I need drawings 6 weeks before starting a Phase
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Hello Andrew
nothing against a negativ lag ... as long as the link is FS and the lag is less than half of the duration of the predecessor.
What is more important, the schedule, or the techniques used to get to the proper dates??
In my opinion, the use of negative lag is appropriate in some situations, but using it may throw off a Monte Carlo analysis...
I feel that P3 was created to support the use of negative lag, therefore it can be used...Some project controls people are against the use of it, but I am not...
Hope your schedule works out okay...
Fair comment if youre in complete control of the planning.
In this situation though, Im not and I need the 6 week negative lag in the plan so that its picked up by the searchlight as I check through my several Projects that I have on the go at any one time.
Thanks for your comment though, its much appreciated.
I think making a predecessor out of a successor by using a negative lag is nice drawing but very bad planning.
How can can you do proper follow-up of your progress? You can only find out that yr drawings are late at the moment construction works start.
Thanks Bijaya,
In truth, what happened, I wrote the post and sent it. While I was waiting, I re-read all the posts again and picked up your reverse SS suggestion. Tried that and it worked.
Then Rodel came along and confirmed what Id just tried and got working. My thanks should have gone to you as well for the original tip.
Youve both been a great help as with others on the forum. Im now getting more and more confident with using P3. Its a shame its been stuck in a box for so long not being used because I found it so hard to not only get into, but use on a daily basis to produce meaningful information.
Good to know it worked. If you read them carefully you will find that I had given you the same solution in my earlier reply back on 10 April.
Thanks Rodel, to the rescue again. It now works a treat.
I also noticed that it still wasnt quite working properly, showing only 4 weeks instead of 6. I hunted high and low for an explanation. I discovered that in my fragnet, I had one line which was using the 7 day calendar that I had created for weekend working, which I was now using for drawing issues. I fixed that :)
Terry,
Use SS with negative (-6week) lag and a successor of fixed starting date. If the data date is greater than the negative lag then it will sit on data date unless you put actual date.
Im still having problems getting this to work. They all appear on the Data date rather than 6 weeks before the start date of each phase.
To try and answer your questions about what Im trying to do. Im working for a Contractor who has stipulated dates for starting a phase. He is required to give us drawings 6 weeks before each phase, but these are not drivers of the phase. I.e. if hes late with the drawings, we still have to start on the fixed dates no matter how late the drawings arrive.
To be fair he is quite good, but I want to get the items in the right places so that I dont miss the drawing issues and can chase them if theyre due.
Drawings are always predecessor (or are important) before the Phases start. My point was that when you put zero float constraint on Drawing milestone, these milestones will appear as critical activities. And in reality, there is nothing that prevents the Drawings being ready more than 6 weeks before Phases start.
The reason Drawings are shown as milestone is that it is done by another firm or another department. (Or else drawing is an acviity in itself with its own dependincies and resources (within Design team).
By introducing a Drawing milestone in construction programme, one is trying to shown the end date of drawing activity (which in reality) is not dependent on any of the activities in the programme. But the activity in the programme (Phase) depends on having the drawing 6 weeks in advance.
In this context, it may be worth calling drawing milestone as "Deadline to get drawings completed Flag" and it can remain 6 weeks ahead of Phase.
Bijaya,
I tend to agree with you but it’s all depends on the situation. We don’t know the whole scenario and we can’t say it’s wrong to show that way.
“Terry said: The Phases all start on a specific date, and the contract state that we should have the drawings 6 weeks before that date.”
We can interpret that the drawings is the driver to start the Phases and it means it is critical. Why? How can we start phases or construction without any drawings to base on? (one scenario) We can constrain the milestone from 6 weeks before the phases start if this is not the start milestone so it won’t move on the data date when it was not yet due.
We can also interpret that the drawings is not that important for phases need to start and does not requiring any drawing to start with. (I haven’t encounter one but it might be the case) So you can consider that is not critical and we can used your solution.
For a construction contract only and not an EPCM it may vary on their scope whether they have IFC drawing before moving to site or they may have a preliminary drawing for quotation or bidding purposes only. In this case IFC drawing is the driver for them to proceed the construction phase otherwise they don’t have any basis of correct layout, details and constructability of their scope.
Either way is a correct approach depends on correct picture of the problems.
Regards,
Rodel
Rodel,
If you just have Drawing milestone as FS predecessor to phase, when you reschedule it, all the milestones will appear along the data date. For the presentations purpose, you may put zero float constraint to those milestones 0 then they will appear 6 weeks or whatever lead is specified before phases.
In doing so, the milestones will appear in your crtical path filter and there are many instances, you would not like to show them as critical activities because they are not. In such situation, some times I tend to give a reverse SS link - from phase to milestone with required negative lag. The direction of arrow in relationship appear wrong but otherwise, everything is correct in this way. it will be telling you when the drawings are required for each phase.
Hi Terry,
You can create a milestone (Drawings) as a predecessor with FS relationship on all phases and put log if necessary before all the phases can start. This milestone will trigger if the phases are ready to start.
Regards,
Rodel