Author: P. Epperson

Construction Scheduling. Too much Detail.

When we develop the Baseline CPM Schedule for a construction project, we need to develop the WBS to establish the project deliverables.

To what level of detail is this required?

The general idea is to decompose the project deliverable down to the Work Package level. For construction, this could be taking the WBS down to an area of structural foundation for a large project. It is really taking the deliverable down to the point that it can be easily identified and measured.

We then develop the “work” activities that need to happen to produce this deliverable.

Basically, we develop the list of activities, sequence them, assign the resource(s) and determine the Activity Duration, and assign the activity’s Budgeted Cost. There are also the Activity Code, Calendar, and Role assignments…

Many specifications have limits on the number of Work or Calendar Day duration a “work” activity may be assigned. A good rule of thumb is “not to exceed the reporting period”. I like to cap my “work” activities at 20 Work Days or less. An activity should only have one responsible party performing the work. If an activity only has one party performing the work and the duration of the work is going to exceed 20 Work Days, perhaps it is best to break the work area down to allow smaller durations. It is difficult to accurately measure the performance of activities with large areas or durations.

The use of activities with large Activity Durations also leads to the use of Start-to-Start and/or Finish-to-Finish relationships to model the work which is now running concurrently with other large duration activities. This should be limited. The overuse of Start-to-Start and/or Finish-to Finish relationships is a basic problem for many detailed project schedules. Makes a pretty Gantt Chart, but does not allow adequate control and measurement of scheduled work.

Most deliverables should have activities with durations much less than 20 Work Days. They should not all be 1 Work Day unless that is actually what it takes to model the work of several parties. Usually, the “work” could be broken down to 5 days to excavate the foundation, 2 days to install reinforcing steel and any vapor barrier or blockouts, and 1 day to place concrete and an activity with a period of time for concrete curing. Breaking the work down to this level allows the work to be easily measured and managed. Too often I see a “Place Foundation Concrete” activity with a duration of 10 Work Days. No cure activity. No idea if cure time is included or not…. No idea when the excavation should complete or when the reinforcement placement starts…. Most likely, the formwork and reinforcement work will run concurrently at some point and the concrete placement will be driven by the finish of the reinforcement work and inspection. If there is a delay in delivery of reinforcement steel, we should be able to accurately model that…..

The idea is to develop a schedule which is manageable and has enough detail to control the work. Pretty simple.

If there is more than one contractor performing the work, you probably need to break down the work further. If a series of activities are all running concurrently, perhaps it would be best to break the work down into smaller areas. The goal is to use Start-to-Start and/or Finish-to-Finish relationships as little as possible. Using Finish-to-Start relationships is almost always the best way to model the work. This usually requires breaking the work down into smaller pieces…

I’m sure many of you have comments or additional insight into this subject. Please share!

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. General Progress Update Information for Owners.

When we develop the Baseline CPM Schedule for a construction project, we know we will need to use the Baseline CPM Schedule to measure performance during project execution. With this in mind, we work with the contractor to help get an acceptable Baseline CPM Schedule for the project. That’s usually a tough task, many contractors don’t believe it necessary or simply do not want to follow parts of the schedule specifications or best practice for schedule development. But, we usually end up with a schedule we can use to track progress and manage the work and changes.

I often see problems on projects once we start getting schedule updates from the contractor. Some owners believe the Original Baseline CPM Schedule is the most important schedule we measure against. This is partly true, we do need to reference the original plan as we go. But, after the first couple of progress updates, the remaining plan to execute the project has changed. Sometimes there have been major change orders, delays or resequencing of work. When this happens, we need to revise the Baseline CPM Schedule. Most of us understand the need to re-Baseline.

What I find many do not understand is how important it is to keep the progress updates valid. The owner really needs to be able to validate Actual Start and Finish dates in addition to agreeing with the partial progress reported for work in progress. These three items determine the as-built schedule condition and establish the plan to continue with project execution.

That is what the owner can see in the Gantt Chart pdf.

What about what goes on behind the scenes when the contractor is applying the update data? Who is watching to see if logic is changed? If calendars are adjusted? If resources are revised?

There are many things the owner cannot verify or validate that absolutely need to be confirmed. This is where the Owner’s review and oversight of the scheduling process come in to play.

With each progress update submitted by the contractor, we look at several areas to ensure the schedule integrity is maintained.

