Negative Lag

Each relationship in a plan has a meaning.

FS refers to a Finish to Start relationship which states that a process needs to be completed before another can begin. By putting in a negative lag. what this means is that a process can only begin 3 days before the previous will complete.

If that is what you wish to express, then yes it is possible to use such a relationship. However this is generally not agreeable to most planners as the negative lag will have an impact on your critical path.

If however the relationship you want to express is a parallel one, which means that both actives can be run concurrently, then it would be more preferable to use a Start to Start (SS) or a Finish to Finish (FF) relationship with positive lag.

You must use  SS and (+) Log, (-) Lag can affect your critical activity

but if i use FS Zero lag also affect the critical activities and consultant accept to use FS zero lag and not accept to use FS with negative lag is it correct ?

It is rare that FS (or indeed any relationship type) with neagtive lag is a good idea.

Please desribe the activities involved and the reason you want to use negative lag, and we can advise the correct relationships.

Cheers,

G

Hi,

Do not ever use negative lag. Experiences will prove the disadvantage.

If the concern is regarding a requirement to have an activity occuring X days before the completion of another, try applying the primary constraint "as late as possible" to the activity with FS(X) lag to the successor activity

If your completion date moves, (earlier or later) the Meeting Notification activity will move correspondingly.

This would be preferable to a FS negative lag.