By José Luis Ponz-Tienda, PhD

• The relationships based on production levels,
• The cost curves, and
• The consumption of resources depending on its nature.

We wish that this example will be useful for all the Plexos´ fanatics.

The problem consists of the scheduling of a foundation slab with three cycles of concreting. It is considered that the relationships are start-to-start, from certain production levels of steel assembly.

The learning curve is referred to as the "efficiency curve" or "productivity curve" and is based on the fact that a worker needs time to learn how to carry out a specific task while increases its efficiency along the execution. Plexos uses the equation exposed below, being P the total of production for the activity; d, the duration of the activity; t, a period of time, and α, a discretional parameter to adjust the intensity of learning.

Changing the "Learning Curve Effect" of the Steel activity ("Acero") on the properties panel, the start of the activities "Ciclo Concreto 1" and "Ciclo Concreto 2" are adjusted until the required production level of steel assembly is achieved.

The learning effect delays the starting of activities by a start-to-start relationship and brings forward the finishing by finish-to-finish relationships.

Consequently, the histograms of resources and cost changes according to the distribution of the resources.

But not all resources have the same behavior in the learning effect. Handwork and Machinery do not modify its consumption; nevertheless, other resources as materials modify its consumption as the efficiency of Handwork and Machinery improves over time.

In the following images, the resource "Steel" is represented with the same learning curves than above, but in this case, the steel consumption is adjusted depending on the efficiency of the handwork over time.

Note that in the last histogram, the steel is over-allocated in the last three days of the activity due to the great efficiency of workers.