According to RTU Syllabus

SURVEYING

LINEAR AND ANGULAR MEASUREMENTS

Part-8

Correction to Tape measurements-

1. Correction for standardization.
2. Correction for slope
3. Correction for pull
4. Correction for sag
5. Correction for temperature
6. Correction for mean sea level
7. Correction for Mis-alignment

Correction for Sag

• If the tape is standardized on flat and when used is supported between two ends,correction for sag will always be negative.
• It is because chord length will always be less than arc length.

Correction for Misalignment

• If the survey line is not accurately ranged out,the error due to misalignment occurs.
• The measured distance ABC will always be greater than the correct distance AC.
• Hence the error is positive and the correction is negative.

A

B

C

B

1

Correction for Mean sea level

• The measured lengths at different altitudes are sometimes reduced to a common level generally called Mean sea level.
• The measured distance at any altitude '"h"above mean sea level would be greater than the equivalent length at mean sea level.
• so correction will be negative always.

D-L

ADITI SHARMA