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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