Understanding Task Dependencies in Project Management
There are four different task dependencies (relationships): Finish to Start (FS): The finish date of predecessor task determines the start date of. They establish the relationships among the tasks. They are listed The first task must start before the second task can finish. The task "assign. When you link two tasks, you create a relationship between them called a By default, Project creates finish-to-start links, but those don't work in every situation.
This is the most common type of dependency and is the default type of dependency that Project uses. In a finish-to-start dependency, the second task in the relationship can't begin until the first task finishes.
Dependency (project management) - Wikipedia
So, for example, if you were planning a project to make a wedding cake, you might use a finish-to-start dependency between the "Bake cake" and "Decorate cake" tasks. When the "Bake cake" task is finished, the "Decorate cake" task begins. Start-to-start SS dependencies are used when the second task in the relationship can't begin until after the first task in the relationship begins.
Start-to-start dependencies don't require that both tasks start at the same time. They simply require that the first task has begun, in order for the second task to begin.
Types of task links
Going back to the wedding cake example, let's say you had planned to make the icing for the cake while the cake is baking in the oven.
You can't start making the icing until the cake has started baking, so you might use a start-to-start dependency between the "Bake cake" and "Make icing" tasks. If one of your tasks can't finish until another one finishes, you can use a finish-to-finish FF dependency between them.
Finish-to-finish dependencies don't require that both tasks be completed simultaneously.
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They simply require that the first task be finished, in order for the second task to finish. The second task can finish any time after the first task finishes. In our wedding cake example, let's say there are some finishing touches to the decorations that you can't finish until the cake is delivered.Primavera - Utilizing a Start to Finish Relationship
You can use a finish-to-finish dependency between the "Decorate cake" and "Deliver cake" tasks. When the "Decorate cake" task is finished, then the "Deliver cake" task can be completed.
Both leads and lags can be applied to all 4 types of dependencies. PMBOK defines lag as "the amount of time whereby a successor activity will be delayed with respect to a predecessor activity".
When building two walls from a novel design, one might start the second wall 2 days after the first so that the second team can learn from the first. This is an example of a lag in a Start-Start relationship. In accordance to PMBOK a lead is "the amount of time whereby a successor activity can be advanced with respect to a predecessor activity For example, on a project to construct a new office building, the landscaping could be scheduled to start prior to the scheduled punch list completion.
Task Relationships | Nenad Trajkovski
This would be shown as a finish-to-start with two-week lead". It would be much faster and less expensive, to install the pipes first, place the concrete to actually build the wall around the pipes, and finally paint the walls. Shoring of the trench has to be done not necessarily immediately after excavation, but within certain time, otherwise the trench will collapse.
Vaccination of baby has to be done not immediately after birth, but within certain time Renewal of the passport has to be done some time after the current one has been issued, but before it expires. Invoice payment does not have to be done immediately, but within certain time after it has been issued.
Maximal-type relationships are rarely implemented in the project management software, most probably because with this feature it is too easy to create contradictory dependencies.