Can a TF be greater than the duration of the project

Hi Richu

In most forms of software the total float is measured from the last activity in the chain with an outgoing link to the end of the last activity in the programme.

Therefore it is not possible to have more float than the total contract period.

The situation can be created artificially if you have a milestone hanging out after the last activity with no incoming links.

Best regards

Mike Testro

Yes you can, and it’s a bit silly, so I had to check, but it does kind of make sense.

Check the ’Project must finish by’ date. If this date is later than the early finish of the project, all of the activities will carry float. An early deliverable with no successors until the back end of the job could, in theory, have a Total Float in excess of the Total Duration of the job.

i.e.

Project A has a ’Must finish by’ of Day 500.

The total duration as scheduled is 300days.

As this finish is 200days early, every activity has a TF of at least 200days

The Frontage Sign can be completed by day 20, but is not required until day 270. The TF on the Frontage Sign therefore is (200 + (270-20)) 450 days - far in excess of the O.D. of the Project.

So, yes, it is possible.


But it’s silly, and you want to have another look at your Project dates and your logic.

Richu
If you consider the algorithm to calculate float, the calendar is essential. If you default calendar is e.g. 5-days a week with 8 hours each and the project’s duration is 600 days. Now you have an activity in an early stage just related to the project’s end based e.g. on a calendar with 6 work days a week. The float will be calculated as from the project’s end and on basis of the activity’s calendar - about 700 days.

Recently main German EPC-Contractors had a meeting with Primavera and as this item is rather difficult to explain to management, we asked Primavera, to add an item where the float is calculated based on the project’s calendar.

I assume that other software for scheduling has the same problem.

Regards
Dieter