Construction Management ဘာသာရပ္ကုိ အျခားေသာ -အင္ဂ်င္နီယာ ေလာကမွ ေလ့လာနုိင္ရန္ တင္ျပျခင္းျဖစ္ပါသည္။ -Dr. Tin Tun ( 17-8-2014 ) 4:35 am The development of construction procedures 1.1 The nature of civil engineering work Virtually all civil engineering structures are unique. They have to be designed for some specific purpose at some specific location before they can be constructed and put to use. Consequently the completion of any civil engineering project involves five stages of activity which comprise the following: 1. Defining the location and nature of the proposed works and the quality and magnitude of the service they are to provide. 2. Obtaining any powers and permissions necessary to construct the works. 3. Designing the works and estimating their probable cost. 4. Constructing the works. 5. Testing the works as constructed and putting them into operation. There are inherent risks arising in this process because the design, and there¬fore the estimated cost of the works, is based on assumptions that may later have to be altered. The cost can be affected by the weather during construction and the nature of the ground or groundwater conditions encountered. Also the promoter may need to alter the works design to include the latest technical developments, or meet the latest changes in his requirements, so that he does not get works that are already out-of-date when completed. All these risks and unforeseen requirements that may have to be met can involve additional expenditure; so the problem that arises is – who is to shoulder such additional costs? Clearly if the promoter of the project undertakes the design and construction of the works himself (or uses his own staff) he has to meet any extra cost arising and all the risks involved. But if, as in most cases, the promoter engages a civil engineering contractor to construct the works, the contract must set out which party to the contract is to bear the cost of which type of extra work required. The risks involved must also be identified and allocated to one or the other party. 1.2 The most widely used contracts for construction 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 lay¬ing 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 ten¬der 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 pay¬ment 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’. A similar form of contract, known as the FIDIC Conditions, was developed by the International Federation of Consulting Engineers for worldwide use. A basic 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 contractor’s 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 (see Chapter 4).
Posted on: Sat, 16 Aug 2014 23:27:00 +0000
Trending Topics
Recently Viewed Topics
© 2015