Network Diagram question

[Venkat]

Hi Saket,

in the attached there are network diagrams to calculate the relationships using precedence diagramming.

I'm getting ES = '8' for activity E, but it seems to be wrong.

Could you please clarify this?

Thanks a lot,
Venkat

[namita]

I think ES 8 is fine for E. Is there any other dependency?

[Venkat]

thanks, i recalulated today morning and got the answer as '8' and learnt never calulate critical path at midnight.

[indusharma]

Venkat ,

We will look into this quampus question

Regards

[saket]

Yes friends, you are doing great in calculating it

Critical Path with FF

CPM3.jpg (27.97 KiB) Viewed 7066 times

one more question, which activity has free float and what is the duration of that float ?

[namita]

I shall wait for sometime for some answers... before I do

[harin4627]

Activity "c" has one day free float

[indusharma]

Activity C is the only activity which is not on Critical path.
EF for C is 6, and LF is 7 (as if E need to start on 8th day, C can start as late as 7th day).

C has 1 day as free float

[namita]

Answer is correct. Just to elaborate on things we need to consider when we are talking about Free Float. Before anything else what is Free Float once again

The amount of time that a schedule activity can be delayed without delaying the early start date of any successor or violating a schedule constraint

So the important points when we think about Free Float are:

1. Is there more than one successor for the activity we are calculating the free float? If so, all successors ES should not be impacted. In current example this situation is not a problem as C has only one successor

2. Formula should be considering Start of successor activity/ies and finish of current activity

3. Free float can only come into existence if successor is having more than one activities converging on it or the successor activity is having constraint applied on it e.g. can not start before a defined date etc.... In our example E is having C and F so this condition is satisfying

So this is all about Free Float I have.. Anyone has anything more..please share

[indusharma]

Well explained Namita

[kripakrish]

In this diagram isnt cp =27 ?ABFEG=3+4+6+4=10=27? doesnt LF of G should be 27?or not necessary always.
For back ward pass would we start with LF of G as 21 or 27?

[namita]

As we have dependencies, CP length will be 21 in this case. Also LF will be 21 only

[Housam Bassal]

Yes friends, you are doing great in calculating it

CPM3.jpg

one more question, which activity has free float and what is the duration of that float ?

Saket,

I have question regarding the ES of activity E

If I calculate ES of activity E depending on EF of activity C it will be 6+1=7, however If I go by the calculation ES= EF-duration+1 = 11-4+1=8

What did you choose 8 and not 7 , is there any rule for that (for example as its ES , so we need to choose the Biggest number(forward method), and in case of EF we need to choose the smallest number(backward method)?)

Please clarify?

[manishpn]

Yes friends, you are doing great in calculating it

CPM3.jpg

one more question, which activity has free float and what is the duration of that float ?

Saket,

I have question regarding the ES of activity E

If I calculate ES of activity E depending on EF of activity C it will be 6+1=7, however If I go by the calculation ES= EF-duration+1 = 11-4+1=8

What did you choose 8 and not 7 , is there any rule for that (for example as its ES , so we need to choose the Biggest number(forward method), and in case of EF we need to choose the smallest number(backward method)?)
[b][i]Calculations are shown by Saket, you need to consider FF relationship and not relation between C and E[/i][/b]

Activity "c" has one day free float

Please clarify?