Factors of Production and Throughput in Construction
Rules for modeling combination of resources to produce output of construction procedures
All factors of production in the construction industry are complementary: a resource combines with other resources to produce output. For example, cement, aggregate, workers and machinery produces concrete. Complementary resources combine differently in different operations. Cement, for example, is used to produce masonry with bricks as well as concrete with aggregates.
We shall call a definite composition of certain resources to produce a throughput as a Construction Method. It is customary to write Method Statements for each activity of construction for clear understanding among involved parties. A method consumes material resources, while workforce (manpower and equipment), operates for a duration. Duration of the method is governed by the workforce with the lowest productivity.
Throughput of a construction method is quantified in the following types of measurements:
- Geometry Throughput such as counts, length, area or volume, is the commonest form of measurement.
- Transportation Throughput measures movement of a geometric unit over a distance or for a duration, such as haulage and lifting.
- Duration Throughput measures the productivity of two or more workforce in tandem. For example, a unit-duration composition of drilling rigs with drilling bits is used to compare the productivity of different types of rigs and bits to produce drill-holes.
- Nominal Throughput is a special case of geometry throughput, such as installation of transformers, that uses the geometry of a leading resource itself as the measurable.
- Non-measurable Throughput is a collection of resources that should be present on standby during other works such as cleaning, covering, shelter, storage, survey, barricade, diversion, scaffold, access, lifting, hauling, power, pump, safety, quality control, occupational health and tools.
The statement of composition of a construction method gives the contribution of each resource to unit throughput of production. Composition is used to calculate the requirements for projected throughput and reconciliation for achieved throughput. While the contribution of material resources can usually be expressed as a proportion of throughput, the contribution of equipment is influenced by various real-time site conditions. The types of composition of equipment are discussed in Productive and StandBy Scenarios of Construction Equipment.
When a factor of production always requires one or more other factors in a fixed proportion, the supporting resources are said to be supplementary to the main resource. Generators consume diesel, machines always require operator, aggregate spreader is mounted on truck, drilling rig works with drilling tools. Note that supplementary relationships are almost always associated with a workforce factor of production.
It should be acknowledged that a supplementary relation is a special case of complementary relation. It is particularly useful when equipment in a composition can be replaced by a substitute along with its supplement. For instance, a towed machine, along with supplementary tow-truck is equivalent to a self-propelled machine used for the same purpose. [Contrariwise, a specially designed machine that is a combination of two machines, does not make the two machines supplementary. An excavator-hoe is specially designed to act differently from front and back ends, excavator and hoe are not mutually supplementary.]
When similar equipment is associated with the same accessory, it is more useful to consider the relationship as complementary than supplementary. Foam release agents are used for all shuttering units and hence, simpler to be regarded as a complementary factor in shuttering. Similarly, it is implicit that all vehicles use fuel, all machines are handled by operators and that all human resource should carry requisite tools relevant to their trade. It is debatable whether these supplements should be kept to make calculations cumbersome. Such supplements are useful to estimate fuel requirement for standby plant during operation time.
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