Constraints in P6

Hi John

The correct answer is never use any of them as they distort the logic of the programme.

There is a case to use ALAP on third party milestones such as Power On and delivery of Free Issue Materials.

Also "must start on" for the very first activity milestone otherwise none at all.

Best regards

Mike Testro

John,

Go to the help menu of primavera and search for "constraints". It will give you a good definition of what the effects of each type are are.

However in summary:

-"Start" types affect start dates, and "finish" types affect finish dates

-"On or before" types affect late dates, and "On or after" types affect early dates

-"On" types affect both early and late dates

-"Mandatory" types will ignore logic to maintain the mandatory date, and calculate total float for preceding activities based on this mandatory date

-"ALAP" pushes an activity out as late as possible without delaying any sucessors (ie zero free float)

Be aware some software are particularly bad at handling multiple constraints, at times yielding erroneous results.

http://www.planningplanet.com/forums/primavera-version-pm5-pm6/517280/primavera-p3-and-suretrak-wrong-dates-under-multiple-constra