One of the most frequently encountered risks in civil engineering construction is that the ground conditions met during construction will not be as expected, because trial boreholes and test pits cannot reveal the nature of every cubic metre below ground level. This means that quantities of excavation, filling, rock removal and concrete, etc., for such as the foundation of structures or laying of pipelines actually found necessary may differ from those estimated.
The risk that the promoter will need changes also arises from the relatively long time it takes, often 2 years or more, to get a civil engineering project designed and constructed. During this time it is always possible for newer processes or equipment to be developed which the promoter needs to incorporate in the works, or there may be revised forecasts of demand for the project output.
The traditional way of dealing with these risks of change is for the design of the works to be completed first, and then to produce a construction contract for which civil engineering contractors are invited to tender. The price bidders tender for such a contract is based on a bill of quantities which lists the estimated quantities of each type of work to be done, taken off (i.e. measured) from the completed drawings of the works required. Against each item a contractor bids his price per unit quantity thereof, and these, multiplied by the estimated quantity of work to be done under each item, when totalled form the Contract Sum. This system permits the contractor to be paid pro rata to the amount of work he actually does under each item, and also eases valuation of the payment due to the contractor for executing changes to the design of the works during construction to overcome some unforeseen difficulty or make an addition.
The promoter can thus make reasonably small alterations or additions to
the works required during the construction period provided these are not so extensive as to change the nature of the contract.
A standard form of contract using the bill-of-quantities method, was first introduced by the UK Institution of Civil Engineers in 1945. This standard form, known as the ICE Conditions became very widely used, and in the 7th edition is known as the Measurement Version. Asimilar form of contract, known as the FIDIC Conditions, was developed by the International Federation of Consulting Engineers for worldwide use.
Abasic provision of both these standard forms is that the contract between the promoter and the contractor for construction of the works, is administered by an independent third party the Engineer who has the responsibility of seeing that the provisions of the contract are fairly applied to both promoter and contractor. The Engineer1 has power to ensure the contractors work is as the contract requires and issues certificates stating how much the promoter is obligated to pay under the terms of the contract. This avoided the bias that might occur if either the promoter or contractor decided these matters. The great majority of all civil engineering projects undertaken by British engineers in the UK and elsewhere have been, and still are, constructed satisfactorily under the ICE or FIDIC Conditions. However, other methods are also commonly used to meet special requirements as shown below, and the ICE and FIDIC have developed other standard forms for such purposes.