Critical Path Myth, Part 3: Conclusion? Delusion!


Blog Series Abstract

The widespread faith in the Critical Path Concept is not justified by the facts. Still, those with a vested interest in their projects finishing timely continue to support the Critical Path Concept and embrace recommended practices that they are told will lead to more successful projects. This three-part blog series is intended to shed light on the Great Delusion under which most Project Management stakeholders unknowingly suffer.

Myself hardly naïve, I fully expect disagreement with what is written in these three blogs. The resistance expected from Critical Path Concept proponents is both understandable and anticipated. I am comforted by a saying in the Air Force: “if you’re drawing flak, you must be over the target.” I remain hopeful that the discussions and debates that this Blog Series is certain to provoke will nonetheless facilitate the kind of open, honest, and informed dialogue needed to at last turn around the ship upon which we all sail together. The truth shall set us free.

About Critical Path Myth, Part 3: Conclusion? Delusion!

Part 1 and Part 2 have informed us that a great injustice has been perpetrated on those who have the most to lose, should their Projects miss important temporal goals. Unwarranted faith has been placed on a Critical Path Concept that is fraught with problems, in theory and in practice. There is only one Conclusion to be reached about the state of present-day Construction Project Time Management: Project Stakeholders are unwittingly suffering under a great Delusion. They think that the Critical Path Concept works, when in reality it faces many challenges. Worse still, empirical evidence suggests that many of the policies of Construction Executives may well be further eroding Schedule Credibility, thus making effective Project Time Management even less likely!

In Part 3, we will acknowledge that most Construction Project stakeholders are mostly unaware of the many compounding shortcomings contained within so many recommended Project Management practices that have the Critical Path Concept somewhere at their core. With a lump in our throats we come to realize — much to our surprise and chagrin — that we, as Construction Executives, may actually be dealing our Projects the greatest blows by way of policies and contractual requirements that drive the final nails into the Project Time Management coffin. But, so as to wrap up on a positive note the blog concludes with a few simple changes that Owners can rather make that could dramatically improve the temporal outcome of their construction projects.

Recap of Parts 1 and 2

In Part 1, Confusion and Illusion, we learned that the Critical Path Concept is fraught with uncertainty. As amply discussed, it suffers widespread terminological deficits, surprising disagreement over key computed values, and even confusion within the very context of the Critical Path Concept.

In Part 2, Diffusion and Infusion, we began to wonder how a Concept so fraught with limitations would be a chosen as the foundation of a broad Project Management ideology. But where Part 1 examined the raw fundamentals of the Critical Path Concept, Part 2 took a more analytical and substantive review of the Concept’s implications. In a short discussion about Schedule Data Credibility, we were told that Schedule Credibility improves over time. In the inverse, a Schedule is least credible at its outset. We learned that Performance Data, already highly speculative, will degrade after about ten weeks and that a Schedule’s level of detail needs to be correlated with the length of the project that it seeks to model.

Next,  we entered a meaty study of the real meaning of Total Float and Critical Path. We were enlightened to learn that Total Float measures the gap between two essentially irrelevant and temporal extremes. Earliest Dates represent extremely unlikely performance, whereas Latest Dates represent an extremely irresponsible Project Management strategy. Removing any rose-colored spectacles we might be wearing, Part 2 reminds us that a Baseline Schedule with a Critical Path bearing zero Total Float is about as prudent as starting a business with no money in the bank. Yet, that is precisely what many Contracts require of the Contractor: to submit a Schedule shows Zero Total Float along the Critical Path!

Despite all of the shortcomings discussed in Parts 1 and 2, the Project Management community continues to sing the praises of the Critical Path Concept. They do so, even as they continue to argue with one another over a wide range of technical issues.  That these issues have not been resolved long before now may well explain why there is such inconsistency and confusion in Project Time Management products and services. [Note: If you have not read Part 1 and Part 2, I strongly encourage you to do so.  The discussions we will have over the next two weeks will surely touch on contents of the both other blog parts.]

Counter-Productive Project Management Policies & Practices

Here in Part 3, we will take a candid and sober look at some of the many ways that Construction Executives only make matters far worse, by the policies they adopt, the rules they impose, and the expectations that harbor. It is my genuine hope that, by laying all of this out on the table, we can have an honest and productive discussion about ways that each Project Time Management stakeholder can change the way they do what they do, for the betterment of the Project. We all have a hand in the timely outcome of the Project. This set of three blogs is meant to throw bright floodlights on some of the more egregious and damaging practices, policies, and actions.

How the Critical Path Concept Negatively Affects Project Management

Some of what you are about to read under this heading are points that I seriously doubt you have heard or read anywhere else. I know that I have scoured the Internet and come up dry, in my search for comparable examination. At a very minimum, I hope the following will give you something to think about.  Let’s get started:

The Critical Path Concept Over-Simplifies Project Time Management

For starters, it seems to me that Project Management literature (and even doctrine) tends to reduce Project Time Management to whatever fits neatly within the Critical Path Concept. The mantra of generations has been, “Plan your work, and work your plan.” It is as if Project Execution (and, inclusive of that, Project Time Management) boils down to simply creating very good Project Schedule, and then simply “following it.”  But the intersection of theory and practice is in how the Schedule is maintained and used, from one performance/reporting period to the next.

