Construction Scheduling – Construction and Schedule Management Services

Construction Scheduling. Milestones and Constraints.

From time to time, I hear a project team member refer to a constraint when what they are actually referring to is a milestone.

This is really a “jargon” issue. I’ve heard people refer to a milestone with the intention of the milestone being a constraint on the project. I’ve heard people describe a project constraint as a schedule constraint.

It gets a bit confusing.

A PM may consider a required completion date of a phase of the project as a milestone. To a scheduler, this is an interim milestone and may or may not be date constrained, (Constrained with a schedule constraint assigned in the CPM schedule software program). If this milestone has a contractually required date, a scheduler may assign the appropriate date constraint. If the milestone is just for reporting purposes, the scheduler need only make sure the appropriate activities drive and are driven by the milestone activity.

A PM may refer to a project constraint, like the coordination with an owner delivery or requirement from outside of the project scope and control of the contractor. A scheduler will consider this an external constraint and may assign an appropriate date constraint. (If the date constraint would be a “start no earlier than”, I sometimes prefer to use a lag to NTP… I like to avoid the use of date constraints….).

A scheduler shouldn’t assign date constraints to every “milestone” or “constraint” referenced by the project team. The use of date constraints should be minimized and only applied when necessary.

The PM should understand that they may need to clarify when they really need a date constraint applied. The scheduler may not pick up on the requirement based on discussions among the project team.

The communication between the project team and the planner / scheduler is critical to the successful development and management of the project schedule. The different “jargon” we use can make this more difficult. We need to be aware of this and be sure to clarify when we’re unsure.

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 Performance Measurement, Part 5. (For Owners).

When monitoring and responding to the Contractor’s schedule performance on the project, how do you know if the schedule update is even valid for use?

When we review a schedule progress update, we need to first determine if the schedule update is a valid update. By that, I mean is the logic still complete? Have there been any revisions with this update that result in the schedule not meeting the contract requirements or best practices? It doesn’t take much to render a schedule useless….

There are most likely logic revisions, changes to lag values, or possible changes to calendars or assignments. There are also deletions and additions of activities and/or Activity Relationships. Then there are changes to quantities or Resources which may impact Activity Durations or Resource Calendars.

For this post, we will address the lack of correcting Out-of-Sequence, OOS Logic.

Personally, the first schedule “quality check” I make is for complete logic. Please see the previous post, Schedule Performance Measurement, Part 2. (For Owners).

Next, I check for changes to Relationships and Relationship Lags. Please see the previous post, Schedule Performance Measurement, Part 3. (For Owners).

I then check for changes to Activity and Relationship Calendars and Calendar assignments.

But, my personal pet peeve is OOS Logic which has not been addressed.

When the Contractor is assigning actual and expected dates to the schedule update, while assigning the current progress for work in progress, it is common and acceptable for actual work in the field to have been executed differently than planned. This results in Out-of-Sequence, OOS Logic.

Primavera P6 provides a Schedule Log with lots of information. One of the things this log provides is a list of activities with OOS Logic. This is simply a list of activities with assigned Actual Dates which are not progressed the same as the Schedule Network Logic.

For example, if activity A drives activity B with an FS Relationship and Activity A is assigned an Actual Start Date with a projected scheduled Finish Date and activity B is assigned an Actual Start Date, activity A will show up on the Schedule Log as having OOS Logic because activity A does not have an Actual Finish Date prior to activity B actually starting. This condition is simple to correct. We simply change the logic to an SS relationship. This allows the as-built relationship to match the revised logic. If activity A has not actually started and activity B is assigned an Actual Start Date, then more work must be done to correct the OOS logic. Activity A is obviously either not progressed and missing the Actual Start and Finish dates or the actual sequencing of the work is being executed differently than planned and activity A should no longer be the predecessor to activity B.

If the issue is OOS logic, it should be addressed. Leaving OOS logic in the schedule allows the now incorrect logic to drive the successor activity dates, which is incorrect. This happens when we use Retained Logic, which most schedule specifications require. It is also best to use Retained Logic to allow the planned logic to drive the schedule. We just have to correct the OOS logic with each update.

Not correcting OOS logic with each update can produce erroneous specific Network Path scheduled activity dates. This can create a Critical Path based on the original logic which is no longer valid due to the actual OOS work in the field. We want the Critical Path, and Near Critical Path(s) to be based on the most accurate progress input and plan to execute the remaining work.

Typically, correcting OOS logic for driving activities on the Critical Path will shorten the Remaining Duration of the Project Schedule. I prefer to correct the OOS Logic immediately after I assign the actual dates, expected dates, and actual progress. This way, when we need to determine the best method of recovering any lost time, we are working with a valid Schedule Network.

The same applies to Near Critical Path(s).

