critical activity with floating end date

[ketanco]

my activity B has two successors. G with SS relation, and D with FS relation

all of them are critical

so B and G are critical because of their SS relation

but finish date of B is not pushing D, there is a 1 day gap. D is pushed by something else

I checked all float dates for B and everything shows 0. I understand that Total Float is 0, but all other floats also relate to start date of B then? so although B end date has 1 day of float it doesnt mean anything?

[JulieS]

What is the driving predecessor to Task D? Is D linked to another task as well?

[ketanco]

let me write the relations and durations of these actvities only as the rest of activities are irrelevant.
Activity B : (Dur: 2 days) (Pred: irrelevant) (Succ: G(SS), D)
Activity D : (Dur: irrelevant) (Pred: B, G) (Succ: Irrelevant)
Activity G : (Dur: 3 days) (Pred: B(ss)) (Succ: D)

and all are critical in the schedule

So as you can see, B is making G critical by affecting its start date, and Both B and G are pushing D with FS. since D is 1 day longer than B, there is a 1 day float for finishing B. So although Start of B can not move, and the program says Total Float is 0 and I understand that, still we could make B 1 day longer, and the job would not delay. but all types of floats still show 0. so does it mean, all types of floats only depend on start dates?

[JulieS]

The reason task B is critical is due to the relationship (SS) with G. Float is determined by the forward pass (calculation of early start and early finish) and the backwards pass (late start and late finish). If there is no difference between a tasks Finish and Late Finish or Start and Late start, the task is critical.
Take a look at the Schedule table to see late start and late finish. The dates will match task B's start and finish.

[ketanco]

yes B is critical because of SS relation to G. and yes, critical activity is determined as you say. and here is also B finsih and Late finish date is same. because program thinks B's duration of 2 days as a fixed unchangeable thing.

but as you can see there is a 1 day gap between B end date and D start date. in other words, lets say B starts, and while performing B, something happens and B slows down and finish by 1 day delay. it will still be ok, no delay to the project will occur, although B is critical. Because B is only critical because of its start date, and NOT its finish date. and where is this information reflected? I assume nowhere?

[JulieS]

The fact that the finish of B can be delayed by one day (currently) is not reflected anywhere directly in this release. G is the driving predecessor and you can see that in the task inspector for Task D. Task B is not listed in the inspector window as it is not currently driving D.

[ketanco]

by saying in this release do you mean all MS project versions? but as far as scheduling terms is there a definition for this? although MS project doesn't cover it?

[JulieS]

In Project 2013 you can view all successors or driven successors as well as all predecessors as well as driven predecessors.

I do not know if there is a scheduling term for this.