The Schedule is referenced, work is executed, performance is measured, Key Performance Indicators are compiled, reports are distributed, explanations are sought, “corrective” actions are crafted and implemented and … then the whole cycle starts all over again. Most prominent among the Key Performance Indicators are two familiar values: Total Float and the Critical Path. But even Critical Path is secondary to Total Float, when it comes to convenience of measuring Project performance. As Total Float shrinks, Management concern grows; as Total Float inflates, concern is relaxed. In a very practical sense, the current ideology of Project Managements seems to be that … Project Time Management amounts to Total Float Management.

“Management By the Numbers”

I use this expression somewhat sarcastically.  For it seems to me that far too many of today’s Project Managers put greater focus on how their “numbers look” than how the Project is actually proceeding. I blame Construction Executives for this, to whatever extent it is true.  After all, if Owners and General Managers didn’t put such importance of these Key Performance Indicators, maybe the Paper Project would be less important than the Physical Project.

Nowadays, Every Project is Actually Two Projects

And that brings me to my first boat-rocking declaration: as practiced today, every construction project is actually two projects: the Paper Project, and the Physical Project. And we can draw some important conclusions from this revelation:

  • Each “Project” has its own Project Manager.
  • Each “Project” has its own goals and objectives
  • Each “Project” should have its own management tools and resources
  • Each “Project” has its own customer

Let’s take this all in.  As we do, think of the Contractor’s Site Superintendent as the “project manager” for the Physical Project. Now think of the traditional Contractor’s titled Project Manager as the “project manager” for the Paper Project. The Site Superintendent is clear about his goals and objectives: to complete the Physical Project successfully, in compliance with the Contract Documents. This means completing it on time, within budget, and with expected quality and safety.  He has one prime customer: the Construction Project Owner.

He doesn’t give a damn about the Contractor’s Home Office and all of the political, fiscal, and contractual BS. The titled Project Manager, however, lives and dies by “the numbers.” His Project is performed on paper. After all, to a very real extent, that is where money will be made or lost, time will be reported as gained or lost, time extensions will be sought and secured, claims will be asserted and won, savings and cost containment will be achieved. It’s all about the Numbers!  The Paper Project Manager has two customers: the Construction Project Owner and Home Office Senior Management.

Both Projects (and Managers) Use the Same Schedule!

Now, here’s the “rub,” to borrow a word from Shakespeare: both Projects use the same Project Schedule. And that makes it the rope in a terribly violent tug-of-war. Actually, that are several ropes passing through the Project Schedule, stretching it into such great tension that it might surely break at any moment.

  • As just noted, the Paper Project Manager and the Physical Project Manager tug on the Schedule, from opposite ends. One wants it more detailed, the other more general. One wants it more flexible, fluid, and responsive. The other wants it more stable, consistent, and controlling.
  • The Owner and the Contractor also tug on a rope that passes through the Schedule. The Owner wants the Schedule to lock the Contractor down, and to use it to monitor the Contractor. The Contractor wants the Schedule to have “wiggle room,” in order to support its planned claims time extensions and adjustments in reaction to scope changes.
  • The Design Professionals grab the rope before the Contractor has even arrived on the scene. They consume a disproportionate amount of the available Project Length (a combination of design, procurement, and construction phases).  When the Contractor comes aboard, he finds the flag well past the center line!

I could go on, but you get the point. These two “Projects” are in a constant state of conflict with one another. And that explains why the Project Manager and Site Superintendent do not always see things the same way, why Owner and Contractor impose important yet often-opposing requirements on the content and use of the Schedule, and why Contractors have a general dislike for (or at least irritation with) Design Professionals who, as they see it, do not seem to view “reality” the same way that they (the Contractor) do. Caught in the middle is the Project Schedule which, let us not forget, is the central gear in the Project Execution machine. If the Schedule becomes dysfunctional, then you can kiss timely completion goodbye.

How the Critical Path Concept Negatively Affects Project Execution

Before going into the discussion we are about to have concerning how pursuit and protection of the Critical Path can, and often does, actually extend the length of a Project, it might be helpful to those who are not very familiar with the Critical Path Concept to get a quick primer.

Roof Over a City: How the Longest Path Determines the Shortest Project Length

Imagine being asked to construct a roof over Manhattan. What is the lowest (in elevation) that that roof could be? Answer: no lower than the tallest building. Right? Before the terrorists attack on the World Trade Center on September 11, 2001, these tallest buildings in Manhattan topped out at 1,727 feet. So, that is the lowest that the roof could have been at that time. But after the destruction of the Twin Towers, suddenly the Empire State Building was now the tallest building, at 1,454 feet.  You get the idea.

And we can form a statement that, at first, seems a little counter-intuitive: the lowest that the roof can be is determined by the highest building. Well, if you turn the city skyline on its side, and substitute “roof” for Project Completion, and building heights for Activity Path lengths, you get the explanation for how a Critical Path determines a Project Completion. If every building represents an Activity Path, then the tallest building represents the “critical” path. And so, we get this statement: the shortest Project Length is determined by the longest Activity Path — the critical path.

