Constraints

Here’s a related discussion:



http://www.planningplanet.com/forum/forum_post.asp?fid=1&Cat=2&Top=9096



Bernard Ertl

eTaskMaker Project Planning Software

I ONLY use two types of date constraints, the "Early Start" (which works as a start-no-earlier) and "Late Finish" (which works as a finish-no-)later.



1) These do not break the CPM rules

2) The more types of constraint you use, the harder it is to follow the schedule

3) Any type of real-world constraint can be modelled using one or both of these.



The Expected Finish constaint is a DURATION, NOT a date constraint. It has a "set it and forget it" functionality in recalculating remaining duration automatically as the data date moves which can be very dangerous to those of us who believ every actoivity should be measured each progress reporting cycle.

Mandatory finish constraints do not consider CPM requirements. They force the activity to occur at that time, even if its predecessors are not finished. The activity cannot occur any earlier and cannot occur any later, even if it would be advantageous to do so. I always recommend that people do not use this logic-override constraint.

Mandatory finish constraint, or expected finish constraint or early finish constraint



My practice; -

Mandatory finish constraint - Seldom to use since the calculated float will be zero by this constraint, float of successor activities are affected and the scheduled picture may misleading by the "amount of affected float"

Expected Finish Constraint - If I cannot work out the duration of the activity by resource and quantity, this constraint will be used. Both quantity and resource are in flexibilty and hardly to set limit or forecast

Early Finish Constraint - This depend the programme structure, case depends on using Early/Late constraints. Anyway, all contract listed conditions like milestone, key date, handover dates, etc, they are constrained by this category