First, we simply make sure the network logic is still complete. This also includes verifying there are not any open ends such as a Start-to-Start, SS successor relationship which leaves the finish of an activity open. We run diagnostics to uncover what logic, durations, calendars, and activity additions/deletions have been revised and analyze this data to understand what the changes actually do to the schedule. We need to determine if the contractor’s revisions of a few relationships from Finish-to-Start, FS to SS shortens a network path enough to shift the Critical Path. It may be unintentional, but we must still review and validate. Sometimes these relationship revisions are done to correct Out-of-Sequence, OOS logic, sometimes it is done to recover lost time and bring the schedule completion back.

We look for calendar changes which often affect Total Float and the Network Path. We look at changes to durations and flag lack of progress for activities not projecting to complete as planned. This needs to be investigated to determine the causation. We verify Out-of-Sequence Logic has been corrected to keep invalid relationships from driving remaining logic and dates.

We analyze the actual progress of the project as a whole and also look at the Critical Path work performance as well as Near Critical Path(s) work performance. Doing work on the Critical Path is important. Doing work on the Near Critical Path(s) is also important. However, if work not yet Near Critical is not executed aggressively, the result in the stacking of work adds unachievable resource demand to the remaining scheduled work. This often drives the search for the “miracle” towards the end of the project….

We have to monitor all this, and you really can’t get that kind of insight from the Gantt Chart pdf.

We have to validate the progress update schedule. After all, the revisions to pull back the schedule and make minor sequencing changes have obviously resulted in logic or other changes. We need to verify that the schedule still meets the schedule specifications and best practices. Each progress update becomes the basis for any time impacts for the next performance period. The schedule update has to be valid.

I will elaborate more on how we accomplish many of these tasks in future posts.

I’m sure many of you have comments or additional insight into this subject. Please share!

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. Contract Duration and the Finish Date.

When we develop the Baseline CPM Schedule for a construction project, we need to know the contractual dates for Beneficial Occupancy, Final Contract Completion, and any other contractually required dates for deliverables.

The calendar day difference between NTP and the Required Contract Completion Date determines the project duration in Calendar Days.

Various organizations use various names for these required dates. There is NTP for Notice to Proceed. This can be for design, construction of any segment of the project. In construction, it is usually for the start of construction, but Design-Build projects typically have NTP for Design and even interim NTP dates. The names for Contract Completion vary greatly. Beneficial Occupancy; Start Operations; Contract Completion Date; BCOM…. The list is long.

Whatever the terminology, we have to end up with a project schedule that fits into this period of performance.

We develop the schedule based on input from all stakeholders. We verify we have included the entire scope of the project. We make sure we sequence the work in a constructible manner. We use accurate durations for work activities.

Does the Project Schedule then report a finish date which meets the contractual requirement?

More often than not, it does not. Correcting this is another issue.

So, what drives the contractual finish date? Is it a business decision based on a valid business need? Is it an organizational need for a change in operations? Is a specific date to meet some public good?

Many times, the contract completion date has been established based on someone’s best guess to create the period of performance. Sometimes, the Capital Projects Team decided on the period of performance based on another similar project. Sometimes funding issues drive the period of performance.

Whatever the reason, the project must be completed within the period of performance or some type of punitive action will result. This is just one more reason to develop a robust and dynamic CPM schedule with which the Project Team can manage work proactively. The effort expended to create and manage a quality CPM schedule is easily recovered with the savings gained through improved management of work and adherence to the required finish date. Whatever it is called…..

I’m sure many of you have comments or additional insight into this subject. Please share!

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. Schedule Revisions and the Reality Check.

When we finish updating Actual Progress for the Schedule Update, (See previous post), how do we revise the schedule to maintain the contract completion date or whatever period of performance is required?

How do we get the Project Schedule back on-track?

More often than not, the Schedule Update models actual performance which does not support an on-time project completion. Work slips, production isn’t what was planned, deliveries are late…..

The Project Team usually has to make Schedule Revisions to “recover” the lost time. This is sometimes called “crashing” the schedule.

This is an exercise based in future failure.

