Estimate

An estimate is calculation or computation of the quantities of materials needed for a particular work and expenses likely to be incurred in the execution of the work.

Necessity

• To assess the financial requirements.
• For obtaining the approval and sanction of component authority.
• To access the economic feasibility of the project.

Types of estimates

• Preliminary estimate or rough cost estimate.
• Detailed estimate
• Revised estimate
• Supplementary estimate

Preliminary estimate

• To decide the financial involvement for AS by the authority.
• Cost of major components should be shown separately.
• Brief report and site plan needed.
• Prepared based on practical knowledge and similar works undertaken in the past.

Detailed Estimate

• Based on the plan and sectional drawings.
• Details of the works.
• Quantities of different items of works.
• Cost of each item.
• Contingencies etc.

Revised Estimate

• It also a detailed estimate.
• Prepare when original sanctioned estimate is likely to exceed during the execution of work.
• New components incorporated.

Supplementary Estimate

• Detailed estimate of the additional work.
• Is prepared when additional works are required to supplement the original work.

Preparation of estimates

• Rates of items are worked out based on detailed data providing cost of materials, conveyance charges and labour as per schedule.

Data

• The data book deals with the quantities of materials and labour required for different items of work.
• Will remain unchanged by fluctuation in market rates.

SOR-Schedule of Rates

• Prepared by the chief engineer PWD Administration.
• Data from economics and statics department and current market rates are taken into account.
• Is for estimating purpose.
• Followed for original and maintenance works.
• Consist of 2 volumes.

Conveyance Statement

• Actual distances are used.
• Taluk conveyance not used.
• Certificate- “The distances noted in the data for conveyance from quarry or source have been personally verified by me and are found correct. These are the minimum leads require.
• Rates available for lorry load, head load and boat load.
• For hilly areas 15% increase in rates are allowed.

Lead

• Lead or distance for removal-horizontal distance between the vertical central line of the pit cross section and the bank which is formed with the excavated material.
• Measured in units of 50m.
• Shortest practicable route.

 

Lift

• Vertical distance.
• ½ depth of the pit excavated +½ the height of bank formed with excavated earth + difference in level between the top of the pit and bottom of the bank.

Earthwork Excavation

• Excavation in difference material to be estimated separately.
• Ordinary soil- Any material yield to the application of mammati, spade or shovel.
• Hard soil- Any material which requires the application of picks or scarifies to loosen.