Re: Buffer or lag periods

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As you've discovered, lags aren't the same as a buffer. A lag time of,
say, 3 day between tasks means that there MUST be a 3 day delay between
the completion of the first task and the start of the second. For
example, perhaps you'll always need 3 days of curing time between
pouring concrete in the first task before starting to paint it in the
second task. No matter what date task 1 ends, task 2 should not start
until 3 days later.

Frankly, the best way to use the buffers is to include them in the
task's duration estimate. You say you don't know duration but you can
estimate it. If you think work will require 40 man-hours and you knw
you can have your resource full time, the duration will probably be 40
hours as well (5 days). So to add a 25% buffer set the duration to 50
hours. Or if you don't want to disturb the work estimate, set the
duration to 50 hours and assign the resource at 75% - work will be 40
hours.
--
Steve House
MS Project MVP
Visit http://www.mvps.org/project/faqs.htm for the FAQs



"SR" <SR@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:5DE79B5A-6975-4173-9C29-3AE5069422B1@xxxxxxxxxxxxxxxx
Thank John but may be i was not clear earlier.

I do not at all touch the start & finish date. that is why to adjust
the
date i put this lag.
lets say I have Task A - efft hrs 16 hrs & Task B - eff hr - 32 but
the dur
i don't know and hv one resource (not 100%) actual %ge not available.

If i simply schd B after A with Start-Finish, it will finish in 6 days
with
no lag. But then since the resource is not available 100%, A is not
going to
finish in 2 days. So what i do I keep "TaskAFS+5 days" in predecessor
col.
that gives me 5 days and i can maitain my baseline dates. but if the
takes 4
days and when i enter the actual finish date, it automatically adds
another 5
ds for Task B to start. I have to manually go and reduce the lag days
to 2 so
that the next task start can start on time.

What I am asking here is, is there any way to have this buffer so that
i
don't deviate from baseline dates and also keep some extra room for
each task



--
sr


"John" wrote:

In article <94E7E50F-EA84-457E-9883-DD8490F2E0AE@xxxxxxxxxxxxx>,
SR <SR@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Hi,

I am working in a functional unit projs where resources work in
multiple
projs. My prob is, when i create my plan, i only know the
estimated hrs for
each task and the % of resource availability. So it is really
difficult for
me to schedule the exact dates that a particular task is going to
finish. The
way I am doing is, take resource as 100% available and keep some
buffer days
(lag) for the next task to start. this i do by adding lags for the
next task.
e.g - if a 16 effort hrs task starts on 7/3. my schd will have an
end date
for this task 7/4 and with a lag of 5 days, next task will start
7/12.
Problem here is - when the task finishes on 7/10 with no effort
variance, the
start date for next task automatically set to 7/18 for 5 lag days.
I then
have to remove this lag to start on 7/11.

Saying that - cann't put date contraints as actually do not have
any
- duration available for the proj is always much
higher
than estmated hours.
- should not vary from the baseline dates for
main tasks as
the resource are blocked for the baseline dates for other
functional groups.

Does any one has any idea how to fix this problem or a better
solution to
schedule the task.

SR,
Your scenario is very typical - you have an estimate for the number
of
hours required to do a task and you know who you want to work on it.
The
problem I see in what you have described is that you appear to be
"forcing" the schedule, perhaps even doing something you should not
and
that is to directly entering start and finish dates for tasks.

The whole reason for using Project is to allow it to schedule your
project based on some basic inputs - task description, estimated
duration, schedule logic (links), estimated work, and resource
assignments. Is your plan going to be perfect? No, it never is.
Remember
most of the data is estimated so the initial schedule is a best
guess
estimate of how the plan will unfold. As the plan is executed, it is
updated and modified as necessary to reflect newer information.

It is also not clear if you understand the difference between
duration
time and work time. Duration is the time during which a task will be
completed. It is expressed in working time as the difference between
the
Start and Finish fields. Work on the other hand is the amount of
time
one or more resources will expend actually performing the task. If a
single resource is assigned at 100%, then duration and work will be
the
same. However it is also very common to have a duration time that is
longer than the work time. For example, painting a room may take 5
days
but the estimated work to paint the room may only be 30 hours.

It is very rare that you will have all the resources you want/need
to
complete your plan. It is also very rare that there is actually
enough
time to execute the plan as you would like. Those are the realities
of
the business world. Your job is to create the most reasonable but
realistic plan with the assets available to you. If you truly can't
get
there from here, then you need to make your case to your management
for
more time and/or resources.

John
Project MVP



.

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