FF/SS with lag/lead and Forward/Backward Pass Calculation

[JNB]

Hi,

How does Project calculate earliest and latest dates (times) for the following
cases ?
Task 1 (predecessor) and Task 2 (successor) linked with Finish-to-Finish or
Start-to-Start dependency with lag or lead time.

I've found a couple of CPM tutorials on the internet but they only contain
examples
of Finish-to-Start dependency. Is there a particular reason for that ?

Thank you in advance for any information.

Best Regards - JNB

 

[Jan De Messemaeker]

Hi,

To reply you I would have to create two such tasks and look at the result.
Why don't yiu?
HTH

--
Jan De Messemaeker
Microsoft Project Most Valuable Professional
+32 495 300 620
For availability check:
http://users.online.be/prom-ade/Calendar.pdf

 

[Dave]

Probably because he hoped that there was an expert who already knew the
answer. If that is the case then the expert's answer is probably more
likely to be correct than any experimentation by the OP.

 

[Jan De Messemaeker]

Right you are. Sorry.

--
Jan De Messemaeker
Microsoft Project Most Valuable Professional
+32 495 300 620
For availability check:
http://users.online.be/prom-ade/Calendar.pdf

 

[JNB]

Jan,

I've already tested and repeat my question. Pls feel free not to post if you
have
nothing to post in reply to my question. HTH.
--

 

[Dave]

You have plenty of support, Jan.
"Teach a man to fish...."

Although if you just give him a random collection of bits of wood, line,
bent metal and some strange worm-like objects, it might take him a long
time to figure it out.

Actually I am an enormous fan of working things out myself but I also
recognise that there are substantial numbers of people who simply can't
do it.

 

[Jan De Messemaeker]

Hi,

Well, moest people think I should answer (but nobody else does) so I'll try.
In fact, why I answered so enigmatically, is that the true answer to your
question implies the whole logic of PCM calculation... and that would be a
little tough in the framework of this newsgroup.
And why you will not find much documentation on it is because it is terribly
hard to explain in words.
Still, let me try.

For a SS link, Early start of the successor is larger than or equal to
(depending on the other links to the task, and on constraints) the START of
he predecessor plus the lag if any.
For a SS link, Late start of the predecessor is less than or equal to
(depending on the other links to the task, and on constraints) the START of
the sucecessor less the lag if any.

For a FF link, Early finish of the successor is larger than or equal to
(depending on the other links to the task, and on constraints) the finish of
he predecessor plus the lag if any.
For a FF link, Late finish of the predecessor is less than or equal to
(depending on the other links to the task, and on constraints) the finish of
the sucecessor less the lag if any.

Does this help?

--
Jan De Messemaeker
Microsoft Project Most Valuable Professional
+32 495 300 620
For availability check:
http://users.online.be/prom-ade/Calendar.pdf

 

[JNB]

Trevor,

Thank you for your reply. I really appreciate it. As an engineer, I do not
prefer
to use trial and error technique when studying a subject serious like CPM
since
every information you get from trial and error needs verification. I was
studying
the book by Timothy C. Kister and posted that question to better understand
some
CPM operations. I cannot say the people relying on my knowledge that I learned
this from trial and error.

In my opinion, there are some factors defining the quality
of this discussion group: one of them is the attitute of so-called experts
when replying messages. It also affects how people feel about the product
which is
Microsoft Project especially when deciding or preparing feasibility reports
for
software selection.

It is obvious that this is not the right place to look for answers. Next
time I will go
with planning plannet or some other groups. Better yet, I can go with
Primavera.