Most of the construction projects involve laborious work which is to be handled by men and the machinery designed for doing the work undersigned.
It is difficult for workers to accomplish all things in a project and so there comes the need for machines particularly the construction equipment (machinery) that is widely used nowadays almost everywhere in the world.
For speedy and economic construction of a undertaking, proper choice of machinery is of preliminary importance for civil engineers. The versatile range of machinery available commercially involves the decision of people. There are few basic things that are considered in selection of suitable machinery. They are as follows:
Where the full utilization of new machinery for its entire working life is not foreseen, or its utilization on further undertakings is uncertain, it may be desirable to use existing old machinery even if its operation is somewhat more expensive. The depreciation cost of the new machine is likely to be high, and this would raise the owning cost of the machinery and thus the unit cost of work.
The equipment chosen must suit the conditions of the job, soil, valley, working conditions and climate of the region.
A minimum number of types should be acquired so that there is uniformity in the type of machinery on a job. A common type of engine should be selected for the different types machines such as excavators, dump trucks, tractors and scrapers that are on the project.
Larger machinery gives higher output on full load, but its cost of production on part load is usually greater than that of smaller units working on full load. Larger machinery needs correspondingly larger size of matching units, and shutting down of one main unit may render several other large units idle.
Transportation to works is generally difficult and costly. However, larger machines are usually more sturdy and suitable for tough working conditions. Servicing, maintenance and repair facilities have to be greater for larger units.
It is desirable to have machinery of same size on the undertaking. With standbys, the cost of larger size standby machinery is more than that of smaller size.
Fig: Construction Equipment
Standard machinery is often manufactured and is available. Such machinery is manufactured in large numbers and so readily available and moderately priced. Spare parts of standard machinery are easily available and are less costly. After the work is over, disposing off standard machinery and its spare parts is generally easier than disposing off non-standard or specialized machinery.
The economics of equipment is one of the most crucial considerations in the selection of equipment.
When calculating owning cost, all items of expenses, like freight, packing and forwarding, insurance, erection, commissioning, etc. should be included with the price paid to the supplier.
For imported equipment, it is preferable to import from a soft currency rather from a hard currency area, to save foreign currency reserves.
The availability of spare parts at reasonable costs during the entire working life of the equipment should be ensured while selecting a particular type or make of equipment, especially of imported equipment. Downtime due to shortage of spare parts commonly accounts for long idle periods during the working life of equipment. If specialists are needed, their availability should also kept in mind.
The machine selected must, if possible, be able to do more than one function and must be inter-convertible wherever possible.
It is good to have machinery of the same manufacturer on a undertaking as far as possible and to have minimum number of different makes of machinery. The quality and commitment of local dealers is crucial. They should be sincere and capable of extending prompt after sales service.
The locally available operators and technicians must be able to handle the machinery selected. A special machinery may have excellent performance but it may be difficult to handle it through available know-how.
If the machine is needed to work for only a part of its useful life then possibility on of disposing it off or its employment some other job must be considered. Obsolescence of the machine must not be overlooked.
We Thank Anilkumar Abburi for sharing this articles with civil engineers on The Constructor.