Schedule Development – Page 2 – Construction and Schedule Management Services

Construction Scheduling. Use of Relationship.

When your contractor develops the project baseline schedule, do they use many Start-to-Start (SS) or Finish-to-Finish (FF) relationships? Do you know?

A relationship determines how the successor activity will start or finish relative to the predecessor activity. The most common relationship is the Finish-to-Start (FS) relationship. The scheduled finish date for Activity A determines the scheduled start date for activity B. Unless a lag is assigned, this is simple. (See previous post).

However, often the schedule model requires the use of SS and/or FF relationships. If the activities will actually run concurrent and the activities are broken down to the level of detail necessary to plan and manage the work, this is acceptable. If the relationship includes the assignment of a lag, it may still be acceptable but this relationship should be reviewed and agreed to by all parties.

The problem arises when the series of work activities is developed with SS relationships and there are not any successors to the finish of these activities. These are essentially open ended relationships which means the activity could not finish and still not affect the schedule. This may indicate the work is not developed to enough detail to allow Finish-to-Start (FS) relationships to drive the work. Or the addition of work driven by the activity was missed during schedule development. If this work happens to fall on the Longest Path, this path is now driven only by the start of work for each activity, not by the finish of the work for the activity. In time, these relationships may fall on the Longest Path through updates and out-of-sequence work. personally, I prefer to limit the use of SS relationships in general.

Then there are the Finish-to-Finish (FF) relationships. These force the successor’s scheduled finish date to push out to follow the predecessor’s schedule finish date. This is commonly used to close off SS relationships to model concurrent work with the finish dependency. However, often the only successor is the FF relationship. This creates an open finish, which is much like a missing successor. If the predecessor has only the finish of the concurrent activity to drive, and this relationship is a FF relationship, and the successor has no other predecessor. It effectively has no predecessor to the start of this work. If the predecessor activity has only the successor with a FF relationship, what future work does it drive?

Finally, there is the combination of relationships that create reverse logic. Activity A is a FF to Activity B. Activity C is a SS to activity B. The duration of activity B determines when activity C can be scheduled to start. The start of activity B is not driven by any other work. The finish of activity B is driven by the finish of activity A. If the duration for activity B is increased, unless the start of activity C is driven by another predecessor relationship, the start date for activity C is pulled back to schedule an earlier start. This can have unintended consequences for the schedule. We see this often when the schedule is developed using a lot of SS and FF relationships.

We won’t mention the Start-to-Finish (SF) relationship. This is extremely rare. This says that the start of a predecessor cannot start until the finish of the successor. I have only seen it used intentionally and with an acceptable reason twice. And that was to model work on a rolling wave schedule for which there was not much design detail developed. However, this relationship is sometimes used by mistake.

The SS or FF relationship, if used correctly, can allow the schedule to model the plan. It is my opinion that the use of these relationships should be kept to the absolute minimum and be only used to model actual planned concurrent work which is broken down into the level of detail necessary to plan and control the work.

I know many of you can offer additional comments and recommendations. I welcome your comments and input. My goal, as always, is to help our industry and help the projects we support….

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. Use of Relationship Lags.

When your contractor develops the project baseline schedule, do they use many relationship lags? Do you know?

A relationship lag is an imposed period of time between the predecessor and successor activity. A common use in a Start-to-Start (SS) relationship with a 2-day lag. Perhaps the contractor’s plan is to start finishing drywall 2 days after the drywall installation begins. This allows the work to run concurrently.

There absolutely are times when work can and should be modeled this way. However, care should be taken to ensure an open start isn’t inadvertently created. (This is a future topic)

The problem arises when the series of work activities is developed with SS relationships with an assigned lag. This may indicate the work is not developed to enough detail to allow Finish-to-Start (FS) relationships to drive the work. The issue is, once the start of the predecessor is actualized, the start of the successor is only dependent on the calendar set for use for lags. This may not match the number of days intended. If this work happens to fall on the Longest Path, this path is now driven by a calendar. I prefer to limit the use of SS relationships in general, much less with assigned an assigned lag.

Then there are the Finish-to-Finish (FF) relationships with lags. These allow the successor work to finish only after the predecessor’s finish date plus the lag duration. This is commonly used to close off SS relationships to model concurrent work with the finish dependency. However, often the only successor is the FF relationship with the lag. This creates an issue in itself. (This is a future topic)

The most serious issue is when the relationship is an FS with a lag. What does the lag model? Should there be an activity to establish this difference in the relationship finish to start? Most likely, the answer is yes. There is nothing wrong in using an FS with a lag to have the lag represent say, cure concrete. I personally prefer to add the cure concrete activity with the number of days required. This is more transparent. The lag is not visible and creates a non-work period seen in the Gantt Chart bars and can cause confusion.

Then there is the negative lag, or leads. Many schedulers like negative lags and use them as a viable way to model the plan. When I see an FS relationship with a negative lag, I wonder why the use of a SS relationship with a positive lag could not have been used. The use of the negative lag may better represent the thought that the successor cannot start until 3 days prior to the finish of the predecessor. And this 3 days is the critical period. I personally prefer to model this type of plan with a SS with a lag or to further break down the activities to allow the use of FS relationships to model the work.

