CPM Analysis
Hi all,
I have been looking for resources on reading and interpreting a CPM schedule that looks like the attached diagram (from AHPP edt. 15, ch 10). I understand the logic of the CPM however, none of the resources I have, explains which path in this diagram is the CPM path (it is hard to tell if there is a thicker line or darker color signifying), what different shapes next to each task means, how a delay would affect close-out date etc.
I think a practice question giving this scheduling and asking when would the close out day be if procurement is delayed by 5 days. And on that note- do these durations on the cpm only account for business days or all 7 days of the week? I hope a master on the subject would shed some light on this subject. Thanks,
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Pelin & Joanne,
The shapes:
- Diamonds in the summary/schedule signify milestones (usually these are significant events like receiving approvals and substantial completion as you can see above)
- The "pointy bars" (for a lack of better term?) above a grouping of events indicate the total time for that phase (i.e. Construction is shown spanning from May 30 - Aug 6th given the info in the schedule)
- The rectangles just depict the duration of a single event (not whole phase)...sorry this is probably obvious but doesn't hurt to illuminate :)
The overall critical path is shown graphically with a single "pointy bar" at the top that spans from Sept 17 2012 to Sept 11 2014 as it's taking into consideration every single critical path.
As for your hypothetical question about if Procurement was delayed (and its effect), I would just look to see if there's an immediate dependency (shown in a line with an arrow to a bar immediately following the day after it's completion) and see how it would push that whole grouping. However, I'm not particularly seeing that for Procurement in this chart as I am with the dependency shown between the end of Construction Documents and the Estimate for GMP, for example.
I think they are showing bolder lines/arrows to indicate dependancies for certain things and the lighter line may indicate general linking (but maybe not immediate dependency?).
My understanding is the the CPM is based on working days (5), not 7 week days when the overall time required for an event is initially plugged in.
Hope that helps!
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