(a) Direct labour construction
The promoter uses his own workforce to carry out construction. This gives the promoter full control of the work and flexibility to alter it. However, with no competition on prices, costs can be high unless management of the work is efficient.
Direct labour construction was common for works in Britain and for all sizes of projects overseas until the 1950s. It has continued overseas where sufficiently experienced local contractors are not available. Local authorities and public utilities in the UK continued to use direct labour for such as re-surfacing roads, constructing minor roads, laying water mains or sewers, etc. until the 1980s when the government required such jobs be opened to competition from contractors (see ‘Compulsory Competitive Tendering’ in Section 1.15). Direct labour construction can be undertaken by consulting engineers on behalf of the promoter. The consultants hire the necessary labour and plant, and order the necessary materials, using money provided by the promoter. This procedure was widely adopted up to the 1950s for projects in the UK and overseas, and can still be used now. It was used on some works for raising the Essex side of the Thames tidal defences 1974–1984. Given a small team of engineers and some skilled foremen to guide local labour under a resident engineer with strong managerial capacities, direct labour under the control of a consulting engineer has often been notably successful in keeping a project to time and budget.
(b) Construction divided into trades
Apractice often followed in developing countries is to split construction work into packages by trade, for example, brickwork, carpentry, etc. because local contractors often provide only one type of trade work. ‘Self-build’ houses in the UK often use this approach. The same approach on a larger scale is sometimes adopted for complex building projects, with a management contractor appointed to co-ordinate the work (see Section 2.5(b)).
(c) Main civil contractor supplies all ancillary services
Most civil engineering works incorporate services of an electrical or mechanical kind, such as for heating, lighting, ventilation and plumbing. It is usual to permit the contractor to choose the sub-contractors who provide such services, subject to the approval of the promoter. The promoter, however, must make provision in the design to accommodate such services.
An advantage to the promoter is that co-ordination of the sub-contractors then rests with the contractor, and if they delay him, that is his responsibility.
Adisadvantage is that if the promoter specifies (i.e. ‘nominates’) some particular supplier of services or goods, the promoter then becomes responsible for any delay caused to the civil contractor by the nominated firm.
(d) Civil contractor constructs; promoter orders plant separately When major plant such as generating plant, pumps, motors, or process plant has to be incorporated in civil engineering works, there is an advantage in the promoter letting separate contracts for such plant. This may be essential in cases where plant is on such long delivery time that it must be ordered before the construction contract is let. Adiscussion of the measures necessary to co-ordinate the plant contracts with the construction contract is given in Section 5.6. Advantages to the promoter are that he has direct access to the plant supplier to specify his requirements and agree all technical details. He can receive plant drawings in good time to complete the structural designs. Adisadvantage is that, if the plant supplier is late on his promised delivery, the promoter may have to pay the contractor for delay. To guard against this, plant delivery times quoted to the civil contractor can allow a ‘safety margin’ on the plant supplier’s quoted delivery time. The majority of all projects incorporating major plant are managed satisfactorily on this basis.
(e) Civil contractor orders all plant
On a large and complex project there may be an advantage in requiring the civil contractor to order plant, as specified and pre-agreed by the promoter with the plant supplier – provided the time for construction is long enough for plant to be delivered in time.
• The civil contractor can be left to arrange delivery of pieces of plant to suit his construction programme.
• The civil contractor has direct contact with the plant supplier to agree to the details of any storage or lifting requirements.
• The promoter avoids the risk of delaying the contractor by not getting the plant supplier to deliver in time.
• The plant supplier will not start manufacture until the civil contractor places his order.
• To complete the civil works design, the promoter may have to pay the plant supplier a fee for providing layout drawings in advance.
• If the promoter asks for some alteration to the plant, or a ‘works test’ on the plant shows the need for some amendment, delivery may be delayed causing the civil contractor to claim for delay.
• The plant supplier may increase his charges if he thinks his risks will be increased by having to rely on the civil contractor for payment.
(f) Plant supplier arranges building design and construction
Where the supplier of process plant exerts a dominating influence on the design of a project, the promoter may ask him to employ a civil engineering contractor as sub-contractor to construct the works to accommodate the plant. The plant supplier may then use some firm to design the civil works, or else he passes this also to the civil contractor.
Some plant suppliers, however, will not agree to this procedure, on the basis that either they have no experience of construction work or do not wish to be involved in it.