What are the known problems with the Critical Path Method?

Question

I was searching online for a tool which would allow me to take my PERT chart and auto generate a Critical Path Method diagram. However, I was not able to find any google sheets or excel sheets which provided this functionality, instead, they mostly offered to generate GANT charts.

All articles I found about CPM charts explained how to do it by hand.

This led me to wonder if CPM is still used/advocated today, or if it is only of historical interest. Are there known issues with it which would make tooling for it unpopular?

Answer 1

If you do not know or understand your critical path in your schedule, then you are not managing your schedule. I have not seen anything else take its place so, as far as I know, CPM is still a relevant and valuable tool for non agile projects. Perhaps CPM can be applied to agile, too, but I am not sure how.

I believe MS Project will color code the network diagram in red for those packages that fall on the critical path. I do not use this feature as the table format is adequate for my analysis, so I cannot explain how to do it.

All this said, critical path management is 100% dependent upon a proper schedule build. We make all kinds of scheduling mistakes in the tool that disallows it to calculate the critical path correctly, and can provide inaccurate indices. Not only this, but I still find so called seasoned practitioners who continue to mistake the critical path with important tasks.

Answer 2

AFAIK, the leading alternative Critical Chain Method, which is no simpler to calculate, and I'm not sure that I would really advance it as a full altnerative - it is a different way of managing the critical path.

From memory, CCM perceives slack as a project level entity, rather than as an attribute of a work package - all slack is tracked at the end, and any work product that runs over can draw from project slack. This leads to teams being more honest about their pessimistic estimates.

I don't think it is really possible to have an alternative to CP; that would be like having an alternative to prime factorization, or an alternative to mass or density. All projects have a critical path whether you calculate or not. Some project managers many not use the CP to manage the project, but it is there, controlling the probability that the project will run over.

Microsoft project will automatically calculate Critical Path - I think it would be very helpful if other answers could reference the ability of other software packages to automatically calculate CP.