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For CPM Scheduling to Succeed, Everyone Must Be a Believer!

The top reason that 50+ years after the creation of critical path method scheduling is not as successful as it should be can be said in two words, "Microsoft Project." Almost every bad scheduling practice used today can be traced back to the loose as a goose methods allowed and promoted in Microsoft Project. The CPM methodology was invented for logical workflow by logically-thinking people. Unfortunately, most construction schedules produced over the last15 or so years display unthoughful workflow logic. A reat process has been aborted. Rules of logic just do not seem to be applied these days and actual project workflow rapidly diverges form schedule "logic."

Bad schedules often lead to claims, litigation and arbitration. The problem is that the schedules are so poor and the updating process has been so badly aborted that the schedule can't directly be used. The following is a quoted section from a paper found on "Under Construction," The News letter of the ABA Forum On Construction Law:

".....Where do CPM schedules fall short when it comes time to discuss claims? In other words, as a lawyer and on a basic level, how do I attack a delay claim based on a CPM Schedule?

As with any issue in construction, the specific facts involved in the delay claim will vary. But, there are a few issues that tend to arise with some frequency. One issue that is much beyond the scope of a basics article is the debate as to the type of analysis – window analysis, as-planned versus as-built, etc. – that a scheduling expert uses to reach her conclusion. This topic has been discussed in detail in The Construction Lawyer in the past several years, and anyone seeking an understanding of those details should refer to those articles. Yet, there are several basic details about which one can inquire regarding a CPM analysis.

Generally, over the past twenty-five years, computer program management software has been used to create and generate CPM schedules. As with any computer programming, the CPM schedule generated by the software is only as good as the information being fed into the program by the project manager/project scheduler. A multitude of problems can result. For example, it matters a great deal whether the scheduled activities could be completed realistically in the time allotted on the schedule, whether the scheduler has omitted key activities, and whether the scheduler has manipulated the predecessor/successor relationships improperly.

Further, when the schedule was created and how, if at all, it was used also matters. If the schedule was the original baseline schedule showing the plan for carrying out the work, that can be a key document. Updated schedules showing partially performed work during construction can provide insight as to whether the baseline schedule was realistic for certain activities. Taking updated schedules together with daily reports can also provide similar insight. Sometimes, the schedule is never updated and is cast aside nearly immediately after construction starts.

Moreover, looking at schedules and updates will help to determine whether the delay about which the contractor or owner complains was actually on the critical path of the project during construction. That is not determinative; on occasion, a forensic schedule analysis will reveal that the parties failed to understand which activities constituted the critical path. Yet, it is strong evidence when one sees that no one identified an activity as critical until a dispute arose.

Finally, getting outside the schedules to look at contemporaneous documentation can provide extremely useful evidence in undermining a delay claim. If a contractor writes every single one of its subcontractors to blame each of the subs for delay but later chooses to sue only the best-capitalized subcontractor for all of the delay, that contractor is likely to have a problem convincing an arbitrator or jury that the “rich” sub was the sole cause of the delay.

Like many issues in construction, dealing with delay claims – especially from the contractor’s perspective – is a factually intensive investigation requiring expert assistance to establish both entitlement and quantum of damages. Undermining a delay claim without a CPM analysis can be done. I just would not recommend it."


Construction Basics: An Overview of CPM Scheduling and Delay Claims
By Anthony D. Lehman, Esq., Cohan Law Group, Atlanta, Georgia

Further Reading
7._Schedule_delay.full.pdf ANC-SAME-2010-Mod-4-Schedule-Training_TIA.pdf
From ENR Can't find good logic.pdf From ENR Poor Construction Schedules.pdf
http___www.constructionadvisoryreport.pdf Prospective-Retrospective-Time-Impact-Analysis.pdf
SHATTERING.pdf  


Logic Discussion

Good Rules To Follow

If you can say it logically you can diagram it logically. A poor logic statement leads to a poorly diagrammed workflow (schedule). An incomplete logic statement leads to an incomplete/non-continuous workflow (Schedule).

