Eg:
The plan of a site was prepared by using a 30m. chain. The area of the site drawn over the plan is 245cm². The chain used for the surveying was 10cm. too short. If RF = 1/150, calculate the true area of the site.
Calculation:
The area of the site on plan = 245cm².
RF (representative fraction)
= 1/150 = 1cm. /150cm. = 1cm /1.5m.
That means 1cm. on plan represents 1.5m. on the ground.
Therefore area of the site on the ground
= [245 × 1.5m. × 1.5m.]
= 551.25 m²
A1 = calculated area of the site
= 551.25 m²
L = designated length of chain
= 30m.
L1 = actual length of the chain
= [designated length - chain error]
= [ 30m. - 0.1m.]
= 29.90 m.
True area of the site
A = [A1 × ( L1 ÷ L)² ]
= [551.25 × ( 29.90 ÷ 30)² ]
= [551.25 × 0.9967² ]
A = 547.58 m²
To understand A to Z of surveying, click here.
Thank you for going through these calculation steps❤. Have a good day 😄.
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