Finish No Later Must Finish On / Deadline Constraints

[Chris]

Dear All,
Any guidance would be welcomed concerning constraints for this particular
scenario.

I have 10 tasks, A-J.
Tasks A-E are linked by 'finish-start' dependencies and are also 'as late as
possible' constrained.
Task F must finish no later than 31st Mar 2015. It is linked by a
'finish-start' dependency to previous Task E and also a 'finish-start'
dependency to subsequent Task G
Tasks G-J are linked by 'finish-start' dependencies and are also 'as soon as
possible' constrained.

I am unable to make Task F take up the finish date of 31st Mar 2015. It is
earlier - which I assume is correct as it must occur before that date.
However, I would have assumed that it would have been pushed back to that
date by the previous 'as late as possible constraints for Tasks A-E.

I converted Task F to a 'must finish on' constraint to see if this forces
the date to be 31st Mar 2015 but that doesn't seem to have the desired effect.

I also looked at the deadline function but am aware that this is more
advisory than constraining.

The confusing thing is that I have other projects that seem to take up this
constraint fine. I've checked to see if I have inadvertantly got links in
place which are causing the shift but cannot see anything untoward.

There is a !note in the information column which says "This task finishes on
30/01/12 which is different than its 'Must Finish On' constraint of 31/03/15".

I do need this task to finish on that specific date (perishable goods
leaving warehouse) - any guidance would be welcomed.

Regards
Chris

 

[Jim Aksel]

GIven a chain A-B-C-D where "C" has a must finsih on constraint.
First, use of MFO is strongly discouraged. If you use MFO for "C" and A & B
drive it to a later date, then you will see A and B with finish dates later
that the start of C and this does not make sense.

You seem to be going in the correct direction, Make A & B ALAP. Give C a
deadline and make it ALAP. The successors to C are ASAP. This asumes there
is other logic chains in your schedule for dates after the completion of C.
I assume also there are logic chains that start ealier than A and are not
related to this chain.
--
If this post was helpful, please consider rating it.

Jim Aksel, MVP

Check out my blog for more information:
http://www.msprojectblog.com

 

[Chris]

Hi Jim,

That's useful thanks.

Just to clarify - when you recommend giving C a deadline I am assuming you
mean just that - rather than a constrained date?

You're correct that there are 'start to finish' dependencies between all the
tasks, but none external to that (of enough importance to require inclusion).

I see what you mean about the potential for A&B to be later than C - I
suspect we would just have to throw A&B 'out the window' as Task C finish
date must be that 31st March 2015 otherwise the goods will perish, but they
can't go out before that as we have specific contract rates for specific
dates and the products would not have been packed until the last moent, hence
the need for the plan to show that specifc constraint.

Regards
Chris

 

[Jim Aksel]

Yes, "C" would have a deadline.
Something that is a business decision, you really can't throw A&B out the
window if they are necessary to create "C"

A: Catch Fish
B: Prepare Fish for the store
C: Ship to Store on contract date.

If you make all these ALAP with a deadline on C these are the complications
I see --

If it takes longer to complete any of these tasks than planned, you miss the
date, C. Your critical path is A-B-C guaranteed.
If A & B are moved to ASAP, then you probably need a buffer task which might
be "Freeze/Thaw the fish." It might come after A or after B depending on
what it takes to "prepare fish."

In any event, if you use MFO or FNLT for "C" you could end up with a
scenario where the schedule is telling you "Catch Fish" completes on
11/27/2017 which is two years later than you "C" -- ship fish. That will not
make sense. You could also play with "C" as FNET. Then if A & B run early,
the you have slack between B & C.

Your business sense and logic will tell you if A & B need to be ASAP or
ALAP. The difference, of course, is your total slack.

Let me throw something else in the mix. make A&B ASAP tasks. You could use a
spare date column and a formula where Date1 = [Late Start]- 5days or
something similar. Now you have to monitor A & B to make sure they start no
later than Date1 (you have a built in margin of 5 days). We did that on a
project and manually keyed the calculated date to a deadline.

--
If this post was helpful, please consider rating it.

Jim Aksel, MVP

Check out my blog for more information:
http://www.msprojectblog.com

 

[Steve House [MVP]]

A contraint will cause Project to place the task in the schedule so it
always obeys the constraint, regardless of whether it is actually possible
for things to work out that way or not. For example, a FNLT constraint on a
milestone "Product Leaves Warehouse" of 01 March will prevent it from ever
being scheduled later than that date, EVEN IF the required predecessors
don't even start until April. In other words, the schedule is lieing to
you. IMHO, the primary benefit to using the software is to figure out the
workflow that will allow you to meet your delivery requirements. To that
end, it needs to be free to tell you whether a given trial workflow is going
to be successful or not, predicting for you what will happen if you commit
to the plan as you currently envision it. If your trial workflow would make
you miss your deadline, you need to let Project reveal that fact to you by
placing the task on the date it WILL hit rather than just showing it to you
happening on the date you WANT it to hit.