Recipes: Custom Precedence Types

Dimi

September 28, 2018 17:59

Dependencies among operations are illustrated with precedence relationships. These relationships indicate the order of which the operations need to be performed.

Recipes, are Construction Method Models (CMM)* that illustrate the activities as boxes in a network diagram, in between of which the necessary dependencies are defined.

COMMON PRECEDENCE TYPES

The most common types of dependencies are the following four (4):

1. Finish - To - Start (FS): Activity B can begin after A is finished.

In other words: Finish A ≤ Start B

2. Start - To - Start (SS): Activity B can start at the same time as A.

In other words: Start A ≤ Start B

3. Finish - To - Finish (FF): Activity B can finish at the same time as A finishes.

In other words: Finish A ≤ Finish B

4. Start - To - Finish (SF): Activity B can finish at the same time as A starts.

In other words: Start A ≤ Finish B

ALICE CUSTOM PRECEDENCE TYPES

In ALICE, the above relationship types are extended, by adding the "At" type which imposes the type of dependency. Therefore, the additional precedency types are transformed to:

1. Finish - At - Start (FaS): Activity B must begin after A is finished.

Or: Finish A = Start B

2. Start - At - Start (SaS): Activity B must start at the same time as A.

Or: Start A = Start B

3. Finish - At - Finish (FaF): Activity B must finish at the same time as A finishes.

Or: Finish A = Finish B

4. Start - At - Finish (SaF): Activity B must finish at the same time as A starts.

Or: Start A = Finish B

Be mindful when using the custom precedence types as they impose a very strict relationship between activities, that can render your schedule as infeasible.

Further Resources