The chains used in measuring linear measurement may subject to wear and tear, or rupture which brings alterations in their original length (L). The chain either can expand or contract which causes a change in length (ΔL). Then, actually the length of the chain will be, L + ΔL which can be designated as L'.

If you take the chain of length designated as L to measure a particular distance of 'l'. Due to the error in the chain, the measured length would be l'. If the error is ΔL, then we can determine the correction factor.

L = True Length or Designated Length

ΔL = Change in length

L' = Actual Length or incorrect length = L +ΔL

Then correction factor is L'/L

Then in field, if we measure a length with this incorrect chain, then the measured length would be incorrect (l'). Then correct length l, is given by;

l = l' x  (L'/L)

1. Correction for Chain Length

True length (l ) = Measured Length (l') x (Actual length of Chain L')/ (Designated length of Chain L) 

l = l' x  (L'/L)

2. Correction for Area

A = A' x ( 1+ 2e)

e = ΔL/L

3. Correction for Volume

V = V' x ( 1 + 3e)

 Also Read:

  1. What is Compass Surveying?
  2. What is Principle of Surveying?
  3. What is Chain Surveying?
  4. Reconnaissance Survey and Index Sketch in Chain Surveying
  5. What is a Site Plan? What is the Purpose of Site Plan? When is Site Plan Required? What are the Types of Site Plans?
  6. Linear Measurements in Surveying