But is our example maybe a little too simplistic? Aren’t we assuming that all city building stand on a level downtown base? If they do, then it would remain true that the tallest building reaches the highest point in the air. But what if we were talking San Francisco, not Manhattan? There, the tallest building is the TransAmerica Pyramid, which stands 850 feet in the air. Except … it is based at only four feet above sea level. Now, also within the city limits are the Twin Peaks, which top out at 922 feet above sea level. Suppose we were to construct a short, one-story house on the top of one of the peaks, with its roof only 28 feet from the ground. This would put the roof’s highest point at 950 above sea level.

Meanwhile, the top of the towering Trans Am Building is actually lower, at 854 feet. What we see from this example is that it is not actually the tallness of the building that matters to our roof’s lowest elevation … it is the ultimate height that each building reaches. Likewise, in a Project Schedule, not all Activity Paths begin at the start of the Schedule or extend all the way to the end of the Schedule. If they all did, then the Manhattan scenario would be a useful analogy. But, in practice, Activity Paths can start anywhere along the length of the Schedule.  And so, it is possible that the Activity Path that determines the earliest that the Project can finish may not be the longest Path.

Manage to the Critical Path

Perhaps now you might be better informed to understand the thinking behind the principle advanced by the advocates of the Critical Path Concept. For if you want to finish your Project as soon as possible, then make sure you do not extend the Critical Path. That would be like adding floors to the building that already reaches the highest into the air. In fact, the opposite is sometimes asserted (although, it is factually incorrect), that for every day that you shorten the Critical Path, you pick up a day on the Project Completion. You get the idea; according to Critical Path Concept dogma, it is all about managing to the Critical Path. And it certainly seems to make a lot of sense, and for over five decades this has been the guiding principle behind the Critical Path Method of managing projects:  manage to the Critical Path.

The Lane Hopping Effect

But I am here to tell you something you have likely never heard before. Managing to the Critical Path may quite possibly extending the length of your projects! The explanation of this phenomenon is what I call the “Lane Hopping Effect, and it works this way. Traffic engineers are familiar with a pattern where drivers, frustrated with being caught in the grip of bumper-to-bumper rush-hour traffic, upon seeing an adjacent lane seemingly flowing more freely, all simultaneously jump into the “fast-moving” lane. Within a matter of seconds, the previously fast-moving lane slows to a crawl, and the lane which the cars had just abandoned suddenly becomes the fast-moving lane. They call this oddity, “filling one’s own vacuum.”

ICS-Research has found that the same thing happens on Projects that are managed to the Critical Path. Because of the disproportionate emphasis placed on Total Float, the natural and common tendency of Project Managers is to favor Critical Path activities at the expense of non-critical activities. This predilection is fueled by “practice standards” that establish the safeguarding of the Critical Path as a “standard of care,” such that not to do so might be argued as professional negligence. Of course, when an excess of resources are directed toward a “critical” Path, other Paths from which the resources were drawn can suddenly become more “critical,” even as the initially-critical Path turns non-critical.

In other words, by managing the Project through systematic responses to dropping Total Float values, the Project Execution team is constantly chasing its own tail. You might be interested to learn that ICS-Research studies show, beyond a margin of error, that managing to the Critical Path is often counter-productive. Experiments conducted on Schedules of completed Projects proved that, had the same overall level of effort been applied evenly to all available activities (rather than primarily to critical and near-critical Activities), the Project would have finished sooner than it did by managing to the Critical Path.

The “Fill the Buckets of Water” Problem

The Critical Path Concept also makes another assumption that is not substantiated by the experience on most Construction Projects. It assumes that there is enough energy to complete the Project in the allotted time. Now you may think that a Baseline Schedule – which must show a Project Completion date equal to the Contract Completion Date in order to gain Owner approval  – confirms that the original Schedule surely anticipated sufficient energy. But you might be wrong. To explain, let me present a simple example. Assume that we are given 60 ten-gallon buckets and told to fill them with water from a tap. Assume that the maximum water pressure out of the tap is 60 gallons per hour. Clearly, it will take 10 hours to fill all 60 buckets. Now suppose that we sign a Contract which obligates us to fill all 60 ten-gallon buckets in just EIGHT hours. Given the above “facts,” we can easily see that it cannot be done., given the maximum water pressure out of the tap, right?

Now let’s see how we might be able to trick ourselves (and others?) into thinking that it can be done. It’s really quite simple.

  • First, we divide the 60 buckets into six groups, which we label Group A through Group F. Each Bucket Group contains ten buckets.
  • We earmark Group A as our  “sampling” subset of buckets. We will use statistics concerning this Sample Group’s progress to interpolate the presumed progress of the other five Groups.
  • Next, we buy a six-way splitter and six garden hoses. We connect one end of each hose to the splitter, and place the other end of each hose into one of the buckets from its Group.
  • Finally, as a basis for later interpolating the statistics associated with our progress on Group A, we make the assumption that all Groups will be filled at the same time.

