ESTIMATION OF CIVIL WORK


ESTIMATION

Estimate is a calculation of various items of an engineering works so as to know its approximate cost and quantities of various kinds of materials required with labour involved for its satisfactory completion.

Purpose of Estimating

1-To ascertain the necessary amount of money required by the owner/contractor to complete the proposed work.

2-For public construction works, estimates are required in order to obtain administrative approval, allotment of funds and technical sanction.

3-To ascertain quantities of materials required in order to program their timely procurement.

4-To calculate the number of different categories of workers that are to be employed to complete the work within the scheduled time of completion.

5-To assess the requirements of Tools, Plants and equipment required to complete the work according to the program. 

6-To fix up the completion period from the volume of works involve in the estimate. 

7-To draw up a construction schedule and program and also to arrange the funds required according to the programming. 

8-To justify the investment from benefit cost ratio. (For ideal investment, this ratio should be more than one).

10-To invite tenders and prepare bills for payment. 

11-An estimate for an existing property is required for valuation.

DATA FOR ESTIMATE

  • DRAWINGS 

  • SPECIFICATION 

  • RATES

DRAWINGS

Fully dimensioned and to the scale drawings are required for finding dimensions while doing measurements.

Following drawings are required

PLAN -AT A SCALE OF 1 CM = 1 METRE

ELEVATION AND SECTIONAL ELEVATION -AT A SCALE OF 1 CM = 1 METRE

ETAILED DRAWINGS -AT A SCALE OF 1 CM = 20 CM

SPECIFICATION


  • GENERAL SPECIFICATIONS     

  • DETAILED SPECIFICATIONS

    RATES

    Rates per unit of various items of work include

    a. The rate of various materials which are used in
    construction

    b. Labour wages and categories

    c. Location of work its distance from source of material and cost of       transport 

  • Rates can be obtained from P.W.D. schedule of rate book or can be calculated by “ Analysis of Rates” method. 

ESTIMATE

IN PUTS

PROCESS

OUT PUTS

DRAWING

CALCULATION OF

REPORTS

SPECIFICATION

LABOUR (SKILLED, UNSKILLED)

PRELIMINARY ESTIMATE

RATES

MATERIAL (Course  FINE)

OR

 

CARRAIGES

DETAIL ESTIMATE


MEASUREMENT

Measurement has a very important place in Planning and Execution of any Civil Engineering work.

It is required from first estimate to the final completion of work and payment settlements. 

GENRAL RULES

Each item shall be fully described and shall include all necessary materials, transport, unloading, stacking, storing, wastage in handling, labour required for finishing the work etc.

Booking of dimensions is done in order of length, breadth or width and height or depth or thickness.

Dimensions shall be nearest

0.01 m in length

0.01 m2 in areas

0.01 m3 in volumes

0.001 tonnes in weights

Same work with different conditions or stages must be measured separately stating the condition, height or depth or distances.

UNITS OF MEASUREMENTS 

Mass, voluminous and thick works shall be taken in cubic unit or volume( M3).

Thin, shallow or surface works shall be taken in square unit or in area( M2).

Long and thin work shall be taken in linear or running unit (RMT)

Piece works or job works etc. shall be taken as number.







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