The Naval Facilities Engineering Command’s (NAVFAC) Initial Project Schedule (IPS) checklist has a number of items to consider in relation to the NAVFAC IPS longest path.
Scheduling guidelines are worth studying to increase ones knowledge of scheduling principles, which results in higher quality project schedules. Several notable rules in the NAVFAC IPS checklist were explained in detail in the our blog “A Short Walk through the NAVFAC IPS Checklist“.
Now we want to take a closer look at guidelines related to the NAVFAC IPS longest path. The guidelines have several rules specific to the longest path that are worth discussing.
This article discusses the reason behind several NAVFAC IPS checklist item stipulations for the longest path.
NAVFAC IPS Checklist Longest Path
The NAVFAC checklist is outlined in numerous categories. One of these categories is for the longest path. But a rule having significant impact on the longest path is in the general schedule information category. Specifically, this is item 10 which states “critical activities defined as Total Float less than or equal to 0”. This is significant because defining a critical activity as Total Float less than or equal to 0 will capture both longest path activities and activities driving an activity constraint.
This stipulation means the schedule, depending on activity constraints, may have more than one critical path. Multiple critical paths adds confusion to schedule optimization efforts. It is worthy to note that this specification differs from the US Army Corps of Engineers (USACE) requirement that critical activities be defined as longest path.
The NAVFAC IPS checklist provides additional longest path guidance. Longest path review should include the following item considerations:
Item 72 – Government activities are not arbitrarily placed on the Longest Path.
This addresses the “hot potato” blame game deciding who is at fault for schedule delays. The more Government activities on the longest path the more the subcontractor can point to the government for schedule delays. The government is not trying to obfuscate responsibility; the government simply asks for a logical reason their tasks are along the longest path through the network.
Item 73 – The longest path is made up of activities that you expect to drive project completion.
The scheduler should review the longest path to confirm that tasks along the longest path are in fact major driving efforts on the project schedule. If not, the scheduler may need to revisit duration estimates.
Item 74 – The longest path shows reasonable work flow and sequencing.
Tasks should indicate a reasonable and thought out order of project efforts.
Item 75 – There are no time gaps between activities on the longest path.
The schedule should have one continuous longest path from start to finish.
The longest path should flow from one activity to the next according to network logic. Time gaps may indicate the presence of an activity constraint. Item 12 states that “all constraints are contractually defined”. So constraints come with restrictions to limit their usage in the schedule. One way to maintain a longest path when there is the presence of constraints is to define positive lag on the constraint’s successor activity. However, item 64 specifies that “Finish-To-Start (FS) relationships are all assigned 0 Lag”.
Summary
The NAVFAC guidelines provide the student of project scheduling numerous items to consider and understand the principles behind the stipulations. These principles are relevant to any scheduling effort, and are worth contemplation. In particular, are items that relate specifically to the longest path?
Honest schedulers will consider carefully before assigning the government activities on the longest path. It’s acceptable, but should not be done in a scheme to shift and/or avoid responsibility. Activities along the longest path should also be major schedule drivers. And should be a well-thought logical sequencing of project efforts.
An important takeaway is to limit insertion of activity constraints to support one continuous longest path from project start to finish. An intermittent longest path or a longest path with discontinuities is a project show stopper, and must be addressed before receiving final approval of the project schedule.
Multi-hundred million dollar projects have been suspended until resolution of longest path discontinuities. Yes, you read that correctly: government bodies such as the DoE, DoTs, DoE, can and will put multi-hundred million dollar projects on hold because of problems with the longest path in a schedule. A student of scheduling would therefore do well to think through these longest path guidelines.