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The scope of all non-milestone activities must be included in the workflow. This means that no activity starts or finishes should dangle (be without logic). Each and every activity should have a SS or FS predecessor and a FF or FS successor.

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All hard (physical, mandatory) logic must always be included and never removed during updates. This is logic that must not be violated. Soft logic is considered preferential logic and is at the descretion of the project team and scheduler. Often soft logic is used to guide resource flow through a project, like cranage.

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Do Not Use Negative Lags! Situations .......

We will start activity B when activity A is 25% complete or when activity A has cured for 7 days. Break activity A into two parts either 25%/75% or 90%/10%. Now it can be statused properly.

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Activity Scope

Each Activity Must Have a Definitive Scope

Predecessor relationships define the conditions precedent to starting this scope of work. The successors

Activity Responsibility

Sample Content

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Milestones

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Constraints

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Construction Scheduling Attributes

These Items Are Must Haves and Do's
Believe in the methodology Buy-in To the Schedule Baseline
Keep the field involved Follow the current schedule
Provide Accurate and Timely Feedback Keep the Schedule Fully Updated
When Impacts Occur, Incorporate them Keep As-built History Accurate


How You Benefit From the Use of a Schedule
You step through the workflow mentally All project participants can input their experience
You have a guage to measure progress You can think about all the conditions precedent
You can coordinate procurement chain items You can coordinate trade activities
You can evaluate time and cost risk You can use Earned-Value


How Poor Scheduling Practice Can Spell Danger
Not following your schedule Not showing impacted logic, causing forecasting problems
Leaving out scope items creating incorrect logic Failing to include the full procurement process nor properly tieing to work activities

Process of Updating Your Schedule

DCMA 14-Point Schedule Assessment

The USA Defense Contract Management Agency (DCMA) is responsible for overseeing Federal acquisition programs. In an effort to improve the scheduling practices used, the DCMA has developed and released a 14-Point Assessment Check protocol to be used for CPM schedule reviews made by their department.


When a federal government agency creates a standard (even unintentionally), this becomes an important issue for all Project Controls specialists and even for Project Management.

 

When billion-dollar programs are being rated on a Pass/Fail system and other software makers are embedding and advertising the 14-Point Assessment Checks into their products.


The DCMA 14-Point Assessment Checks consist of the following tests,

1 Logic
2 Leads
3 Lags
4 Relationship Types
5 Hard Constraints
6 High Total Float
7 Negative Total Float
8 High (large) Durations
9 Invalid Dates
10 Resources
11 Missed Tasks (Activities)
12 Critical Path Test
13 Critical Path Length (CPL1)
14 Baseline Execution Index (BEI)


The 14-Point Checks are only interested in analyzing activities that are actual tasks (with duration) and only those that have not been completed as yet. These activities are referred to as, “Total Tasks.”


Formally, the DCMA definition of Total Tasks is any CPM activity that is not any of the following:

Summary Task or Subproject task
An Earned Value Type of Level of Effort
Zero duration tasks or Milestones
Activities that are 100% complete

 

Once the pre-check statistics are captured, one may then proceed to the 14 Checks as follows.


DCMA Check 1: Logic


The old set of checks only contained one check for this category (Missing Logic) while the second has two such checks to determine the quality of the logic used, giving us a two-part check. The first two version counted activities while the 09NOV09 version counts relationships.


1a. Missing Logic:


All incomplete Total Tasks should be linked. The original 14-Point Assessment Check instructions only identified missing predecessors. The revised rules indicate that activities missing successors should also be counted, leading to a possibility of double counting and counting the required finish activity in the schedule. The number of tasks without predecessors and/or successors should not exceed 5% of the Total Tasks or this test has is qualified as having Failed.