Finally, there are the SS relationships with an assigned lag that is larger than the activity duration forcing the model to show the work as an FS relationship. Why not just use the FS relationship? Unless there is a reason to model the work this way, it just doesn’t make sense to do so.

The relationship lag, if used correctly, can allow the schedule to model the plan. It is my opinion that the use of lags should be kept to the absolute minimum and only used to model SS or FF relationships.

But remember, the lag follows the calendar set for use for lag calculation. If the predecessor calendar is set for use, and the predecessor is assigned to a 5-day work week calendar, the lag will follow that calendar and the duration will be in work days. So, a 3-day lag could become a 5-day delay between the relationships if the lag spans a weekend. This may not have been the case when project work was planned and the schedule was developed and the lag did not span a weekend. Remember, this is not transparent, only someone who understands the schedule software and has access to the native file format can verify this. Unless the schedule layout includes the columns which show relationships with lags and the column that shows calendars. Even then, you need to know what the actual non-work days for the specific calendar are.

I know many of you can offer additional comments and recommendations. I welcome your comments and input. My goal, as always, is to help our industry and help the projects we support….

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. Resource and Cost Loading the Schedule

person-question-300x300 Once you have the basic CPM schedule development completed and you’re ready to start resource and cost loading, do you find the schedule specifications lacking in requirements or guidance for this part of the schedule development?

Some schedule requirements simply do not require resource or cost loading. Some require the assignment of resources but do not speak to cost. Some allow simple lump sum cost loading, some require unit pricing with equipment and material costs broken out.

Whatever the case, most of us prefer the schedule be cost loaded, at least the baseline schedule. This allows us to create the performance measurement cost curve for EVMS and the early and late cost curves many of us are familiar with and most specifications require.

Each planning and schedule professional will have their own preferences for resource and cost loading the schedule.

Myself, when a lack of requirements allows, I prefer the resource and cost loading be kept simple. Unless the payment process for the project is based on unit prices and crew pricing, I avoid unit pricing with equipment and material costs broken out. I work mostly in mid-size construction projects and find that lump sum cost loading works just fine.

One thing I prefer is to keep my percent complete type set to physical and make the cost percent complete equal the physical percent complete. I find this works well if the delivery of large equipment is cost loaded and work activities are assigned cost which includes labor, equipment and basic materials. Simple to develop, manage, understand and track. Remember, this is for general construction. Road, UG infrastructure, and other linear unit driven schedules will benefit from unit pricing.

I also like to assign a resource for each subcontract, even though I lump-sum cost load. This allows a resource or cost curve for each. This helps with resource level analysis.

I believe resource and cost loading of schedules is an underserved discussion topic and our industry as a whole would benefit from learning how various industries and project types approach this process.

Hopefully, this post will help start some dialogue among us.

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. Problems Modifying header and footer variables in Primavera P6 version 15.2?

CPM Consultant Professional Project Management — Project Management

It seems that there is an issue with Primavera P6 version 15.2 that makes it “impossible” to modify the variables for the header and footer sections.

This had me stumped too. But I found a work- around.

You can still add the variables by selecting modify and typing in the variable you want. Such as [cd] for current date or [filter_list] for the filters used or [project_name] for the project name…. There are commands for most all of the variables. I don’t have a complete list, but the common variables I use for most layouts is listed below.

Data Date: [data_date]

Project ID: [project_id]

Project Name: [project_name]

Layout Name: [layout_name]

Filter List: [filter_list]

Current Date: [cd]

Page: [page_number]

Pages: [total_pages]

What other methods have you found to work around this issue?

Does anyone have the full list of commands?

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. Are you Including the Complete Project Scope in the Schedule?

person-question-300x300 When you begin the planning for your project schedule, are you defining the project scope and breaking it down into work packages? Do you ever discover that work may have been missed if you had not completed this exercise?

You are not alone.

It’s just so easy to take off and start building the activities to build the project. It’s already in our head and all we need to do is get that plan on paper. Right?

I’ve found that even for a simple project, it makes the schedule development much more effective if the project team goes through the process of breaking the project down into the basic work packages and cross checking with the bid documents. This is often when we discover some piece of the scope is not included in any bid package. It happens….

This is why planning is a very important part of the schedule development. During the planning process, the work packages are developed, the sequencing of the work package delivery is worked out, the coordination of the work package execution is worked out… The list goes on…

I like to work through the planning process and then develop the WBS for the project schedule. This helps me determine how to develop the activities that create the deliverable work package and also helps with the preferential logic to coordinate work packages and resource usage.

The planning process is also a good place to develop the project calendars, activity coding, and resources. I like having these in place before I start developing the activities. It makes it easier to make the assignments as I go and keep the momentum of developing the work flow going. Having to stop and create a calendar or activity code breaks my flow. I also hate going back and trying to make calendar or code assignments after all the activities are developed. Some activity coding is simple to assign, but activity coding for responsibility, area, level, or CSI is more difficult to go back and add. That’s my story and I’m sticking to it.

