Early Finish Calculated Incorrectly? Please help soon!

[PlanMan]

I have a situation where I want to use early start/ early finish dates to
represent the planned start/finish of a task by constraining the first task
in a series where the project is calculated from the project finish, and
everything is allowed to go to ASLAP. Thus the project would be statused
relative to all ASLAP or critical dates for summary progress. (Understand
that this project will grow to 30,000 lines and this is an easy way to
determine critical dates, also the majority of work is in planning package
form). The problem is when progress is made on the first task ahead of time
the early work not completed is pushed to ASLAP so that early finish = finish
which is incorrect if allowing the task to be split (thus losing all of my
planned info) and if the task is not split the tasks are statused relative to
the in progress task, which is also something I do not want. Should I
customize a field? If so how? The only thing I can think of is to baseline
the planned info and to update accordingly Thanks ahead of time.

 

[Rod Gill]

I agree with Trevor, scheduling from a finish date is a disaster (and many
hundreds of wasted hours) waiting to happen!!

Schedule from start and if things don't finish on time you know you have to
add more resources or adjust links.
--

Rod Gill
Microsoft MVP for Project - http://www.project-systems.co.nz

Author of the only book on Project VBA, see: http://www.projectvbabook.com

Do you get the feeling that you are doing it the hard way?
Why not re-think the original approach, since it is not working for you?
Setting everything to ALAP and scheduling backwards from a finish date is
just a bad idea from the outset
Show it to me and I'll fix it.
--
Trevor Rabey
0407213955
61 8 92727485
PERFECT PROJECT PLANNING
www.perfectproject.com.au





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[Steve P]

PlanMan:

I too use MS Project ALAP scheduling. I use it to emulate mrp scheduing
(backward-pass) in a production manufacturing setting showing the latest we
need to start and/or finish assemblies to meet a product delivery date. We
provide the mfg manager a list of assemblies by start date that should be
worked. The mfg manager then chooses which assemblies he can start based on
the available resources (labor and equipment).

I initially schedule exactly as you do, put a ALAP constraint on the
earliest predecessors. As you status the schedule you will need to do one of
the following:

1. Set all tasks as 'Start No Earlier Then' that you want to maintain the
ALAP dates (zero Total Slack) including the initial ALAP tasks. As you start
a task and remove the constraint, the other tasks will not move forward. If
one of the 'In Progress' tasks is driving the schedule negative, the critcal
successors will be negative as well. If ALAP was used on these successors,
they would not show as negative Total Slack.

2. Set all tasks with the ALAP constraint to 'Start No Earlier Then'. As you
start a task and remove the constraint, the successors will need to have the
constraint changed to ALAP, then changed to 'Start No Earlier Then' to set
the late start date.

In both cases, if one of the 'In Progress' tasks is driving the schedule
negative, the critcal successors will be negative as well. If ALAP was used
on these successors, they would not show as negative Total Slack. I prefer to
use option #2.

All 'In Progress' tasks must have constraints removed to properly calculate
negative Total Slack. If you don't, some tasks that should have negative
Total Slack will show zero Total Slack.

Disclaimer: I do not recommend this process for all types of schedules, only
those to emulate a mrp type (not MRP II) of process as for manufacturing
similar to SAP, Oracle, Baan, etc. MRP II requires first backward-pass, then
forward-pass resource leveling. As I recall, MS Project only does
forward-pass resource leveling.

http://www.businessdictionary.com/definition/backwards-scheduling.html

Hope this helps...

Steve P