What is Meant by "CPM Schedule Levels"

What is Meant by "CPM Schedule Levels"

Which CPM Schedule Levels Have You Mastered?

Or better yet: what CPM level scheduler are you? Perhaps like myself – you never considered this before. Do CPM schedules levels even matter?

Many schedulers have heard of CPM schedule levels but not bothered to learn their specific meaning (if any) or its etymology – because the term is used so infrequently, buried deep in schedule specifications, but moreso, for lack of clarity in terms of definition. The concept of eleven distinct schedule levels of detail belongs to the AACE*, who describe each level as having increasing levels of detail, most recently, in 2010.

“These CPM schedule levels go up to eleven. Why not just make make ten more detailed?

If used at all, the concept of ‘CPM schedule levels’ is frequently misconstrued: I recently was tasked with preparing a CPM schedule for a six year treatment facility. The planning engineers requested a Level I schedule, “with all the bells and whistles” … I responded that we needed at least twelve-weeks lead, at which they were aghast. When I explained that it was more likely a proper Level I first, and Level V last, it started to dawn on them.

Abstract as they are to the lay-person, I find that the CPM Schedule Levels have corollaries in practice that could be metricized: i.e., schedulers can hold skill at any Level between 0-4. Insofar as “4-x,” definition serves little purpose, as AACE doesn’t bother to distinguish one from the other either. Such parameters could serve as better guidelines to a given scheduler’s abilities than their puny PSP exam.

Levels of Detail May be Thought of as One Metric of Ability

But what if instead, the CPM schedule levels were somehow used as way of metricizing various schedulers abilities?

My Revised Hierarchy of CPM Schedule Levels, with AACE’s corresponding description

Level 0: Clueless Emperor’s, urban planning tinkerers, project executives, capital construction officers plot these in Powerpoint, Excel, or some non-project logic driven program, and tape them behind the wall of their desk, where they ultimately remain untouched.

AACE: (this) is the total project and in effect is a single bar spanning the project time from start to finish. Functionally there is very little practical application for a schedule that is only a single bar other than to represent an element of a project or program timeline. Level zero schedules normally will include the project or program major milestones and bars indicating key scope.

Gotta love any scale with a Level ‘0’ … frankly, I’d be pleased enough if I received credible data at this level. Level 0 is not meant to be ‘ballpark.’ Exec leaders should be able to dispense certified information.  Level 0 schedules are seldom generated by CPM schedulers; however, their durations and milestones should be informed by industry professionals. In other words, it’s OK to draft at Level 0, provided it is not a mere educated guess.

Level I: general contractors and construction managers often generate Level I schedules from in-house, until the responsibility is taken over by a consultant. These tend not to be very sophisticated, over detailed, and they aren’t meant to be. However; if they needed to be, they would challenge most GC/CM inhouse schedulers, as these entities traditionally don’t invest in CPM schedulers.

AACE: (this) represents the schedule for the project by its major components. For example, a schedule for a process plant may be divided into process area, storage and handling area, services, site areas, and utilities. A Level 1 schedule is normally displayed as a Gantt or bar chart and may include key milestones.

It may or may not be a GANTT chart. If it is, it probably uses constraints and hard-dates.

Level II: general contractors using de facto project managers cum schedulers make up some three-quarters of all builder schedules. These come in all flavors – but most use Microsoft Project, which is rather ill-suited to the building industry, to limited operability past the baseline.

AACE: Each schedule component is further subdivided for Level 2. For example, utility systems are further subdivided into water, electrical, gas, storm drainage and sanitary systems, etc. In most cases Level 2 schedules can only be shown as a bar chart although key constraints may also be displayed. Milestones are normally included.

Level II can still be created in-house, but it requires a little more CPM bandwidth than the typical project manager has (not a crack against any PM – CPM is not their bailiwick, and they are not trained in it.) The scheduler will likely be someone who knows P6 on a rudimentary level, but with building industry knowledge.

Level III: must have a bona-fide critical path. Builders know this by intuition. Book schedulers, or those with ‘certifications’ but little or no industry or field experience to go with them, do not have this sense. “Builder schedulers,” as I like to call them, always know. In fact, they know not only the critical path, but the next several multiple float-paths as a benefit of boots on the ground, not office carpeting.

AACE: The first level that a meaningful** critical path network can be displayed and the CPM schedule can be used to monitor and manage (control) the overall project work. Level 3 is a good level for the overall project control schedule since it is neither too summarized nor too detailed.

Level III seems like it’s still not asking that much, but you’d be surprised at how many struggle, especially when the schedule turns out to be unserviceable before the first update.

Level IV -X, the highest level, should include all of the activities, down to the nitty-gritty in the trenches. This means ‘boots on the ground is an imperatives; and no bookworms. This stripe of scheduler

AACE: The level of schedule subdivision continues to whatever is appropriate detail for the user. When operating at more detailed levels, the planners generally work with segments of the total schedule. Often the project “rolling schedule” includes a “look‐ahead” period of time (30–180 days) and a “look‐back” at recent completed work periods.

Thus does AACE address Schedule Levels in broadstruck at the expense of defining levels of detail and operability for Levels IV – X. For instance, what differentiates a Level 4 scheduler, from say a Level 8 scheduler?


*AACE® International Recommended Practice No. 37R‐06, SCHEDULE LEVELS OF DETAIL – AS APPLIED IN ENGINEERING, PROCUREMENT AND CONSTRUCTION, TCM Framework: 7.2 – Schedule Planning and Development, Rev. March 20, 2010

**(my italics)