By José Luis Ponz-Tienda, PhD
In this example, a 10-floor building is scheduled in three different ways. First, the “traditional way” using simple activities; second, using “fragmentable” activities, that allows to execute the work in a non-continuous way; third, using subactivities as “repetitive activities” in order to show the differences between the traditional scheduling methods and the lean project scheduling way.
We wish that this example will be useful for all the Plexos´ fanatics.
- Traditional (Not Fragmented). Considering not fragmentable all the activities (Continuous option selected) as with the traditional scheduling software. This cause the activities to be totally critical (See the example "cases of criticality").
- Fragmented. Considering fragmentable all the activities (Continuous option unselected for each activity), allowing Plexos to establish the optimal fragmentation point. This cause the activities to be partially critical (See the example "cases of criticality").
- With Subactivities. Considering fragmentable all the activities (Continuous option unselected for each activity), but replacing the traditional activities for repetitive activities (takts), guarantying the taks' flow (interchange between production packages) and allowing more flexible an realistic schedules.
Note that in this case, but not always, the obtained starting and finishing times are the same. However, for the third case, the internal subactivities change its times.
Discretional fragmentation/continuity is very useful to provide more realistic schedules and closer to real conditions of the projects. Additionally, the correct application of the discretionary continuity can reduce the project makespan and avoid the reverse criticality.
Additionally, working with sub-activities allow us to schedule complex problems with multiple crews.