Failing to aim the telescope properly at the target.
Improper centering: If the instrument is not exactly centered over the survey point.
Recording mistakes: Writing down the wrong angle or distance value.
Parallax error: If the eyepiece and object are not properly focused, the reading will be incorrect.

3. Natural or environmental errors

These errors occur due to outside conditions that affect measurements.

Temperature changes: Heat can expand measuring tapes or cause the instrument to drift.
Wind: Strong wind can shake the instrument, especially when measuring long distances.
Slope or uneven ground: Makes it harder to measure accurate horizontal distances.
Magnetic interference: Affects compass readings if there are nearby metallic objects or electrical equipment.

Impact of errors

Even small errors can add up across a long traverse and cause the survey not to close properly. This is called traverse misclosure. It means the final point does not meet the expected location. If left uncorrected, such errors lead to incorrect boundaries, wrong layouts, and issues in construction.

How to reduce errors:

Use properly calibrated and well-maintained instruments.
Level and center the theodolite correctly before use.
Take face left and face right readings and average them.
Recheck all measurements and keep careful records.
Use Bowditch or transit rule to balance and adjust closing errors in closed traverses.

Conclusion

Errors in traverse surveying can occur due to instruments, human mistakes, or natural conditions. Identifying and correcting these errors using proper methods and adjustments ensures accurate results in mapping, boundary marking, and construction layouts.