That said, understanding the impact of the uncorrected OOS Logic, and reporting those findings is important to the Owner. Personally, I do not consider the Schedule Update valid if the OOS Logic is not corrected. But many schedule specifications do not address this issue.

As Planning and Schedule Professionals, we need to provide the Project Team with the “tools” they need to manage the project. The owner needs to know what the performance of the actual work in the field is, compared to the planned performance. Unless we have a valid schedule update to measure with, and against, and understand the impact of acceptable schedule revisions, we cannot provide an accurate measurement.

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 Performance Measurement, Part 4. (For Owners).

When monitoring and responding to the Contractor’s schedule performance on the project, how do you know if the schedule update is even valid for use?

For this post, we will address changes to Activity or Relationship Calendars.

Personally, the first schedule “quality check” I make is for complete logic. Please see the previous post, Schedule Performance Measurement, Part 2. (For Owners).

Next, I check for changes to Relationships and Relationship Lags. Please see the previous post, Schedule Performance Measurement, Part 3. (For Owners).

I then check for changes to Activity and Relationship Calendars and Calendar assignments.

When the Contractor is making schedule revisions to recover lost time for the update period, they may decide to work a crew more than the Activity or Relationship Calendar currently allows. If the Activity is assigned to a 5 Day Workweek with Holidays and Weather Days, they may decide to work 6 days a week for a specific resource to recover lost time. To be able to do this, they need to create an additional Calendar and set the work days up accordingly. They then replace the existing Calendar with the new Calendar. This allows the same amount of work, or Work Day Duration, to be scheduled over fewer Calendar Days. This results in shortening the Calendar Day Duration of the Activity Network(s) which contain the affected Activities.

This is the kind of schedule revision the Owner must be aware of and understand. It can be checked for in Primavera P6.

What Primavera P6 is not good at checking are changes to the work days in an existing Activity or Resource Calendar. As long as the Calendar Name does not change, P6 does not report it.

Most of us use third-party software designed to identify changes to Calendars. That’s great, but we still need to understand the impact of the changes identified.

Changes to Calendars and the Work Days in a specific Calendar do not make the schedule invalid for use. But, the owner needs to know what changes were made and what effect the changes have on the affected Logic Path(s).

That said, finding the changes to any Calendars, understanding the impact of the changes found, and reporting those findings is important to the Owner.

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 Performance Measurement, Part 2. (For Owners).

When monitoring and responding to the Contractor’s schedule performance on the project, how do you know if the schedule update is even valid for use?

For this post, we will address changes to the logic.

Personally, the first schedule “quality check” I make is for complete logic. The Primavera P6 schedule log provides a basic check. But I also use third party software that provides a more in-depth check for activities which may only have an SS relationship to their only successor activity. Sometimes, the check uncovers missing lag values or “reverse logic”. It may even uncover an SF relationship. All of these must be identified and addressed.

Often, when the Contractor is making schedule revisions to recover lost time for the update period, they make subtle changes to logic. As a Project Owner or CMa, we need to understand what was revised and why. If the relationship for an activity in the current or previous period Longest Path was changed from an FS relationship to an SS relationship, with or without a lag, to pull the scheduled Finish Date back, we need to understand that.

The same applies to the previous period or current update Near Critical Path(s).

If the contractor makes a logic revision for an activity which results in the only successor activity having an SS relationship, an open end is created. (There should have been an FS or FF relationship added to complete the logic). Otherwise, the finish of the activity does not drive anything in the schedule. This is an open end, (which does not show up on the Primavera P6 schedule log).

Any “open end” relationships make the schedule network logic incomplete. Sure, there are activities that once complete will not drive any other activity or work until the project is complete, if that is the case, they should be tied to Final Completion or whatever the last activity in the schedule is called. But more likely, the activity relationship was missed during development or when making revisions.

However, if this activity is supposed to drive other work, the relationships should model this. Not having complete logic for just one activity results in an erroneous schedule network. The activity could potentially be Critical or Near-Critical, but without the complete logic, there is nothing in the schedule to model the intended sequencing of the work for the affected network path. This means the Total Float values and scheduled dates for driven successor activities on this logic path are incorrect.

One of the basic checks and the first check I make is to verify the schedule network logic is complete. As an owner’s rep, we cannot know the detailed intent of the schedule sequencing, but we can identify open ends and any questionable logic we discover.

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. What Schedule Reports do you Need? (For Owners).

Do you receive a truckload of schedule reports each month from the contractor?

Do you actually look at or use them all?

Do you know there are many ways of looking at the schedule to be able to review progress, planned work, work that is slipping, or work that is Near Critical?

There are all kinds of reports the contractor can provide. But, it’s best if they know what you will need before they develop the Baseline Project Schedule.

When the contractor develops the schedule, they create groups of activity codes which they assign to activities to be able to filter, sort, and group activities in various ways.

