Linear measurements — signs of standard corrections for tape tension and temperature Which of the following statements about the signs of standard tape corrections (tension and temperature) is/are correct in plane surveying?

Introduction / Context:
Accurate linear measurement with steel tapes requires applying standard corrections. Two of the most common are the tension (pull) correction and the temperature correction. Correctly assigning the sign of these corrections is crucial; otherwise, true lengths will be biased short or long, propagating errors into coordinates and areas.

Given Data / Assumptions:

• Standard (calibration) tension and temperature are known for the tape.
• Elastic extension is linear with applied tension (within working range).
• Thermal expansion is linear over the working temperature range.

Concept / Approach:
The conventional form of a correction added to the measured length is:
c_tension = (P − P_s) * L / (A * E) and c_temp = α * (T − T_s) * L.
When P > P_s or T > T_s, the tape lengthens, causing measured distances to be too small; therefore the correction to be added is positive. Conversely, when P < P_s or T < T_s, the tape is effectively shorter, making measured distances too large; the correction must be negative (subtracted) to reduce the measured length to the true value.

Step-by-Step Solution:

Verification / Alternative check:
Check by dimensional reasoning: a longer tape marks off fewer true metres per tape length, hence measured distance is underestimated and needs a positive correction.

Why Other Options Are Wrong:
Each individual statement (a)–(d) is correct, so “All of the above” is the only comprehensive correct option.

Common Pitfalls:
Forgetting the “add to measured when tape is longer” rule; mixing the sign convention when software expects corrections as “to be added.”

Final Answer:
All of the above