Folks, whether they are seasoned veterans or new to scheduling, often find it helpful learning from all the different scheduling guidelines that are out there. This is because there’s a lot of sound scheduling principles and wisdom that are behind the guidelines. In light of this, here we examine the Naval Facilities Engineering Command’s (NAVFAC) Initial Project Schedule (IPS) checklist.
Perusing scheduling guidelines is a good scheduler’s practice and/or habit as much thought and consensus usually forms the foundation for the guidelines. Organizations behind scheduling guidelines include: the Project Management Institute (PMI), Defense Contract Management Agency (DCMA), United States Army Corps of Engineers (USACE), NAVFAC, and Air Force Civil Engineering Center (AFCEC).
The USACE guidelines are a prominent or widely used list of requirements for the defense industry. The NAVFAC checklist is a somewhat lengthier list of defense scheduling requirements that provides instructive insight to scheduling best practices.
This article “walks” through each section of the NAVAC IPS checklist to gather and highlight good scheduling practice guidelines. The checklist (item 7) requires creation of the schedule in Primavera P6, but many items may apply to other scheduling software programs like Microsoft Project.
General Schedule Information
Item 12 – All Constraints are Contractually Defined.
The issue with constraints is twofold: 1) you lose your continuous critical path and longest path and 2) they make the schedule static. NAVFAC recognizes the setbacks inherent with the insertion of constraints, and, therefore, limits their use. The checklist does not specifically forbid the use of constraints, but says only constraints defined specifically in the contract may be included in the schedule.
A possible constraint workaround if you want an activity, such as a project kickoff meeting, to start on a particular date is to lengthen the original duration of one or more predecessor activities upstream of the meeting until the respective meeting activity start date matches your desired activity start date.
This workaround achieves both a continuous longest path and a dynamic schedule. The one negative is that the extended activity may complete before planned when updating the schedule in a narrow window of time. If this is your situation your successor (kick off meeting) activity start date will commence earlier than desired.
The benefits outweigh this setback, because usually schedules are updated on no shorter a time span than a monthly basis. Your schedule monthly update will most likely capture both the predecessor activity duration and successor (kick off meeting) duration.
It is possible to employ a lag to the fill the time gap between the predecessor’s planned finish and the kick off meeting’s planned start. But the NAVFAC checklist specifically says in Item 64 that “Finish-To-Start relationships are assigned 0 Lag”.
Lag usage is generally discouraged in scheduling guidelines because they require explanation and they make the schedule static; the lag does not automatically update to changes in predecessor activities. So the takeaway is to avoid using lag in scheduling your project, regardless of the relationship type.
Project Requirements and Settings
Item 18 – The Project Must Finish By date is set to the current CCD.
We generally recommend holding off insertion of a project must finish by date until after definition and scheduling of all activity relationships. A project must finish by date can hide your critical path, if it falls later than your network logic’s natural completion date. It will also display too many critical paths, if it occurs earlier than your network logic’s natural completion date.
The contract completion date (CCD) is the project deadline. When you enter a must finish by date to define a CCD your schedule says your project is behind when the CCD generates negative total float; positive total float says you are ahead of schedule in relation to the CCD.
Some agencies prefer to define the CCD as a finish milestone, if that is your preference you will want to read the blog Monitoring Forecasted and Contract Completion Dates in Primavera P6.
Item 20 – Duration Type is set to Fixed Duration & Units.
After budget approval your schedule becomes both time constrained and cost constrained. This makes sense because most schedules generally have fixed deadlines and budgets. Submitted IPSs should have the fixed duration & units (work) duration type where units/time (or daily effort) is the variable.
Item 21 – Percent Complete is set to Physical.
There are three percent complete types in P6: duration, physical, and units. Duration links the remaining duration computation to the activity % complete input. It also requires the least amount of input. Physical requires more input; you must manually input the remaining duration in addition to the activity % complete. Physical, however, is the most accurate percent complete type as the remaining duration is based upon the actual work physically achieved. It also accounts for learning curves where the subcontractor may perform the remaining work at a higher production rate.
Item 24 – Total Float less than or equal to 0 defines critical activity.
Here the NAVFAC checklist divergences from the USACE requirements. The USACE says to define critical activities as longest path, which ensures you have only one critical path through the network logic. Defining critical activities as “total float less than or equal to 0” highlights all activities whose delay affects either the project end date or an activity constraint date.
This may be your preference as you may want to monitor progress in relation to a contractually defined activity constraint dates, which are allowed according to the NAVFAC checklist.
Item 37 – Calendars are defined at the Project Level.
Calendars in Primavera P6 may be global, resource, and project levels. Global calendars are preferred in many situations because they are available to all users in the database.
But global calendars are a double-edged sword. It’s great that all users can access your global calendar. The problem is that they can also change your global calendar, and, subsequently, your associated schedule, which is not good. You do not want other users making unintentional collateral changes to your schedule. Therefore, define your calendar at the project level, where any schedule changes require one to access the specific schedule project data file.
Item 50 – Activity Codes are established at the Project Level.
Activity codes may be set to global, Enterprise Project Structure (EPS), or project. Similar to global calendars global activity codes pose the threat of other users unilaterally changing the code, and, also your schedule. Another issue with global activity codes is that your system quickly becomes cluttered with many global activity codes that have limited usage. Thus, define activity codes at the project level.
Item 53 – Activity Type set to Task Dependent.
Task dependent activities schedule or calculate task start/finish dates based upon the calendar assigned to the task. Resource dependent activities level activities or adjust their start/finish dates in accordance with the assigned resource calendars. As resource leveling is a complex procedure task dependent activities are preferred for simplicity; you do not want your schedule automatically leveling resources, which it will for resource dependent type activities. So all activities, except milestones, should be task dependent.
Item 63 – No Negative Lags.
Negative lags or leads are confusing and difficult to understand. Another problem leads have is their predictive nature. You are commencing a successor activity based upon the future completion of a predecessor activity. The problem is that in reality it is very difficult to be able to predict the end of an activity or scope of work. And to link (or leverage) the start of another activity based on this end prediction is not good scheduling practice. A more in-depth discussion on negative lags can be found in this article The Negatives of Negative Lag.
Item 75 – There are no time gaps between activities on the longest path.
You want one continuous critical path or longest path through the network. Gaps in the critical path may be due to insertion of activity constraints. This is one reason why insertion of activity constraints is discouraged.
Sound scheduling principles forged in the crucible of much thought and consensus form the basis of the NAVFAC checklist. Schedulers preparing schedules for NAVFAC or other government agencies would benefit from studying this checklist.
The NAVFAC checklist requires the use of Primavera P6, but some of the checklist items are relevant to any standard scheduling software program.
Takeaways include defining calendars and activity codes at the project level. And do not use negative lags (leads). Also, schedules beyond the planning stage should have the fixed duration and units duration type. The fixed duration and units duration type is preferred for progressing the time and budget constrained project schedule. Further, the physical percent complete type more accurately describes schedule progress, and is required by the NAVFAC checklist.
Yes, while the NAVFAC checklist is specific to Primavera P6, much of its guidance forms the foundation of sound standard scheduling principles, and is worth studying regardless of the tool you use.
You can download the NAVFAC Baseline Checklist here.