They can assign phase, trade or responsibility, area, work type and many other code assignments.

The CPM schedule can be presented is a number of ways, but typically, we see an xer file, a schedule narrative, and a group of “layouts” in pdf format.

As the owner, you need to know what “layouts” to ask for!

Your specifications should at a minimum require a Critical Path layout with the Critical Path set to equal the Longest Path. I like to show the activity ID, Description, Physical and Duration Complete, Original, Remaining and AT Completion duration columns. Also, the Start, Finish, and Total Float columns. I like to group this by the project and sort on Start and then Finish Dates. This provides the “waterfall” view of the Critical Path. With the At Completion Duration column shown, I can see if there is any delay to any in-progress activities driving the Critical Path.

Your specifications should also at a minimum require a Total Float layout. I like to set this up to be grouped by the project, sorted on Total Float and then Start and then Finish. I show the same columns as I do for the Critical Path layout above. This provides a series of “waterfalls” based on Total Float values. For projects with multiple activity calendars, we cannot rely on the Total Float value to provide an accurate representation of the Near Critical Path(s) and subsequent network paths. But, it is very useful if you keep in mind what activity calendar the types of activities you are looking at typically have assigned. Knowing another network path is only a few days away from being Critical is, well, critical.

The classic layout grouped by WBS or some sort of activity coding is typical. This is the layout you get which shows the project phasing and deliverables broken down with the supporting activities. This is a necessary layout and is almost always provided by the contractor.

There are ways to format a layout to show activities taking longer than planned, not starting or finishing as planned, and planned to start or be underway in the next few weeks. These layouts are all helpful to the owner and the contractor.

Feel free to ask me about layouts I typically use. I’m happy to explain what I use and why.

As Planning and Schedule Professionals, we need to provide the Project Team with the “tools” they need to manage the project. The owner needs to know what presentations to require. We can help them.

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. 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. 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. 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. When the work continues and the schedule doesn’t… Or, “Which way did they go?”

person-question-300x300 There are times when the schedule update process gets side railed or thrown off course.

The problem comes when we don’t revise our baseline schedule and the work continues, at risk, with a disputed change order(s) and no approved revised baseline schedule to measure the pending change order against. How do we determine the change order impact? We know we need to use the most recent approved schedule. Is this the Project Baseline Schedule now? I’ve heard this argument many times.

Of course it is, it is the approved schedule at the time of the change order work insertion to create the fragnet to evaluate schedule impact. The approval of the “new” schedule which includes the changed work or delay deems it the “Revised” Baseline Schedule.

What happens to our schedule metrics and baseline cost or resource curve or projected budget cash flow? We have to revise those as well.

So, what happens when the work continues for a couple of reporting periods, the owner refuses to acknowledge change orders or delays and the schedule is reporting negative float / is behind schedule? The owner demands a recovery schedule, right? The contractor asserts they are delayed by the owner and need the change order finalized and added to the schedule to get back on schedule. Should the owner pay the contractor’s invoices when they’re behind schedule? Or hold retainage? Should the contractor stop work until the contract issue is settled? Or continue at risk creating the necessity of forensic claims analysis to resolve the unresolved change issues and delay conditions?

I believe that we, as planning and scheduling professional consultants, should strive to keep the project on course and ensure the entire project team understands the repercussions of not resolving the issues timely.

The question is: As consultants, how do we accomplish this?

We must always maintain our integrity and be honest with our client.

What has your experience been?

Have you kept updating the schedule, even while running deep into negative total float?

Do you advise your clients to force the settlement of overdue change orders?

Do you refer your client to a good Forensic Schedule Consultant you know?

Real scheduling is messy. But we all deal with issues all the time…..

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. Which Baseline Schedule is the Project Baseline?

Ideas All projects run into change orders and delays. We also need to measure and track progress against the original plan. Baseline Schedules are necessary for this.

But, how do we manage baseline schedules?

There are those that believe we always measure against the original baseline. This would be fine if the project never incurred a change order that changed the scope, worked out of sequence for whatever reason or suffered a delay of some kind.

The ugly truth is that no project or schedule is immune to change. As a planning and scheduling professional consultant, we see the proof of this all the time.

What does this mean for the Project Baseline Schedule?

Part of what we do, as a planning and scheduling professional consultant, is to help the contractor develop the Project Ideas Baseline Schedule. We also update and maintain the schedule over the life of the project

Each time the schedule is updated and accepted for use as the schedule update for the period, the updated schedule essentially becomes the “new” baseline schedule. This update represents the plan to execute the remaining work on the project and as such is now the “new” plan or baseline.

Sure, we can always refer back to the original project baseline schedule, but to what end?

If a change order is added to the work which significantly changes the scheduled work or a delay is allowed, we need to “re-baseline” the schedule. The team reviews and agrees to the “new” or “revised” baseline and we keep the project moving.

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