Schedule around subtask end date

[ssilk99]

Hi everyone,

I have a project where I want to schedule backwards for the
predecessors of a certain mid-point task, and forwards for those after
it. Here's a detailed description of the problem.

The tasks in the project, in order, are Estimate, Design, AFE,
Construction, Records Updated, and Close.

The only date that is rigid is the end date of Construction, which is
the date the customer needs delivery. Other than that, I just want to
schedule things in the most efficient timing possible. So, I want to
set a fixed end date for Construction, then make the first three tasks
schedule backwards from there so I can figure out when each should
start. So, if customer requires item by January 10th, and Construction
will take 5 days, it should start on the 5th. Then, if AFE takes three
days, it should start on the 2nd, and so on. After the Construction end
date, the remaining tasks should schedule forward.

When all this is done, if I enter a longer task length for any of
Estimate, Design, AFE, or Construction, I should see the start date of
the project move back, whereas if I enter a longer length for Records
Updated or Close, I should see the end date of the project move
forward.

Right now when I try to do something like this, I get a scheduling
conflict, with two tasks happening simultaneously, and flow arrows
looping back in time.

I'm using Project 2000.

Thanks.

 

[John]

Hi everyone,

I have a project where I want to schedule backwards for the
predecessors of a certain mid-point task, and forwards for those after
it. Here's a detailed description of the problem.

The tasks in the project, in order, are Estimate, Design, AFE,
Construction, Records Updated, and Close.

The only date that is rigid is the end date of Construction, which is
the date the customer needs delivery. Other than that, I just want to
schedule things in the most efficient timing possible. So, I want to
set a fixed end date for Construction, then make the first three tasks
schedule backwards from there so I can figure out when each should
start. So, if customer requires item by January 10th, and Construction
will take 5 days, it should start on the 5th. Then, if AFE takes three
days, it should start on the 2nd, and so on. After the Construction end
date, the remaining tasks should schedule forward.

When all this is done, if I enter a longer task length for any of
Estimate, Design, AFE, or Construction, I should see the start date of
the project move back, whereas if I enter a longer length for Records
Updated or Close, I should see the end date of the project move
forward.

Right now when I try to do something like this, I get a scheduling
conflict, with two tasks happening simultaneously, and flow arrows
looping back in time.

I'm using Project 2000.

Thanks.

ssilk,
Your schedule scenario has a basic conflict. Normally your schedule is a
good candidate for reverse scheduling. However, the "end date" you need
constrained is not really the end date - there are two more tasks after
it.

There are various ways to deal with your situation. Here is the approach
I recommend although there may be other equally effective methods
available. First, set up your plan with normal forward scheduling. I
would start by setting a Project Start Date that is well before the date
the first task needs to start. For example let's say your construction
deadline is 1/20/06 and that each of the tasks leading up to it are 5
days duration each. Mentally working backwards, that says that the plan
needs to start somewhere mid December '05, so set a Project Start Date
(Project/Project Information) sometime before that. Next, set a Deadline
(insert the Deadline field as a column) of 1/20/06 for the Construction
task. Finally, lay in all the tasks with a finish-to-start link and the
estimated durations. On the Gantt display you will see the deadline date
with respect to the Construction task. Now, here's the mundane part.
Manually adjust the Project Start Date so the Finish Date of
Construction equals the deadline date. This process could be automated
with a VBA macro.

If you need to change a pre-construction task duration or set a new
deadline date, repeat the Project Start adjustment process.

I agree, this process isn't real pretty and hopefully someone else has a
better solution, but with the addition of the VBA automation, this
process will meet your needs.

Hope this helps.
John
Project MVP