We're currently in the process of getting a baseline approved by the client, and would like to better understand how others get around the use of constraints. Presently we have no constraints in the schedule, but have placed certain activities into the schedule using a positive lag, instead of an ALAP constraint.
Our Client does not want use of constraints, but at the same time they do not want lags. We concur that we do not want any mandatory constraints, but do not want to have preferrential logic ties either as this will mean tying activities to others for convenience and will introduce inaccurate paths through the schedule.
In the old days when P3 a couple of constraints, now in P6 they have added several others, and i fear our Client doesn't fully understand how these additional types work - has anyone ever run into this sort of situation, and how did you overcome the clients reluctance in accepting constraints.
Our Client does not want use of constraints, but at the same time they do not want lags.
Your Client is a fool.
He start by placing a constraint on you, not to use constraints. Constraints are real life modeling needs, even mathematicians recognize constraints in linear programming models. Constraints are modeled in a way they cannot be substituted by functionalities that look equal but do not even fall into "similar".
Lags, activities and constraqints are modeled in a different way, they are all different. It is a fallacy they are equal.
Seems like he cannot absorb lags and constraints because they make it difficult for him to understand the schedule, but it is no excuse.
The problem is not with lags and constraints, the problem is with their wrong use, at times with wrong implementation by the software.
Is he of the kind that frequently gets his jobs into trouble that he needs more of a Forensic CPM than an Action CPM to be used as a tool for management?
Why being so dramatic about their use to go as far as to prohibit their use?
Even the infamous Must Start/Finish constraints have their valid use. How would you model the Phases of the Moon? Have you figured out how to stop the Moon?
Leads Lags and constraints should be used logically and as much or as little they are needed never bared. If a job consists of 100 activities ea driven by a contractual constraint, then let it be if this is the intention of the contract. Maybe he should allow for all except activities.
We suggest our customers to create a separate WBS Phase "External events" and use constraints but only for milestones belonging to this phase. Like Milestone "Site is available" may precede the works on site.
In this case schedule constraints is easy to explain and they become easy to manage.
Steve
Software Constraints are usually used to represent External events which are often found in contracts. For example halfway through a project a site becomes available for construction work to begin, this would often be respesented by Start Milestome with an Early Start Constraint the same as the contract date a nd a note crossreferenceing the contract paragraph.
Lead and Lags are used t represent when one job can start a time after another has started or before another has finished. If you do not use leads and lags then the activities have to be broken into two or more activities and the schedule become a lot more detailed. This is not so much of a drama as constraints.
Leads Lags and constraints should be used logically and sparingly but not bared.
On the other hand if you are doing a Monte Carlo on a schedule in P6 you must remove all leads and lags.
You have just got to educate your client.
Paul E Harris
Eastwood Harris Pty Ltd, Melbourne, Australia
Planning and Scheduling Training Manual & Book Publishers, Consulting and Training
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