When most schedules are developed, they are already overly optimistic because the Project Team had to “crash” the schedule to even create the Project Baseline Schedule. Once the work starts and progress slips, the work starts to stack. Even if the Critical path work is completed sufficiently to maintain the Critical Path, all the other work activities have to maintain or beat their dates. If not, that work pushes out and soon stacks up to double the resources necessary to complete the work later. If we couldn’t complete the work as-planned, why will we be able to complete it later, when we have fewer resources to work with? What is going to change?

Back to the Schedule Revision process. The process is basically looking at the current Critical Path and deciding which activity duration can be shortened cost-effectively or which logic for sequential activities can be changed to have them run concurrently, with a slight bit of lag time. Then the schedule is calculated again and this process is repeated until the schedule is “on-track”.

Unfortunately, this is also when contractors are pressured into completing work in less time than they may have budgeted or have the resources to support. But, this is often exactly what happens.

Now we have a schedule for the remaining project work which is most certainly impossible to execute. Sure, the owner will issue change orders which may provide some concurrent delay the contractor can attach their lack of progress to. But most likely, there will not be enough changes to cover all the time lost.

It is my opinion that the best thing the Project Team can do, is establish the most realistic expected Finish Date for incomplete work. This also applies to establishing the most realistic delay (lag) in concurrent work planned to recover time. If these revisions are not realistic, the contractor can’t support the shortened duration or additional resources necessary, then we are just kicking the proverbial can down the road.

We should, as Schedule Professionals, provide the “reality” of the project performance and the realistic plan to execute the remaining project work and let the Project Stakeholders know sooner than later that the project cannot, under the current cost or resource constraints maintain the contract completion date or period of performance.

I’m sure many of you have comments or additional insight into this subject. Please share!

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. Progress Updates and Incomplete Work.

When we update Actual Progress for the Schedule update, how do we report the incomplete activities? How do we report the progress for the work, (activities) currently in progress?

We know how to report the completed work.

More often than not, there are many activities which may have Actual Start Dates in the previous Update Period. There are also activities which will have Actual Start Dates and Finish Dates in this Progress Update. There will also be activities which will not have Actual Finish Dates. The way we report the Actual Progress for these activities is crucial to maintaining the schedule validity.

The Project Team has to decide just how much of the “work” represented by the activity is complete. What percentage of the work is complete…. This should be a measure of quantity completed.

Too often, we see the Duration Percent Complete set as the Progress Percent Complete. This is not the best method of reporting the Actual Progress.

If the Duration Percent Complete is used to report the Actual Progress, the schedule is not going to be valid. Setting the Duration Percent Complete to a specific value results in the program calculating the Remaining Duration. This, in turn, establishes the scheduled Finish Date for that activity. This is the problem. The scheduled Finish Date for an incomplete activity should be set by the Project Team as the date they expect the work for that activity to actually finish. Unless this scheduled Finish Date is used, and the successor activities driven by the remaining duration and logic for the network string are allowed to calculate the new scheduled dates, the schedule is not valid.

Using Duration Percent Complete does not, in most cases, represent the actual schedule progress and accurately model the remaining plan to execute the project.

A better method to report Actual Progress is the use of Physical Percent Complete. This value is based on the actual work in place. The Duration Percent Complete should be the result of setting the scheduled Finish Date or Remaining Duration based on Project Team input. This allows us to have the value of work in place and the value of the time used to complete this work in place. We can then easily see if we are meeting the required productivity rate for this work activity.

The next step, after entering all the Actual Dates and Scheduled Finish Dates, (or adjusting Remaining Durations for in-progress work), is to “schedule” or calculate the project schedule. We should then look at the Out-of-Sequence, OOS logic and make corrections.

I believe in correcting all the OOS logic each update. Many do not consider this necessary and others consider it only necessary for activities on the Critical or Near Critical Paths. Some Schedule Specifications or Requirements address this issue, but most do not. I consider it a best practice for keeping the schedule valid for the as-built progress and do not like the idea of the OOS logic driving future dates and logic, which can happen.

Using the Physical Percent Complete for reporting Actual Work in Place, letting the Duration Percent Compete report the actual Activity Duration consumed, and correcting the OOS logic is the first part of the Progress Update process.

This allows us to maintain the schedule as a valid tool for planning the remaining work from the Data Date forward. If the Progress Update results in a late Finish Date for the project, then we have some work to do. This is, more often than not, the case. We can make adjustments to the plan to complete the remaining work through Schedule Revisions. This issue is a subject for another post.