1b. Dangling Activities:


Added in the second revision was a guideline to identify Total Tasks that have only a start predecessor relationship or only a finish predecessor relationship and not both. Activities that do not have a logic to initiate the start or logic after completion are poor candidates for being able to display the results of unplanned delays.


The DCMA recommends that these types of activities should be investigated as either their start or finish is not constrained. There is no Pass/Fail criteria listed for this test.


This condition is more often found in MS Project schedules, as it does not allow for relationships pairs such as Start-to-start and Finish-to-finish to exist between the same two activities as P6 and Open Plan do.


DCMA Check 2: Leads


For this check, the number of Total Tasks with a ‘lead’ (negative lag) as a predecessor are totaled. The DCMA feels that leads should not be used so if any are found, then this metric is evaluated as “Failed.”


This metric defines “leads” as relationships with a negative lag value. Using the term, “lead” to mean a relationship with a negative duration is not a universal definition. Many textbooks on the subject state that the words, lead and lag mean the same thing and can refer to the duration of any relationship. Instead of the term “lead,’ most of the construction industry calls this phenomena a negative lag.


The banning of the use of negative lags is also not based upon any universal scheduling principle. To my knowledge, no major construction scheduling textbook supports this policy. Some contracts do forbid the use of negative lags but in many cases, but this can often end up as a contentions and possibly risky requirement. By denying the Contractor from communicating their intent, this reduces communication and understanding between parties, not increases it.

Unless forbidden by explicit wording in the contract or specifications, rejecting a schedule based on this criterion is a rash and risky thing to do.


The reasoning given for this metric is that the critical path and any subsequent analysis can be adversely affected by using leads. The DCMA says that the use of leads distorts the total float in the schedule and may cause resource conflicts. The DCMA supports the need for this test because, “Leads may distort the critical path.” The Integrated Master Schedule Data Item Description (IMS DID)[2] says that, “negative time is not demonstrable and should not be encouraged.”


If you are trying to evaluate this metric using a P6 or Open Plan schedule, the DCMA recommends that you “Ask the program scheduler to extract this information for you.” Obviously further definition of the metric needs to be developed.


To recap, the banning of the use of negative lags is not based upon any universal scheduling principle. No major construction scheduling textbook outright supports this ban. In many cases, rejecting the use of negative lags is

arbitrary and may open the Owner to claims of interference in the prosecution of the work.


DCMA Check 3: Lags


For this check, the number of Total Tasks with a lag (defined here as a positive lag) as a predecessor are totaled. The 14-Point Assessment Check is much more forgiving of lags than they are for ‘leads.’ There was not Pass/Fail criteria listed in the first two versions but the 09NOV09 version added a failure designation if 5% of the tasks have lags. It also added a second lag metric, that all lags should be less than 5 days but this duration requirement is only listed for MS Project and Open Plan schedules, not P6 schedules.


If you are trying to evaluate this metric using a P6 schedule, the DCMA recommends that you “Ask the program scheduler to extract this information for you.” Further definition of the metric needs to be developed.


This metric defines relationships with positive durations as ‘lags.’ The use of the term lags for the exclusive definition as a relationship with positive duration is not a universal definition.


It is ironic that leads are forbidden but that lags are only discouraged. Many professional schedulers would argue for just the opposite condition. Negative lags may just indicate the overlap of discrete work while a positive lag can be used to represent actual work, which is against CPM principals.


All actual work using resources should be accounted for as an activity. Even if a positive lag were to stand for a non-resourced condition such as “curing concrete”, this type of duration would be more accurately described using an activity with its own calendar defining the 24-hour nature of this ‘work.’


DCMA Check 4: Relationship Types


For this check, we count the number and types of predecessor relationships to Total Tasks. If at least 90% of the total predecessor relationships to Total Tasks are the Finish-to-start type, then the metric is passed, otherwise it has failed.


