Deadline Constraint

[AJ]

I work for the space program, the Deadline Date for our projects depend on
the launch dates. So, if the launch slips, the deadline slips as well.

How can I constrain Deadline Dates between two tasks?

Help,

AJ

 

[Andrew Lavinsky]

Let me make sure I understand you.....

You have a launch date. The launch date is variable.
You have deadlines for various other activities. Those deadlines are variable
based on the launch date.

The question is whether you want a deadline or a predicted finish date for
the predecessor tasks.....

You have a couple options:

1) If the deadline is the launch date, create your predecessor tasks and
display the Deadline field. Copy the start date of the launch date into
the deadline field of the predecessor tasks. Instead of a routine paste
function, right click and Paste Special > Link > Text and this will put a
variable deadline on the predecessor linked to the launch field.

2) Use Start to Finish constraints on the predecessor tasks. This is quite
acceptable for circumstances where one task, like an audit, drives the completion
of predecessor tasks. In that case:

Predecessor Task = 1
Launch = 2

The predecessor field for Task 1 would read 2SF. You can insert lead as
needed, i.e. "2SF-5d." This will push the task back and forth based on the
launch date.

-A

 

[AJ]

Can you insert formula within the deadline column?

For example,

say you have "Launch date" in the deadline column (Row2) and you have have a
subsequent task "Stage" (Deadline column, row 3). Is there a way to insert a
formula in (deadline column, Row 3) stating "Stage=launch date - 10 days".

I want my deadline dates to be independent of my start and finish dates;
therefore, I dont want to use my predecessors for this.

thanks.

 

[Andrew Lavinsky]

You can't insert a formula in the deadline column, but depending on how adventurous
you feel, you could use two other date columns to do the trick:

1) Copy Launch Date Start and Paste Special > Link > Text to Date Column
A for the Stage Task
2) Calculate Column A - 10 days, and insert into Column B
3) Copy Column B and Past Special > Link > Text to the Deadline field for
the Stage Task.

It's a bit kludgey, but if you only use this technique a couple of times
in the project, it shouldn't use too many resources. If it slows everything
down, you could always switch to manual calculations, and then recalculate
the schedule as necessary.

-A

 

[Andrew Lavinsky]

Not sure what I was thinking. You can do the same thing with one custom
column:

1) Create a new custom date field. Set the field to calculate Start - 10d
2) Take the result from the field on the Launch task, and Special Paste the
link into the deadline field for the Stage task.

Same concept, but less taxing of your PC resources.

-A

 

[Paul Billings]

Not sure what I was thinking.  You can do the same thing with one custom
column:

1) Create a new custom date field.  Set the field to calculate Start - 10d
2) Take the result from the field on the Launch task, and Special Paste the
link into the deadline field for the Stage task.

Same concept, but less taxing of your PC resources.

-A

Instead of a custom date field, consider creating a new milestone task
linked to the Launch with the appropriate lead. PasteSpecial the
finish of the new milestone into the deadline field of the Stage
task. Same behavior, but a little more obvious what's going on.
(It's too easy to wipe out your custom date field that's specific to
that task with another formula that applies to all rows at some later
date.)

Paul

 

[Paul Billings]

Let me make sure I understand you.....

You have a launch date.  The launch date is variable.
You have deadlines for various other activities.  Those deadlines are variable
based on the launch date.

The question is whether you want a deadline or a predicted finish date for
the predecessor tasks.....

I would almost always vote for the predicted finish date for the
predecessors, allowing a milestone such as "Ready For Launch" move
around. (In other words, normal schedule logic without PasteSpecial
links.) The date of this milestone is what *you* can control. The
movement of the real launch date is somewhat out of your control, but
can be modeled as a single deadline (on the Ready For Launch task)
which is revised as it moves around. This allows you to easily give
an intelligent answer if you are asked, "How much do you need us to
delay the launch?"

Paul