It is my opinion that the best thing the Project Team can do is establish the most realistic Progress Update possible, each Update Period. If we don’t know where the project actually is, how can we drive the project to a successful completion? If the Progress Update is not valid, the Critical Path and Near Critical Path(s) are most likely not valid. How then, can a Project Team manage the Critical work? How can the Project Team identify and address work which is actually lagging?

We should, as Schedule Professionals, provide the “reality” of the project performance.

I’m sure many of you have comments or additional insight into this subject. Please share!

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. Activity Codes and Organization.

When the schedule is developed, how do we determine the Activity Coding for each activity?

What is an Activity Coding Structure?

Many PM’s don’t know or care about the Activity Coding. Unfortunately, they are missing out on the use of a great tool.

I’d like to offer several reasons for spending the time and energy to develop and use Activity Coding.

Activity Codes are developed for the schedule based on specification requirements and a Schedule Management Plan. It can be as simple as a specific assignment for phasing. More often an Activity Code Structure is developed to include specific phasing of the project, responsibility for work, areas of work, CSI assignment, weather sensitive or not, and type of work.

I like to develop the schedule Activity Code Structure prior to building the activities out. I usually do it when I set up the calendars, resources, and WBS. After all, it is based on the plan for organizing the schedule and reporting for the various stakeholders. It is also used for schedule analysis.

Once the Activity Code Structure is set up, (Along with the calendars and calendars, resources, and WBS) we can start building out the activities for the project schedule.

If you develop the string of activities for a specific trade, which is how I usually start out the development of each trades’ work, it is easy to assign the resource and activity coding as you assign the activity calendar and resource. By having already established the Activity Code Structure, there is already a ready list of choices. This prevents inadvertently assigning similar coding for the same item.

So, we develop all the activities by WBS with the appropriate activity calendar, resource and Activity Coding.

Now we can sort and group in a multitude of ways based on the Activity Coding Structure we planned and executed.

We can group by responsibility and sort by Start Date if we have already assigned the logic. Or we can sort by Activity ID if we added the activities sequentially in the order of execution. This makes it easier to manage adding the logic. We can then group by area to see how we need to coordinate the work between trades. This is very handy for establishing preferential logic.

We most often use the Activity Coding for Layouts and presentations.

Grouping the schedule by phase and then area is a popular layout.

We can also filter by responsibility which allows us to analyze the planned sequence for each trade and verify scope. If the logic is complete and there are many activities planned for the same work period, resource allocation may be an issue. This layout allows us to assign preferential logic to assign resource flow.

There are many reasons for developing a robust Activity Coding Structure. We use them often and they offer a great method of organizing the activities for analysis.

I’m sure many of you have comments or additional insight into this subject. Please share!

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. Activity Durations and Unicorns.

When the schedule is developed, (after the project has been broken down and organized into the WBS and the activities have been developed to support the deliverables), how do we determine the duration for each activity?

How do we accurately determine the work period for each activity?

There are several ways this task is approached. Some are better than others….

I believe we can all agree that knowing the required work quantity and production rate per day is the best input we can have to accurately calculate the duration. How often do we actually have that much detail?

More often, the project team determines the durations based on their “feel” for how long the work will take based on similar work from the last few projects. This is not necessarily a bad thing. This is historical data and is very useful.

The problem is that we tend to be optimistic. The larger the piece of work is, the more difficult it is to accurately determine the duration, by “feel”.

Typically, the activities are all developed based on input from the project team, the constrained finish date is applied and then the schedule is “calculated”. Usually, we do not make the required finish date.

Now we start crashing the schedule to pull the finish date back.

We’ve all seen videos of buildings constructed in a week and other supernatural feats. So, it stands to reason that we can build anything within any timeframe, right? If the owner wants the project by the date in the contract, we have to crunch the schedule until it shows we can deliver on time.

As we know, a very high percentage of projects do not finish on time. This often leads to claims and poor performance reviews.

Is it possible that we set our projects up for failure at the very beginning? Do we assume we can provide a finished project within the contract duration just because the owner has specified the period of performance?

If the schedule is constructed using “most likely” durations for all activities with reasonable logic and the project is then constrained to finish on whatever date that produces, there is still a good chance the project will finish late. It could finish early, but that seldom seems to happen.