Of course it is unusual to see Start-to-finish relationship types and most will agree that they should only be rarely used but the claim that they are “counter- intuitive” is bizarre. This is not an industry term and even if it were well defined, arbitrarily denying counter-intuitive elements of a schedule opens up a whole new ‘can of worms.’ Using the justification something is “counter-intuitive” is a poor position to argue unless this term is specified in the contract.


The stated philosophy behind this check is that, “FS relationships provide for a logical path.” This simple statement (or more importantly, the negation of the

opposition condition that other relationships do not provide logical paths) is unsupported in current scheduling literature.


If you are trying to evaluate this metric using a P6 schedule, the DCMA recommends that you “Ask the program scheduler to extract this information for you.” Again, further definition of the metric needs to be developed.


Unless forbidden by explicit wording in the contract or specifications, rejecting a schedule based on 90% Finish-to-start relationships is not supported by current scheduling practice. “Failing” a schedule solely based upon the fact that less than 90% of the relationships were Finish-to-start would be a poor decision.


DCMA Check 1b Dangling Relationships. This check requires the scheduler to add relationships such as a Finish-to-Finish to prevent Dangling Activities when a Start-to-Start relationships is used. This is in direct opposition to this check’s requirement that we reduce the number of non-Finish-to-Start relationships.


DCMA Check 5: Hard Constraints


The rationale behind this metric correctly states that certain types of constraints prevent tasks from being logic driven. This metric extends that philosophy by defining two groups of constraints, Hard Constraints and Soft Constraints. If more than 5% of the Total Tasks have a Hard Constraint assigned, then this test is rated as Failed.


This metric is not interested in all constraints; only ones called, Hard Constraints. The term, “Hard Constraints” is not an industry term. The first two versions of the DCMA defined Hard Constraints as those activity constraints that constrain both the forward pass as well as the backward pass. This definition also includes pairs of constraints that effectively create this condition. In P6, this list would include the following constraints or combinations of constraints,

Start On or Before + Start On or After
Finish On or Before + Finish On or After
Must Start On
Must-Finish-On (MFO) Hard Constraint
Must-Start-On (MSO) Hard Constraint
Start-No-Later-Than (SNLT)
Finish-No-Later-Than (FNLT)
As-Soon-As-Possible (ASAP)
Start-No-Earlier-Than (SNET)
Finish-No-Earlier-Than (FNET)


The DCMA says that using hard constraints will prevent tasks from being moved by their dependencies and, therefore, prevent the schedule from being logic- driven. The DCMA also states that ‘soft’ constraints enable the schedule to be logic-driven.


Finally, this test does not even address the real problem of using constraints; they override calculated dates and thus interfere with the activity’s float value. CPM is best used as a tool for highlighting the critical work that must be completed in order to complete the project on time. The use of constraints directly interferes with that process.


DCMA Check 6: High Float


This metric counts the number of Total Tasks with high Total Float. The cut-off point for the definition of High Float is 44 working days. A passing grade is awarded if 5% or less of the Total Task activities have greater than 44 working days of float.

 

DCMA Check 7: Negative Float


For DCMA Check 7, if any of the Total Tasks have negative Total Float, then this metric awards the schedule a failing grade. The ‘new’ set of checks also asks the reviewer to compute a ratio of negative tasks to Total Tasks, but still requires 0% to earn a Passing grade.

 

DCMA Check 8: High Duration


This check looks for activities with too large (or ‘high’) of a duration. The definition of High Duration is any duration greater than 44 working days. We count the number of High Duration Total Tasks and divide this by the total count of Total Tasks. The 09NOV09 edition changes the count to dividing by the total number of high duration activities in the Baseline Schedule and not the current schedule. A passing grade is granted for 5% or less of the Total Task activities having less than 44 working days of duration.

 

DCMA Check 9: Invalid Dates


The DCMA 14-Point Assessment Check #9 includes two checks; one for invalid forecast dates and another for invalid actual dates.