Now, since everything is equal in our example, the progress within each Group is equivalent and the interpolation from Group A is valid. The maximum flow rate was given at 60 gallons per hour. That means that 10 gallons of water will be flowing out of each hose, per hour.  And that means that each hose can fill one bucket each hour. We conclude that each Group will require ten hours to fill its ten buckets. But we still have that pesky Contract requirement, to completely fill all  60 buckets in only eight hours, not ten hours.  So here is how we game the system. We commandeer Hose B for fifteen minutes of each hour! As we fill the Group A buckets at this higher flow rate, it appears that we will be able to fill Group A’s ten buckets in eight hours!

And since we are still telling the world that, “as Group A goes, all groups go,” the impression we are giving is that all is well. But is it? Remember that we were told that the tap had a maximum capacity of 60 gallons per hour. And we are consuming 12½ gallons per hour, just for Group A. That leaves the remaining 47½ gallons per hour to be shared by five Groups, equally. I’ll spare you the math.  Bottom Line: those other five Groups will now take ten hours and 32 minutes for their buckets to get filled. So — not only will we not complete the Project in the required eight hours, we see that by diverting resources, what should have taken ten hours is now expected to take 10 1/2 hours!

What we learn from this simple Fill the Water Buckets example is that a sampling set only tells us about the whole if the sampling set is treated the same as the whole. But when the Sampling Set is given preferential treatment over the general population, one can no longer draw conclusions about the whole from the performance of the sampling. Now let’s go back to the Lane Hopping Effect, where I stated earlier that when we give higher priority to Critical Path activities, we can actually extend Project length. I call this “energy spillage.”

Back to our Bucket metaphor, each time we swing the Hose B away from its bucket and over to the Group A bucket, some water spills on the ground! And we are going to borrow the hose eight times! Well, the same thing happens to limited resources on a Project. The more we bounce them around, the less efficient we are across the board. And on a Project where it will take maximum resources to meet an end date, resource spillage usually means schedule slippage. Interestingly, when I  was consulting the Arizona DOT, those traffic engineers told me that their studies had found that (a) all of that Lane Hopping doesn’t actually gain any advantage for the lane-darting vehicle; they still end up in the same place at the same time. And, (b) all they accomplish is unnecessarily expended fuel, burned brake pads, and tattered nerves.

An Unwanted Paradigm Shift

Another harmful consequence of the Critical Path Concept has been a destructive shift in attitudes among virtually all parties to the Project. The two key culprits are the Construction Executives and the Project Managers; the rest of the players have been mainly reactionary in their attitude changes. For their part, Owners have expressed distrust in Contractors. This distrust is clearly reflected in the tone and content of their Contracts. Of course this is music in the ears of Project Controls advocates who happen to believe that control of the Project is not only possible, it is essential. (I disagree, on both points.) In response to the Owner’s squeeze play, Contractors have become more defensive and cunning, less trusting and conciliatory.

As we noted earlier, the Project Schedule is the rope in a multi-player tug-of-war.  This explains why each contestant in the battle rushes to implant his own preferred seeds (of future victory) into the unsuspecting Schedule. The Project Executor (the Site Superintendent who, you will recall, is the “project manager” for the Physical Project) is essentially out-gunned. He reluctantly accepts the Schedule that is being crammed down his throat. Inwardly, he resigns to ignoring it as much as possible. The Project Planner or Scheduler practitioner, meanwhile, carries the main burden for Schedule Development, Maintenance. (Adoption and implementation remains the responsibility of the two project Managers – albeit, each for their own separate purposes). Meanwhile, non-Scheduling Project Controls personnel, one step removed from primary responsibility for Schedule Development and Maintenance, nonetheless pursue their assigned interests: cost control, quality control, risk management, resource management, etc.

The Critical Path Concept, in Practice: A Reactionary Model

And all of this plays out against the backdrop of those pesky “Numbers.” This is how all parties use the Project Schedule, for their respective, different, and often opposing ends. And chief among the facts and figures to be extracted from the Schedule are … Total Float and Critical Path. For the Paper Project Manager Total Float is of primary importance. That’s because Management believes (however, wrongly) that it captures the overall status of the Project in a single numerical value. Construction Executives have been told (again, wrongly) that by monitoring the Total Float of key milestones, one can get a reliable and useful reading on the likelihood of the Project achieving its temporal goals.

Managers of Paper Project well appreciate the significance of Total Float. And so they place it first and foremost among their Key Statistics. Schedulers have been schooled in producing the three main CPM Reports: sorted by Activity Identifier, by Early Start, and by Total Float. The first one is used almost exclusively by the Schedulers, themselves.  The Early Start Report is the first choice of the Physical Project Manager. And the Total Float Report is what the Paper Project Manager flips through each time a new one comes out.

And the process is almost always the same. The Total Float Report (also known as a Criticality Report) is sorted by Total Float with the lowest or least Total Float at the top of page 1.  It is Standard Operating Procedure for the Paper Project Manager to glide his finger down the right-most column of the first page, hoping to see any negative Total Float numbers gradually fade into zero, and then turn to positive Total Float. “Damn!” he mumbles to himself, as he flips the page and continues to see negative Total Float on the second page. And if the negative Total Float eventually disappears somewhere on the third page, the Project Manager sighs slightly, thinking to himself, “We have our work cut out for us.” And for the next few weeks, until the next set of Schedule Reports come out, he will be focusing attention on, and diverting resources to, those negative Total Float Activities.

