(1) Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?
(2) It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.
Hi all,
This is my first post on Planning Planet so I'd like to introduce myself. I'm working on a multi high-rise project in Brisbane, QLD, Australia and although I have a few projects under my belt, this is my first job as Project Planner. We use Primavera P6 V7 Project Management here and I am basically required to plan and schedule two programmes - a client-issued programme and a subcontractor-issued programme.
The programme includes procurement, design, construct (substructure and superstructure), fitout and handover. Currently we are mid-way through substructure and I am having some trouble tracking the critical path. Depending on how I relate / lag the foundation piling with bulk excavation and the retention system, the critical path seems to "disappear" until fitout begins. As a remedial fix I have included links to Finish Milestones with finish constraints so that subcontractors still see a critical path on their weekly month-lookahead programme issue. However, I think this is a bit of a bandaid fix, but I can't seem to find any errors in my logic that are causing the critical path to disappear. Can anyone suggest what I can try to get a critical path running through the project? It's obvious what the critical path is on-site, but I want to reflect this in the programme (particularly as we have had a LOT of rain in recent months and EOT's are coming in left right and centre).
Kind regards,
Reece
Printer-friendly version
Send to friend
My dear Watson don't forget references to other project files that might be driving some of your job chains of activities.
Take a copy of the programme, remove any temp fixes you've put in, and go to the earliest activity which does (correctly) show critical.
Check what is driving the start of this activity -either a precessesor relationship or a constraint.
If it's a constraint, that's your problem.
If it's a relationship:
check to see if it's on a different calendar than the critical successor. eg if the predecessor is on a 7 day calendar and finishes on a Friday, but successor is on a 5 day Mon - Fri calendar and hence starts on a Monday, the predecessor will have 2d float before it goes critical. To show this predecessor as critical, when scheduling, go to options and select Define critical activities as longest path.
If it's on the same calendar, the most likely reason is out of sequence working. -ie at some point an activity has started or finished without one of it's predecessor rules has been met, or one if it's constraints being satisfied. To check this, schedule the programme and view the scheduling log. At the bottom of this log, it will list all Activities with unsatisfied constraints & Activities with unsatisfied relationships. A quick way to fix this problem is to select Prorgess overide rather than retained logic scheduling option, but best practise is to understand why this out of sequence working occured, and manually amend the logic / constraints to reflect reality.
If none of the above solves your problem, let us know and we can dig a bit deeper.
Cheers,
G
The most obvious events that obstruct the view to critical path are finish date constraints that create negative float (no matter if contractual or not, it fools the math) the use of different calendars and resource leveling. The most forgotten but cause of confusion as well are out-of-sequence events.
For a better view:
You got to accept not always critical path is visible as a continuous path, no matter if you define critical path as longest path or by using float it can still be displayed as discontinuous. Still no matter if using corect resource critical float values.
Daniel just said, "Critical Path changes as the job progress", well in the same way it changes as you look for strategies to get on time your job. Many times in this search I got lost, the only way to figure it out has been by trial and error modeling different scenarios and let the schedule run tell me about what is the effect.
Hi Reece,
You need to check a couple of things, first you need to check that the programme is logically link and that there are no loose ends. Second - make sure that there are no artificial constraints other than what the contract calls for, for example, if there are interface contraints then those are considered valid.
As you update the programme you will find out that the critical path will change as works are progressed at different pace (meandering path) and this is what yo need to track. Identifying the critical path is very important as it helps the management push the right buttons and get the project completed on time.
Bet regards,
Daniel
Email: PPadmin@planningplanet.com
Replies