Project Tasks Dependencies and Constraints
The network diagram is a logically schematic display provides graphical view for the project details like the tasks required to be performed, the relations between them and the duration’s estimations for the task itself and for the entire project including the earliest time to beginning the work in a every task the earliest predicted finishing date of the project. Network diagrams used for detailed planning, analyzing scheduling in project implementation and as a control tool in the monitoring and control phase. Two methods used to build the network diagram task-on-the-arrow (TOA) method and the recently one called the task-on-the-node (TON) method, or, the precedence diagramming method (PDM).
The relations between the two tasks called Dependency, Lowery and Stover describes the task dependency as "the logical connection, or link, between two tasks", (Lowery & Stover, 2001, p. 58). These relations defined according to the tasks predecessors and successors. Wysocki states four dependencies to describe and explain the relation between two tasks (Wysocki 2012, p.204 & 205):
Finish-to-start (FS), where task 2 cannot start unless the task 1 completed.
Start-to-start (SS), where task 2 starts when the task 1 start.
Start-to-finish (SF), where task 2 finish when task 1 starts.
Finish-to-finish (FF) where task 2 finish when task 1 finished.
My example here from my specific job and so sophisticated, cementing job, for FS, we cannot mix the cement slurry unless we finished add the chemical the water, mixing fluid, and mix them properly. For SS, we start pumping cement slurry on fly when we start mixing of the mixing fluid and dry cement. For SF, when the pressure rising up this means pumping displacement fluid finished. FF, example for SS dependency can be applied here when in fly mixing cement slurry mixing finish pumping finishing.
Constraints
The constraints between the tasks determine the dependencies between them. Single constrain can lead to any
The relations between the two tasks called Dependency, Lowery and Stover describes the task dependency as "the logical connection, or link, between two tasks", (Lowery & Stover, 2001, p. 58). These relations defined according to the tasks predecessors and successors. Wysocki states four dependencies to describe and explain the relation between two tasks (Wysocki 2012, p.204 & 205):
Finish-to-start (FS), where task 2 cannot start unless the task 1 completed.
Start-to-start (SS), where task 2 starts when the task 1 start.
Start-to-finish (SF), where task 2 finish when task 1 starts.
Finish-to-finish (FF) where task 2 finish when task 1 finished.
My example here from my specific job and so sophisticated, cementing job, for FS, we cannot mix the cement slurry unless we finished add the chemical the water, mixing fluid, and mix them properly. For SS, we start pumping cement slurry on fly when we start mixing of the mixing fluid and dry cement. For SF, when the pressure rising up this means pumping displacement fluid finished. FF, example for SS dependency can be applied here when in fly mixing cement slurry mixing finish pumping finishing.
Constraints
The constraints between the tasks determine the dependencies between them. Single constrain can lead to any
References: Lowery, G. & Stover, T. S. (2001) Managing Projects with Microsoft Project 2000. USA: John Wiley and Sons Inc., p 58. Wysocki, R.K. (2012) Effective project management: traditional, agile, extreme.6th Ed. Indianapolis : Wiley Publishing