And what happens to all of those Activities on page 4 and beyond – the ones with the positive Total Float? Well, they are essentially ignored. It’s the old, “too busy extinguishing fires to take a notice of new smoke” syndrome.  I hope you recognize this scenario for what it truly is: reactionary. And the Scheduling Community, with its trained Schedulers and recommended practices, are right there to fuel the insanity. Just consider how “seasoned” Schedulers interpret a Total Float reading of -8 days. “The Project Completion activity had zero Total Float in the Baseline Schedule. This shifted to TF -2 in the first month, TF -4 in the second month, TF -6 in the third month, and now TF -8 here at the end of the fourth month.  This means that, as of right now, we predict completing the Project eight days late.”

“Eight” days late? Really?  How about 36 days late? Why do I say this? Because this is an 18-month project and we seem to be losing two days each month. My point is that the typical interpretation of Total Float often disregards trending data. But that’s not how it always was. Back when I was a newbie Scheduler (in the 1970s), trending extrapolations were commonplace. Over the years, however, attitude changed at the Management level, and new directives were given to the Project Scheduler. Bad news was swept under the rug. Remember: Project Management means Total Float Management. And the Subcontractors have gotten the memo, too! They have learned how to interpret that right-most column. If their Activities bear two-digit positive Total Float, just try convincing them that their “immediate performance is critical to the Project’s temporal goals!”  They can read, and they aren’t buying it. Their sense of urgency has been dimmed.

Infusion: Additional Uses for the Project Schedule

So far in this third blog, everything I have written about relates back to the Project Schedule in its primary role as a Project Time Management tool.  What I am about to tell you is that others — with no real concern for the factors that impede timely Project completion — also have dibs on the Project Schedule and its all-important temporal data. The simple message to Construction Executives reading this blog is that each of these other uses has only served to further erode the Schedule. And since the Project Schedule is not just the main temporal tool, but the only temporal tool used by the Project Executor (Site Superintendent), as the Project Schedule gradually loses its credibility and reliability, there goes Project Management’s innate ability to self-manage as effectively as possible. In the end, the Project suffers. As you read on, please make a mental note of how each one of these additional uses for the Project Schedule puts added pressure on the Paper Project Manager to manage to the Critical Path.

Change Orders and Time Extensions

Virtually all Construction Projects incur changes, and each change presents an opportunity for the Contractor and Owner to renegotiate the Contract. Up for discussion and agreement are increases or decreases in cost and time commitments. In this blog we are concerned with the latter. It has become normal practice for the Contractor to include in its Change Order Proposal a side-product known in the Scheduling World as a TIA, or Time Impact Analysis. In a nutshell, here is how it works: the Contractor develops a small sketch of schedule logic (called a “fragnet”) which depicts the added work. This fragnet contains all of the typical elements of a CPM schedule (activities, dependencies, durations, date constraints, etc.), but it only pertains to the work scope of the Change.

Then the fragnet is “placed” within the greater logic of the most recent Schedule Update. Depending on where the fragnet is tied into the Project Schedule, the Total Float of the Schedule’s downstream Activities may be negatively affected. If they cause Total Float of downstream Activity Paths to “go negative,” then the Contractor is justified in asking for a time extension to the overall contract. Obviously, there is an unspoken desire on the part of the Contractor for the TIA to justify a time extension. This, of course, translates into palpable pressure on the Paper Project Manager to “tweak” the fragnet and its placement, at all times with an eye on that all-important Total Float.

Time-Related Claims for Delay and Acceleration

On a larger scale, the same conditions, general processes, and motivations operate behind the scenes, as Contractors and/or Owners assert or defend against claims of delay or acceleration. Once again, the all-important variable is Total Float along with its primary derivative, the Critical Path. Again, immense pressure is placed on the design and maintenance of the Project Schedule, with a trained eye at all times focused on Total Float and Critical Path.

Performance Evaluations

Constructions Executives have overwhelmingly acclaimed the simplicity and clarity of Key Performance Indicators, prime among these being the Total Float and Critical Path values.

  • Management (of both Owners and Contractors) interpret even the slightest changes in Total Float values as possible evidence of Project Management ineffectiveness. Project Managers know this, and since they are the primary source for Schedule Update information, there is a great pressure (if not also, tendency) to withhold certain facts and perhaps embellish others, in an effort to affect the final reports.
  • It is common in most construction contracts to link approval of Progress Payment Applications to Schedule Reports that validate or confirm performance. Percent Complete values, per Activity, aggregate to the amount for which the Contractor can seek compensation.  But those same Percent Complete values are part of the calculations of Early Dates which, you will recall, are the basis for Total Float. Paper Project Managers are forever struggling to find the right balance between justifying the largest Pay App on the one hand, and not skewing the Critical Path away from its most advantageous route (in terms of Change Order TIAs and Delay/Acceleration claims).
  • Even Earned Value Reports, when they signal possibly troubling trends, merely send Paper Project Managers back to the CPM Schedule to determine whether (and, if so, by how much) Total Float Activities are involved in the bad news.