If the durations are based on pessimistic durations, the project will still tend to use the time allowed leaving little room for problems towards the end of the project.

If we place a contingency activity at the end of the project, we can work towards an early completion hoping we magically finish on or ahead of time.

Or, we can put the effort into building very detailed schedules with solid logic and durations and then execute the projects per the schedules, as well as possible.

Any way you slice it, a poor schedule does not work. An aggressive schedule is not realistic and will soon fall apart, a pessimistic schedule will also fail due to a lack of aggression to complete work.

A detailed schedule, with input from all team members, does not guarantee success, but it does provide a realistic path to get there. It is up to the project team to execute based on the plan. But they can’t do that without a solid schedule.

I’m sure many of you have comments or additional insight into this subject. Please share!

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. Critical Path and Total Float.

Can the Critical Path for a project have different Total Float values?

Does the Total Float value determine the Critical Path?

When the Baseline Schedule is developed, all the activities should have the appropriate calendars, durations and logic applied. This creates the schedule network of activities.

Within this network of activities, there are many paths which run through activities linked by mandatory or “hard” relationships. For example, the structural steel shop drawing development and submission should drive the review of this submittal which will then drive the procurement with lead time to drive the delivery and then the erection. Almost all the trades and materials have these “hard” relationships which form the work sequence for that network path.

There are also discretionary or “soft” relationships. For example, the ACT grid could be installed prior to the wall painting. I prefer to run the grid after the walls are painted, but it may be necessary to install the grid first to allow light fixture and register installation to start earlier. This may be sequenced at the discretion of the Project Manager or Superintendent.

There are external relationships, but these are usually handled within the schedule itself. But it is possible to link activities in one schedule to work in another schedule….

Once all the mandatory and discretionary relationships are assigned, and the calendars and durations are assigned we can “schedule” the project. This is what sets the schedule network up.

This is what also determines the Longest Path and Total Float values.

If there is not a finish constraint applied to the project, the end date will float dependent on the network. The Total Float value will be 0. If you sort the activities by Total Float value and look for the next continual sequence of work activities with a Total Float value close to 0, you will most likely find the Near Critical Path. Just be aware that this Near Critical Path is based on the Total Float values only and will not necessarily be the logical Near Critical Path.

If you have a constrained finish date for the project, the Baseline Schedule should have a Total Float value of 0. But as soon as you start updating actual progress, the work will force the various network paths to push or pull and this will change the Total Float values. The Longest Path will still be the Critical Path, but the Total Float values may be positive or negative values. Again, the next continual sequence of work activities with a Total Float value close to that of the activities on the Critical Path should be the Near Critical Path, based on Total Float values only.

Recognizing the Critical path is the Longest Path is the basis for properly managing the work. Recognizing the usefulness of the Total Float values for identifying Near Critical Path work is also valuable.

This is a fairly simple concept. But, there are many discussions about what determines the Critical Path.

Not using Longest Path as the definition to use Total Float values is a tool we use for analysis. Much as we use Progress Override instead of Retained Logic for analysis.

Interim Constraints play into the schedule network and affect the Longest Path and Total Float values. But this is another subject for the future….

I’m sure many of you have additional insight into this subject and can help explain the concept. Please share!

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. Schedule Progress Updates and the PM.

The Project Manager is responsible for many deliverables and processes for the project.

Scope, cost, communication, time, and quality.

Part of managing the cost and time is the coordination of work and subsequent reporting of work completed.

Many projects base the periodic invoicing on the percentage of work completed for that period. Others use Milestones for payments. There are other methods as well. For this post, we will work with the percentage of work based on the progress completed for each activity.

Correct updating and reporting of the schedule progress is a large part of the process. And invoicing is a big deal!

How does the PM report on the work completed? Should they use the percentage of time used for the activity? Should they use the percentage of actual cost expended? Should they use the percentage of work in place?

Depending on the contract type, there are options. Personally, I prefer to base the invoicing on the percentage of physical work in place. After all, why would an owner pay for your time or actual expenses, unless the work is T&M?

To update the progress based on physical work in place, you simply manually assign the physical percent complete for work in progress and set the scheduled finish date based on the planned remaining duration or finish date. It is that simple. The cost can be calculated in the software program or in a spreadsheet.

One of the useful things about using physical percent complete and letting the remaining duration or scheduled finish determine the duration percent complete is the variance between percent complete this creates.

