Addressing issues related to negative slack

[Wendy]

Hi,

I have a plan that is now displaying with negative slack. The only
constraints listed on the plan are Start and Finish No Earlier than.
There are no deadlines in the plan. How can I figure out the cause of
the negative slack and work to fix it?

Any suggestions?

Thanks!
Wendy

 

[Jan De Messemaeker]

Hi Wendy,

Unless there are external links to other projects, negative slacks only
happen when there are No Later Than or Must constraints.
Find them ans your problkem will be solved.
Insert the column "Constraint type" and use the autofilter to locate the
culprit(s)

HTH

 

[John]

Hi,

I have a plan that is now displaying with negative slack. The only
constraints listed on the plan are Start and Finish No Earlier than.
There are no deadlines in the plan. How can I figure out the cause of
the negative slack and work to fix it?

Any suggestions?

Thanks!
Wendy

Wendy,
If after trying Jan's suggestion, you find that you indeed do not have
any FNLT or MFO constraints, the likely culprit is an Actual Start on a
successor task. For example, let's say you have two tasks linked
finish-to-start. Both task show "0" total slack. If you then enter an
actual start date for the successor task that is earlier than it's
scheduled start date, that will cause the total slack of the predecessor
task to go negative. The fix is simple. Obviously the finish-to-start
link between the two task is no longer valid since the successor task
started early. Remove the link and total slack for the predecessor task
will suddenly go positive. In that case you need to find a new, valid
successor to that task. In my opinion, ALL tasks in a plan must have a
successor - otherwise why are they being done?

Hope this helps.
John
Project MVP