9a. Invalid Forecast Dates: Forecast dates are the calculated early start/finish and late start/finish dates. None of these should report dates earlier than the data (or status) date. This is not a problem that we see much using P3, P6, or Open Plan as they enforce this rule automatically but this is very possible in MS Project schedules.

 

9b. Invalid Actual Dates: Invalid actual dates are statused actual start or actual finish dates that are later than the current data date.


P3, P6, and Open Plan will allow this illogical condition of actual dates in the future. This condition is clearly wrong and will result in a failure if any such dates exist.


A final point to be made here is that the DCMA dates metrics says that actual dates may ‘legally’ fall on the status date and that computed dates must fall after the data date. This is a common misconception and is erroneous. The status date (or the Data Date) is by definition the first day that uncompleted work may commence. To be completely accurate, all actual dates must be prior to the data date and all forecast dates should be on or later than this date to be valid.


DCMA Check 10: Resources


This metric requires that all tasks with durations of at least one day should have resources. On the other hand, the DCMA also recognizes that some schedules may legitimately not use resources at all. There is no Pass/Fail grade for this metric, only the ratio of non-resourced Total Tasks to Total Tasks.


The DCMA course instructions indicate that we should consider cost as a resource. It implies that when we are considering resources that we are actually tracking cost loading and not labor or equipment resource loading.


This check does not differentiate between costs, labor, or equipment.

 

DCMA Check 11: Missed Tasks


This next metric is derived by observing the changes from one schedule update to the next (in the first two versions) or to an original Baseline Schedule in the 09NOV09 version. To identify a “Missed Task”, we are supposed to count the

number of Total Tasks whose actual finish date is later than their earlier planed finish date and note the number. The original version of the 14-Point Check had no Pass/Fail measurement for this metric. The newer version changed this to a maximum of 5% missed tasks for a Pass rating.


The goal for this metric is to measure performance compared to the baseline plan. This check is only concerned with completed activities. It does not measure on-going activities that are planned to finish later than the update period. There is also no provision for evaluating delays less than a full day (i.e. in hours.)


All missed tasks are weighed the same. Issues like Total Float and longest path are not considered. You can legitimately ‘miss’ a early finish date due to using available float or due to a preceding task delaying this one but still rate a failure in this test. Short activities are more likely to increase the missed task percentage rate than long tasks would as one delay can cause a lot of short duration tasks succeeding the delay to also be delayed.

 

DCMA Check 12: Critical Path Test


This is a ‘what-if’ test performed directly on the schedule. Its intent is to identify a current critical path activity, to grossly extend its remaining duration, and note if a corresponding extension occurs to the project completion date.

 

If the project completion date (or other milestone) is not delayed in direct proportion to the amount of intentional slip, then there is broken logic somewhere in the network. Broken logic is the result of missing predecessors and/or successors on tasks where they are needed.

 

DCMA Check 13: Critical Path Length Index (CPLI)


The Critical Path Length Index (CPLI) is one of the ‘Trip Wire checks’ that is supposed to gauge the realism of completing the project on time. Most construction schedulers will find this test a little bizarre. We are to measure the ratio of the project critical path length plus the project total float to the project critical path length. The critical path length is the time in work days from the current status date to the “end of the program.” The target number is 1.0 with a value of less than 95% as a failure.

 

Modern construction projects work to a different plan. Activity durations are typically estimated with a relativity high confidence level and then the project is managed to maintain the current plan (or better it.) Planning on slipping behind just slow enough to not fall past required project completion by the end of the project is a risky business. This is perhaps why the CPLI was invented.


DCMA Check 14: Baseline Execution Index (BEI)


The Baseline Execution Index (BEI) is another ‘Trip Wire’ check that attempts to gauge the efficiency of the contractor’s performance plan. This test computes the ratio of all of the tasks that have been completed versus the tasks that ‘should have been completed’ in the period between the Baseline Schedule and the current schedule. The target ratio is 1.0 with a ratio below 95% as being considered a failure.


