All about civil construction knowledge- PARAM VISIONS

Rate analysis of the JCB excavation for the building footing./ Calculating the cost of excavation done by JCB.

 Let us make a cost analysis of the excavation of the footing pit by JCB for the below-given drawing.



To excavate the footing pit of the above dimension by JCB, we have to take 8" to 1 ft. extra on either side of the pit as shown below.






The extra cutting is necessary, as the JCB bucket does not cut the footing pit sides in vertical lines & perpendicular to each other (as shown above). 
Let us consider the maximum extra dimension, by extending the length & width by 1ft. on all four sides.

Given data:

Adjusted size of the footing pit = 6ft. × 6ft.

Depth of footing pit = 5ft.

No. of footings = 12nos.


The volume of the total excavation

= 12nos. × L × B × H

= 12nos. × 6ft. × 6ft. × 5ft.

= 2160 cu ft.


The market rate for the JCB excavation is INR 800/-  to INR 1200/- per hour., depending upon the regional availability & demand.

Let us consider an average rate of INR 1000/- per hour, for the calculation purpose.

The excavation capacity of the JCB ranges from 700 cu ft. to 1100 cu ft. per hour, depending upon the type of soil & bucket capacity.

Let us consider an average excavation capacity of 900 cu ft./ hour for the calculation.


The cost of excavation of all the footings

= [(Total vol. of excavation ÷ excavation capacity/hr. ) × JCB rate

= [(2160 cu ft. ÷ 900 cu ft/hr. ) × INR 1000/-

=[2.4hour × 1000/hour ]

= INR 2400/-  (theoretical cost)

But when we do the excavation practically, the JCB takes 3mins. extra time per footing, to reset in line with individual footing.

Total time taken by JCB,

 = [(Total vol. of excavation ÷ excavation capacity/hr ) + ( extra time to reset) ]

= [(2160 cu ft. ÷ 900 cu ft/hr) + (no. of footings × extra time per footing )]

= [ 2.4hour + ( 12nos. × 0.05 hrs )]

{as 1 hr. = 60min., 3min = 0.05 hr.}

= [ 2.4 hour + 0.6 hour ]

= 3 hour.


The actual cost of excavation 

= excavation time × JCB rate/hr.

= 3 hour × 1000/ hr.

= INR 3000/-

Thank you for going through this article. Have a good day😄

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2 comments:

  1. super sir ... thanks for sharing your knowledge without any expectation.wish you all success in life ...may christ bless your efforts

    ReplyDelete
  2. Dear sir the post is excellent we need you to solve for all kind of rate analysis which will be helpful for fresher and experienced engineers who can gothrough once with doubt.

    ReplyDelete

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