Other Project Controls Uses of the Schedule

Finally, in order for some of these other Project Controls interests to use the Project Schedule for their particular purposes, they sometimes have need to modify how the Project Schedule is constructed or maintained. Two immediate examples of this are Work Breakdown Structure and Cost Accounts. Both typically emanate from the Cost Engineering component of Project Controls. A Work Breakdown Structure is a formal coding system that accompanies the Project Schedule, and organizes the data records within it.

Unfortunately, one of the unavoidable restrictions of a WBS system is that no activity can have (belong to) more than one WBS class. The practical effect of this requirement is that it often drives the schedule into more detail than would otherwise be required for the Schedule to be an effective temporal tool. In fact, this requirement can easily render an otherwise good schedule less than fully effective. Along much the same lines, many Cost Engineering entities employ Cost Accounting practices that mandate that no Activity can belong to more than one Cost Account. Here, too, the net effect is to drive the Schedule into needless and possibly counter-productive detail.

The point of this short subsection is that these “external forces,” so commonly endorsed and sponsored by Executive Management, quite often introduces additional pressures on an already over-stressed Project Schedule. And as the Paper Project Managers struggles to strike the right balances (as described above), these additional restraints only further complicate the assignment.

Contractual Clauses that Handicap, Impede, or Sabotage

This next section ought to raise some eyebrows, for this is where I get specific on how Owners, for the most part unwittingly, can make matters worse than they already are when it comes to achieving effective Project Time Management. While there are many more reasons than just the ones listed here, this short list in meant to give tangible examples of how Owners can unintentionally further handicap, impede, or sabotage their Project’s Time Management efforts :

No Early Completion Clause

Many construction contracts prohibit the Contractor from submitting a Baseline Schedule that shows the Project completing any earlier than the Project Completion Date set in the Contract. Behind this clause is a fear by the Owner that, if the Contractor shows how he could finish earlier, then if during the course of the Project the Owner is responsible for any delays that might deny the Contractor the chance to complete early, the Contractor might be owed a time extension.  Now let me tell you how this clause hurts the Project, although it should be obvious, based on what we discussed earlier.

Suppose the Contract grants 300 days to complete a project, and the Contractor has crafted a Project Execution Strategy that shows completion in 275 days. Such a Schedule would show Total Float of 25 days, right? But when a No Early Completion clause is imposed, the Contractor is forced to artificially elongate the Schedule in order to eliminate the positive Total Float. It is time to recall what we said earlier about what a Critical Path with zero Total Float actually means. It means that, for the duration of the Project, the earliest that any Activity along the Critical Path can be performed is also the latest possible moment that it can be performed! I ask again, as I did before: is this any way to run a Project?  Do you, as a Construction Executive, really want to demand removal of any time cushion from the Project Schedule?

And keep this in mind: schedules become self-fulfilling prophecies. You see, when a Schedule is artificially elongated, the Earliest Dates are deferred until a later time (“pushed out,” “slipped to the right”). But because the Schedule is not just a budget, but instead a key tool for planning future performance, subcontractors actually use the schedule to plan their work. And so, if it the Painter reads that he will not be needed until June, then he may well take another job that wraps up in May. But the Painter was looking at an artificially elongated Schedule, the distorted Schedule mandated by the No Early Completion clause. Without that clause, the Schedule would have shown the Painter starting work 25 days earlier! Supposing actual performance moves at a pace consistent with original, non-padded Schedule, and the Contractor needs the Painter in May .. he now has to pay a premium to get the subcontractor to site “earlier than planned.”

And let’s not overlook two other, counter-productive side effects of a No Early Completion clause. One: it forces the Contractor to hide Total Float. And even though the Contract may also include a prohibition against “Sequestering Float,” this clause necessities just such a practice anyway. Two: it distorts Total Float readings for all Activities in the Schedule, not just the ones residing on the Critical Path. Without getting too technical, the longer the Critical Path is, the greater the Total Float values for non-critical paths. Go back to our Roof Over the City example. If we add floors to the already tallest building in the city, then, for each other building, the distance between the Roof and the building’s top merely increases. The harmful effect of inflated Total Float values (along non-critical paths) is that it increases apathy and cools any sense of urgency among those responsible for performing these “non-critical” activities.

Float Ownership Clause

Perhaps no other clause is more threatening to the temporal goals of a Project than this one, for it is here that the Owner sets the tone for the Project. Unless this clause gives 100% ownership of Total Float to the Contractor then, no matter how it is worded, this clause sets up a Zero Sum Game that no party can win. I am of the strong opinion that Total Float belongs to the Contractor and that the Owner has no ethical right to it. Let me explain how it negatively impacts the Project. When the Owner claims its right to use of available Total Float, the Contractor is forced to hide the Float. And even though the No Float Sequestering Clause may be exist in the Contract, and even if there is not a No Early Completion Clause in the Contract, the Contractor will do whatever he can to preserve as much Total Float as possible for his exclusive use.