This test is nearly the reverse of Check #11, Missed Tasks. Instead looking for under 5% missed, we are looking for over 95% success. The 09NOV09 version

adds the distinction that we count all baseline completions plus all completions that were not in the original Baseline Schedule. This means that added work makes it harder to get a high score.


The BEI check is a rather crude analysis that considers ‘a miss as good as a mile.’ It does not consider the amount of schedule slippage and it does not consider the allowable use of available float. Added and deleted activities further skew the results. Considering all of the issues with such a test, assigning a “Failure” rating based on this ratio is rather too strident.

 

Assessment of the Assessment

By Ron Winters


The prudent scheduler will not use the results of these checks as anything other than as a very general guide to further review. In this author’s opinion, the DCMA 14-Point Assessment tests appear to be a very uneven and immature view of a much more complex system of interlinking rules than is suggested by this protocol. It was not developed nor reviewed by a practicing body of peers.


Most of the 14 tests insist upon employing metrics on issues that are not commonly agreed upon within the scheduling community. Many of the tests do not adequately gauge the issue that they are proposed to measure. Non- standard terms are used, giving rise to interpretation problems. Based upon the lack of Industry Standards, analytic rigor, or statistical studies, the use of “Pass/Fail” labels are clearly not justified and turns what is claimed to be a Guideline into a non-supported Standard.


These 14-Point Assessment Checks attempt to create good scheduling principles that are not supported in fact or in previously published research. Some of the justifications include the statement that a failure of the test “can lead to unstable networks.” The definition of an unstable network or how this feature can cause them is entirely left to the reader’s imagination.


Finally, the documentation provided by the DCMA is insufficient and incompletely defined enough so as to be ambiguous. The first two versions of the standard did not indicate the revision level or even the status date. Thankfully, the 09NOV09 revision at least has a date.


When a software company states that they have a DCMA report/check, which version are they speaking about? Is it the “current” version that also includes such things as the redefined Hard Constraint list, the one with the Dangling Activity Check, or the earlier one? Finally, who certifies that a certain company’s DCMA 14-Point Assessment Check complies with the actual protocols? On-line documentation from some of these companies indicate that the newest 09NOV09 definitions (Hard Constraints, for instance) are not being implemented as re- defined.

Conclusion


A USA government agency has created and is enforcing the DCMA 14-Point Assessment Check as a required standard of practice. With its wide government backing and industry penetration, others are beginning to use this evaluation technique when trying to confirm the quality of their schedules. The possibility exists that the reliance on some of the proscribed checks may lead the less initiated into conformation where no real problems exist while overlooking critical CPM issues.


Software


Schedule Analyzer for the Enterprise, Ron Winter Consulting LLC, http://scheduleanalyzer.com/


Schedule Detective, PM Metrics, http://www.pmmetrics.com/


Project Analyzer, Steelray Software, http://www.steelray.com/index.php [7] Acumen Fuse, Acumen, www.deltek.com/products/ppm/schedule/acumen-fuse

Schedule Cracker, Eye Tech, www.ScheduleCracker.com


Schedule Checker, Oracle/Primavera P6, Revision 8, EPPM Release 8 Release Content Document


Open Plan, Delteck, http://offers.deltek.com/forms/ImproveScheduling


2009 Stimulus and the Impact on Scheduling”, John Kunzier of Deltek,

Inc., College of Scheduling 6th Annual Conference, Boston May 17-20, 2009


Scheduling 101, The Basics of Best Practices”, Elden F Jones II,

MSPM, PMP, CMII, 2009 PMI Global Congress

 

Links:

GAO Website

GAO Cost Estimating and Assessment Guide


The US Army Corps of Engineers schedule training references the FAR Clause 52.236-15 which contains scheduling information as well as Standard Data Exchange Format (SDEF) information, required to import schedules into the USACE management system.

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