Was reading MIP 3.8 (Collapsed as-built method) and on page 75 there is Figures 7 & 8 under conversion of As-Planned logic to As-Built logic.
In Fig 7 there is a link between activities 2 & 4 of FS(0). (It say float equals 4 days but it should read 5 days).
In Fig 8 that link is replaced with a FF(5) link between activities 2 & 3 and it MAKES activity 2 critical, (in fact it makes all activites critical).
1. Can anyone think of why you should replace float, (a variable time period), with a lag, (fixed time period)?
To me, float varies, lag doesn’t, they are not interchangable. The difference between Fig 7 & 8 is that in Fig 7 activity 2 can be delayed by up to 4 days, (or 5), without affecting activity 4. In Fig 8 ANY delay to activity 2 is going to delay activity 4, i.e, a complete change of logic and result when rescheduling.
2. Is the paper advocating that it’s ok for someone to change logic to MAKE an activity critical, surely that’s fiddling the programme and not allowed.
3. In Fig 7 there is no relationship between activities 2 and 3 at all, (2 affects 4 but not 3), so where has the relationship from 2 & 3 suddenly come from? In Fig 8 a delay to the finish of activity 2 will now delay the finish of activity 3 - but that was never the case in Fig 7.
You do have to remember that this is in the context of collapsing a programme, not looking forward, but whichever way the same points arise. Working through a few scenario’s, i.e. activity 2 finishing earlier or later, same for activity 3, etc, you get different results using the logic in each fig.
Anyone got any comments on what the AACE document is trying to say here?
In Fig 7 there is a link between activities 2 & 4 of FS(0). (It say float equals 4 days but it should read 5 days).
In Fig 8 that link is replaced with a FF(5) link between activities 2 & 3 and it MAKES activity 2 critical, (in fact it makes all activites critical).
1. Can anyone think of why you should replace float, (a variable time period), with a lag, (fixed time period)?
To me, float varies, lag doesn’t, they are not interchangable. The difference between Fig 7 & 8 is that in Fig 7 activity 2 can be delayed by up to 4 days, (or 5), without affecting activity 4. In Fig 8 ANY delay to activity 2 is going to delay activity 4, i.e, a complete change of logic and result when rescheduling.
2. Is the paper advocating that it’s ok for someone to change logic to MAKE an activity critical, surely that’s fiddling the programme and not allowed.
3. In Fig 7 there is no relationship between activities 2 and 3 at all, (2 affects 4 but not 3), so where has the relationship from 2 & 3 suddenly come from? In Fig 8 a delay to the finish of activity 2 will now delay the finish of activity 3 - but that was never the case in Fig 7.
You do have to remember that this is in the context of collapsing a programme, not looking forward, but whichever way the same points arise. Working through a few scenario’s, i.e. activity 2 finishing earlier or later, same for activity 3, etc, you get different results using the logic in each fig.
Anyone got any comments on what the AACE document is trying to say here?