Since the Contractor is the one to create the Baseline Schedule, he enjoys the first opportunity to manipulate its content, if he so chooses. [Now there may be Schedulers reading this blog who will voice strong objection to what they perceive as my characterization of Contractors as devious, dishonest, and conspiring folks. They will argue that most are quite honest and decent. I would agree. But there is a stark difference between being dishonest, and gaming the system. And Owners game the system, too. As many Contractors view one-sided, dictatorial Contracts, they silently think, “you fight fire with fire.”

A Few Immediate Suggestions

As stated earlier, there are far more practical suggestions I could make than appear below. These are just a few of the more obvious ones that can be implemented with little fanfare. Still, they will require Construction Executives who have the courage to invoke change and the conviction to make things better.

Require Full-Blown CPM Schedule with Bid Proposal

The concept behind this suggestion is that each bidder would submit a comprehensive, detailed Critical Path Method Schedule with its Bid Proposal. Even though this effort would be “wasted” on all but the winning bidder, the arguments in favor such a requirement are still impressive:

  • For a bidder to construct a credible cost proposal, they need to think through how they will build the project.  And the level of forethought when it comes to Execution Strategy should be no less detailed than the level of contemplation that goes into the cost estimate.  Quantity take-offs go down to the pounds of nails and sheets of drywall.  Why should the Bid Schedule not get down to the single activities?
  • It allows the Owner (or its agents) to really understand how each Bidder envisions performing the work.
  • It allows an apples-to-apples comparison between bidders proposals.
  • It puts credibility behind each Bidder’s promises.  They can promise anything. But a detailed Schedule shows that they have thought it through and really believe what they are promising.

Best of all, though, having a full-blown CPM Schedule before Notice to Proceed means that the Project will start with Schedule in place. This is a big deal, Owners, because empirical evidence shows that 80% of the delays that afflict a Project sink their roots during the first 20% of the Project Length. On an 18-month project, that makes the first two months highly vulnerable to Schedule slippage. Yet this is precisely the same time period when the Project Schedule is still being developed, submitted, and reviewed under the current, traditional model. Most contracts allow the Contractor 30-45 days to submit the Project Schedule, and the Owner (or its agents) is granted another 2-4 weeks to review and approve it.  And if it is not approved, subsequent resubmittals only further delay the adoption and first practical use of the Project Schedule!

Suggested Contractual Changes

Here are a few changes to the Contract boilerplate that can make a huge difference in how well Project Time Management is accomplished on your Projects. It should flow logically enough from the above discussion, to:

  • Grant Contractors 100% ownership of all Total Float.
  • Allow the Contractor to show an Early Completion in its Baseline Schedule, with no penalty to either party for such allowance.
  • Review and Approve the Baseline Schedule only for the following:
    • Consistency with the Bid Proposal Schedule
    • Acceptable resource-loading (e.g., no front-end loading)
    • Presence and proper placement of all contractual milestones
  • Allow Contractors to change the Schedule at will, without requiring prior Owner permission. The only restriction is that major milestones cannot be removed or their requirement dates adjusted.
  • Do not specify expensive, complicated Enterprise-level scheduling software unless the Project involved multiple sub-projects spanning five or more years.

Reduce Dependence on Total Float and Critical Path

Now the following ideas may be a bit further out on the fringe, harder to adopt either easily or immediately. But I mention them to give you something to think and talk about.

  • Allow a Different Method to Perform Time Impact Analysis: For instance, we can use Performance Intensity (a Momentum Management value) to automatically calculate the time extension justified by the Change Order fragnet. No need to worry about placing the fragnet in the Schedule and seeing whether (or, to what extent) it negatively impacts a Critical Path. Instead, by way of arithmetic formula, every Change will generate an adjustment to Contractual Milestones, regardless of whether the changes impact a Critical Path, or not.  If you are interested in this, write to me.
  • Use a Different Method to Evaluate Performance: Here, too, Performance Intensity can be used to speculate on whether and when downstream deadlines will be achieved.  Performance Intensity is actually a far more stable, consistent, and earlier indicator of project performance than traditional Total Float or Earned Value computations.
  • Resolve All Delay/Acceleration Claims as Soon as Possible: As the saying goes, “bad news does not get better with age.” As much as possible, resolve time-relayed disputes as soon as the relevant facts are known.  Use Performance Intensity, instead of Total Float, to quantify time impacts.
  • Track Milestones Outside of the Project Schedule: By reducing the number of Date Constraints imposed on the Schedule, the Total Float values that appear will be more reflective of true Schedule Vulnerability and Resilience.

The advantage of each of these changes in approach is that they take Total Float out of the equation. And if we can eliminate the use of Total Float for anything other prioritizing Project Execution, we can greatly reduce, and possibly even eliminate the need, temptation, or practice of Schedule manipulation. If only the Schedule could be returned to being strictly a Project Time Management tool, it stands to reason that the Project’s temporal goals would more likely be achieved.