If you have completed 50% of the work and the remaining duration or scheduled finish date results in a duration percent complete of 70%, it is obviously taking longer to complete this work than planned.

Perhaps this indicates a learning curve for this work. Perhaps there was a delay in material delivery once the activity started. There could be many reasons. But, the PM should know the reason and they cannot know to find out if they do not have an indicator that there is a problem.

Many people just assign the percent complete as duration percent complete and let the program assign the scheduled finish date based on the original duration and remaining duration values. This is a problem for several reasons. First, this method models the time used and remaining, not the work in place. Second, the scheduled finish date is based on the assumption that the productivity rate is as planned. Seldom is this correct. Finally, letting the duration percent complete value calculate the scheduled finish date does not model the remaining work for the project accurately. Basing an invoice on this method will result in inaccurate invoices for work in place and a schedule that is not valid for the remaining work. It’s a good practice to be accurate in these areas.

Although it is not often used in the typical layouts I see, displaying the “At Completion Duration” column in the layout also provides a quick flag for activities that are exceeding the original duration. Most layouts display the “Original Duration” and the “Remaining Duration” columns. But this doesn’t really alert the PM to a potential problem with activity progress and productivity.

I’m a big supporter of using physical percent complete for work in place and setting the scheduled finish date for work in progress by revising the remaining duration value or setting the date based on field input. I also like to display the “At Completion Duration” column in my layouts. I think providing the Project Manager with as many tools as we can to help them make intelligent decisions for managing the work is our primary function.

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. Why Work When We Can Wait?

When the baseline schedule is developed correctly, the schedule logic is complete, activity durations and activity calendars are assigned, resources with cost may have been assigned, and activity coding is developed and assigned.

All of this creates the schedule network. This schedule network is made up of many sequences (logic paths) of activities.

Once the schedule is calculated (forward and backward pass), the schedule network will provide scheduled dates for activities not yet complete. At any given time, a small percentage of activities will have scheduled dates which show they should be starting and completing within a defined period of time, (say this week or this month…).

Some of these activities will be on the Critical Path. Some will be on the Near Critical Path(s). Some will have Total Float values which allow them to remain unstarted or incomplete for a period of time dependent on the Total Float value.

We all understand that the work on the Critical Path needs to be driven at all times. We understand that work on the Near Critical Path(s) also needs to be driven so it does not lag and shift to the Critical Path.

What about the activities with Total Float values which allow the work for these activities to lag without affecting the Project Completion Date?

Should this work be executed when it is convenient? Should this work be pushed out until it is on the Near Critical path(s)?

Part of the CPM Schedule development process was the analysis of the resources for activities to verify a specific resource did not have more activities scheduled to be underway than the resource could support. This can be done manually or using software programs that run Monte Carlo analysis for resource leveling.

That said, why would we want to allow work to slip? It is my opinion that any work which can logically be executed should be executed as long as the resources required do not exceed the planned resources for that time period. But, sometimes it is better to add resources to execute the work for a variety of reasons.

By allowing work to slip, only because there is no schedule driven reason to execute the work at that time, the work will eventually push out until the activities with a specific resource assignment are stacked resulting in an overallocation condition which forces some of this work to push out due to lack of resources. Whether the schedule is resource loaded or not, we all know that a subcontractor can only do so much with the forces they have on the project at any given time.

Allowing the work to slip also increases the risk of a late completion due to the potential of shifting of the Critical and Near Critical Path(s).

Finally, allowing work to slip has a negative impact on the schedule cost curve and distribution plan. The project may be reporting an on-time completion and the Critical Path may have an acceptable Total Float value, but if work is pushing out, the completed values will produce an unacceptable Cost Variance (CV), Cost Performance Index (CPI), Schedule Variance (SV), and Schedule Performance Index (SPI).

Projects with poor Earned Value metrics seldom recover.

I say, if the work is available to be executed, the resources are available, and executing the work will not lessen the focus on the Critical and Near Critical Path(s), it is wise to work in where you can, when you can.

I’d love to hear what you think!

Please visit https://conschmanservices.com to learn more about Construction and Schedule Management Services, LLC

Please visit my LinkedIn account to learn more about me.

Please visit my “The Blue Book” ProView.

Paul Epperson CCM, PMP, PSP, PMI-SP