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Zero float activity - to be in Longest Path

4 replies [Last post]
Haresh Jayanth
User offline. Last seen 2 years 1 week ago. Offline
Joined: 24 Aug 2006
Posts: 219

I have an activity showing Zero float, but not in longest path, what i have to do to make this activity in the longest path without generating a negative float.

Kindly help out.


Haresh Jayanth


Zoltan Palffy
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Joined: 13 Jul 2009
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thats not true and activity with zero float or does not have to be the critical path or the longest path. It is the one with the least amount of float which also can be negative.

do 3 things

first go to edit users preference and click on time units tab and for the durations format make the decimal places 2.

second go to Projects and make sure that your project is highlighted click on the setting tab at the bottom under Define critical Activities make sure that the total float less than or equal to in checked and on the right make sure the value is 0.00

third select tools schedule then options 3/4 way down the page where it says Define Critical activities total float less than or equal to make sure that is checked and the value is 0.00


Chethan MS
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Joined: 20 Apr 2014
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The activities with zero duration maybe or may not be on the longest path, one of the reason could be that the activities with zero float will be having some positive float in the decimal places, if it doesn't work set the crtitical path to 0 and then filter for the critical path. Hope it works. cheers.

Rodel Marasigan
User offline. Last seen 39 weeks 12 hours ago. Offline
Joined: 25 Oct 2006
Posts: 1516
Not all critical activities lie on Longest Path. Below are some causes of zero float or critical activities:
1) Activity or activity path is constrained.
2) You created a multiple critical path.
3) Must finish date is define.
4) Activity path lies on open end and define as critical.
5) Activities lie on critical path but non-driving activities.
6) Lies on longest path.
Samer Zawaydeh
User offline. Last seen 1 year 4 hours ago. Offline
Joined: 3 Aug 2008
Posts: 1664
Dear Haresh,

Back Engineeering your Schedule might not be constructable. If you have followed the Activity/Sequencing/Resources, then your longest path should be correct and you do not need that activity to be on the MOST critical path.

So my advice would be to check the constructability of the Schedule again.

With kind regards,