Longest path - No activties on layout

James,

I no longer have P3 but understand P3 longest path functionality differs from P6, therefore my first question would be to verify you are using P3 as this is a P3 forum.

My second question would be, is the project part of a project group and you are looking for the longest path while detached?

My third question would be, are you using resource leveling/smoothing as it might be that longest path is driven by resource constraints, therefore it is non-continuous if by logic only and perhaps your software cannot see resource dependencies. Keep in mind that P3 longest path is a fix to show continuous path when using different calendars, not sure about when resource leveling moves the path. If using automatic resources leveling, toggle it off, run again schedule without resource leveling and run the filter, this might tell you about the cause but will not necessarily provide you with the cure.

Best regards,
Rafael

Thanks for the direction:

I looked under options and someone (who is in big trouble with me right now) changed the "Calculate total float as" start float, instead of most critical. Once i did that, it worked.

Thanks again for the idea where to look.

James B.

James,

I always believed that Start Float should be called Start Float and Finish Float should be called Finish Float, especially when your software accepts non continuous PDM calculations under activity splitting. If both can have different values then show both and use different names, being ambivalent is wrong.

You need to know both. Perhaps your friend unknowingly made the right choice for his need. In any case blame your software supplier for being so ambivalent. Longest path should not be dependent upon your selection of float definition; anyway, saving one database field at such expense makes no sense to me.

Finally, be skeptical about float, especially resource critical float, even when your software can display the correct value as resource dependencies can change as the schedule moves. Use float as a guide but keep in mind there is nothing like what-if analysis before making critical decisions as computer time is cheap today.

Best Regards,
Rafael

James,

Changing the definition of which float value to use should have nothing what-so-ever to do with determining the P3 function called, “longest path.” It would have a bearing on determining which activities were critical if your definition of critical was set to use Total Float but this is another issue entirely. The P6 longest path function is admittedly more ‘squirrely’ but as this is a P3 forum so I must assume that you are talking about the P3 longest path.

P3 Longest path uses the CPM’s forward pass function and then a ‘back tracing’ function following forward pass controlling relationships. There is no backward pass used with longest path and thus, no instance of Total Float (calculated by subtracting forward pass early dates from backward pass late dates.) It will make no difference to the longest path which definition of Total Float you use.

If you were using the term, longest path to mean critical path using a Total Float definition, then you are mixing two very separate P3 functions. I hope that this helps. Good luck!