Adopt Monitored Paths Ranking System in Lieu of Critical Path

This last suggestion may require more explanation than this blog has space for.  It is already way too long!  If one is interested, there is a free ICS-White Paper at the Continuing Scheducation website.  Basically, the idea is that instead of having this single, theoretical, comparative value called “the Critical Path” that leads to just the Project Completion milestone … we would replace it with the following schema:

  • Ranking System: Instead of a comparative determinant (e.g., longest or least), we would establish a set of constant terms with fixed parameters, much like what are used in medicine or meteorology. Then, every Path in a Schedule would be evaluated and ranked against these fixed parameters.
  • Multiple Paramount Paths: For each downstream milestone, all Paths leading to the milestone would be identified and ranked.
  • Paramount Path: The most influential of all Paths feeding into a milestone would be deemed the Paramount Path.

Conclusion: About This Three-Part Blog Series

For those of you who are critics of the Critical Path Method, a special word: You may be getting giddy inside, thinking that you have found support and camaraderie from someone who has been such an outspoken proponent of the Critical Path Method for so much of his nearly four-decade career. My message to you is this: do not misunderstand me. Re-read these three blogs. For throughout these three blogs, I have been quite careful and selective in my wording. To be sure, I have been openly critical… but not of the Critical Path Method, but rather of what I have purposely called the Critical Path Concept.

Let me be clear: I still believe that the fundamental structures, elements, and mechanisms of CPM are as good of a tool set as we have seen to date in the latest innovations of recent years (including my own … Momentum Management, Cognitive, etc.).  What I am up in arms about is what we do with this potent and brilliant system of formulas, notational symbols, and core processes. My father used to tell my brothers and me, “In life, it is far less important what you do as how you do it. It’s not so much what you say, as how you say it.” That ridiculous argument by the National Rifle Association that “guns don’t kill people, people do” is a rhetorical load of hooey. Hell, guns and bullets absolutely do kill people (and animals). Of course, so do cigarettes, poison Ivy, plutonium, trains and cars, bombs, swords and daggers. Even pillows, water, snowflakes, or marshmallows can be used to snuff out life. My point is that we are remiss if we ignore or dismiss the People behind the Actions, and the Will behind the People.

And nowhere are the endless manifestations of Human Will more evident, or more potent, than in the manner (far more than the method) of what we do. The Critical Path Method is not the crux of our project Management failures. Instead, blame must be fixed on the manner of our actions. It is my thesis that we have been employing a self-destructive Concept, an Ideology that seems rooted in aspirations of Control and Micromanagement. For those interested in what Cognitive Project Management is all about (in the alternative), there is already ample reading material available from ICS-Global.

But cutting to the chase, the Cognitive Project Management model — that was designed specifically for the Construction Industry — revolves around the Project Executor (Site Superintendent). Its policies, principles, processes, and tools all radiate outward from this essential Core. Contrast that with the Critical Path Concept, which has a different objective in mind. It is to “control,” to micromanage. It reeks of distrust and disrespect. It is confrontational and a counter-force to self-management, team empowerment, and espresso de corps. It dissipates seeks to regulate Human Will, just as it denies innovation, improvisation, and creativity.

I believe in the Critical Path Method. Sure, it has certain inherent limitations that can never be fully eliminated, and I have numerated may of them in Part 1. But I believe that its limitations can be accounted for, absorbed, and worked around … so long as we are aware of them. And that is what these blogs are intended to do. But we cannot continue with our blind embrace of, and allegiance to, an Ideology that is self-destructive. And make no mistake about it, all of the other, newer innovations waiting impatiently in the wings for their moment on stage … all of them contain inherent limitations, too (even my own brain-children). I sincerely hope that this three-part blog series on the Critical Path Myth will inspire lively discussion, debate, and passion. At all times we must remain respectful, but our signified manner will in no way weaken us in our resolve to find a better way.  Let us search together.

Thanks for reading!

Learn and Lead!


3 Comments to Critical Path Myth, Part 3: Conclusion? Delusion!

  1. Zach Reed says:

    I found the discussion of the Paper Project and Physical Project interesting. I personally have noticed a disconnect between the two and the management friction it causes (the tug-of-war). Similarly, an interesting discussion about hoping critical paths. I can certainly see how it might, in the long run, cause delays, for example, if the contractor has to mobilize/demobilize, etc.
    I think it important to work ahead of the critical path, if you will. Instead of reacting, how can we get out in front? These are very interesting and innovative approaches. Looking forward to discussing with members of my team.

  2. Murray Woolf says:

    Ivy, your advice is well-stated and should be given serious consideration by those who wish to use the Critical Path Method responsibly and effectively. Thank you for your insights.

  3. Ivy E. Mckay says:

    I suggest that critical path is not obsolete. It is not quite extinct, but certainly should be on the endangered list. The first check I perform on any schedule is to sort by total float primarily, early finish secondarily, and finally by early start. If the most critical path is not immediately and unambiguously presented, 99% of the time the schedule is broken, flawed, defective, whatever you want to call it. I never color code activities by float values to determine criticality. I simply isolate the most critical path. If it is not immediately evident, I determine why. I have filled multiple pages of legal pads recording bad practices that interfered with identifying the critical path. Most schedules I have reviewed do not come close to passing the test. Yet I have quickly and successfully elucidated the critical path using this simple sort on projects having tens of thousands of remaining activities in within hundreds of interlinked project files. This technique works with every critical path software package that I have used for the past fifteen or so years. The ultimate solution always resides in better planning.

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