The process of sequencing the activities and assigning the durations is easier for me then too. I can compare similar work through the use of activity coding. I can also use the resources I assigned early to make cost loading easier.

What other methods have you found to plan and develop your project schedules?

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. Are you using Calendars Appropriately in Your Project Schedules?

excalmation-mark Do you understand the need to develop specific activity, resource and project calendars? So you put the effort into this process? Do you understand how calendars can help you?

Many, many smaller projects have project schedules with calendars that are set to whatever the default calendar setting is. Typically, this is a 5 day work week calendar with 8 hour work days.

You may ask, what is wrong with this?

Well, the short answer is, you are not allowing your schedule program to effectively schedule the work for you. You should really have a calendar for each different work week, such as a 4-10 hour day calendar, (if you have a resource working this shift). A 7 day work week calendar with no holidays is very helpful for project milestones because the total float is in calendar days. A typical work week calendar with defined holidays and anticipated weather related non-work days is a great way to ensure weather sensitive activities have anticipated “weather days” assigned.

For this post, I will only talk about activity calendars. Resource calendars can add complexity, and must be addressed, but not in this post…

For activity development, I prefer to keep things simple. I use the appropriate calendar, based on the planned work week for the work tasks. This includes holidays and any other don-work days identified in the contract. I develop a weather day calendar, based on the appropriate normal work week calendar to assign to my weather sensitive activities. I use a 7 work day week calendar, with no holidays or any other non-work days for my contract milestones and as the default for the project. This allows the team to see calendar day total float values.

Of course, the use of multiple calendars creates a little confusion when reviewing the schedule. The total float values for a string of activities will be different based on the calendars assigned. The actual start date to finish date durations will not match the “work day” duration assigned. These types of issues confuse many people. But once you use the calendars appropriately, you are letting the schedule better model your plan for the work.

Isn’t this what the schedule is supposed to be used for at its’ most basic level?

What other methods have you found to model and manage work with calendars?

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 is a Project Schedule Worth to You?

Question My early construction schedule experience was gained while working on the owner’s side of the project. The issues I was concerned with were simple. Is the contractor on schedule? Will the contractor finish by contract completion? Have I delayed the contractor, and if so by how much?

Pretty basic concerns.

As time went on, and I learned from my many mentors, I found that a project schedule is an indispensable tool for managing the project. What better way to manage resources, project cash flow, spot trends in schedule slippage, and manage change order delay claims.

I now know these three things.

Project planning and schedule development are critical to the usefulness of the project schedule for managing the work. Garbage in / garbage out.
Maintaining the schedule through accurate updates, revisions to reflect the plan going forward, and the timely inclusion of delays or change orders is essential.
There will always be those that resist the use of a CPM schedule and those that believe it is the only tool available.

Where do you fall?

Do you believe the schedule is a necessary tool for payment or to meet the contract requirements?

Do you believe the schedule helps with managing the work and projecting your plan going forward?

Do you believe that adherence to the baseline schedule is paramount and no revisions or deviations from this plan are acceptable?

What value do you place on the project schedule?

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.

Paul Epperson CCM, PMP, PSP, PMI-SP

Construction Scheduling. How do we Incorporate the Subcontractor’s Schedule in our Baseline Schedule Development Process?

Road sign As construction scheduling professionals, we’ve all developed project baseline schedules. We’ve also worked with our subcontractors to get their input for the schedule, often with less than stellar results…..

This seems to a common problem. Continue reading “Construction Scheduling. How do we Incorporate the Subcontractor’s Schedule in our Baseline Schedule Development Process?”

Construction Scheduling. Why do some Construction Projects seem to fall Behind Schedule Immediately after NTP?

stop-go-signs-wrong-colors As construction scheduling professionals, we’ve all worked on smaller construction projects which have fallen behind schedule almost immediately after NTP.

This seems to be a common problem for smaller construction projects.

It seems that owners are expecting contract durations based on best case production scenarios. Who can blame them? They know that similar projects have been completed within these durations.

If this is so, why do many contractors fall behind schedule almost immediately after NTP? Continue reading “Construction Scheduling. Why do some Construction Projects seem to fall Behind Schedule Immediately after NTP?”

Schedule Management. How should a Non-Schedule Savvy PM or Superintendent Manage their Project Schedule?

Tilt Up You have created your project’s baseline schedule and now you are starting the schedule management phase of the project. What do you do?

If you have not done so already, you need to establish a “schedule log”. I like to start my schedule log when I start development of the baseline schedule. This allows me to track my revisions and reasons for making them. The schedule log provides you with historic data for each revision or update to the schedule. Very handy.

If you have not done so already, set up schedule layouts and filters you plan to use. I also set these up during me schedule development, but often times the owner decides they want to use something other than what the schedule specifications require.

Each periodic update, save your schedule with progress only. This allows you to see what the progress update did to your schedule, save this snapshot. Then make any revisions to correct out-of-sequence, OOS relationships and model the revised plan to finish on schedule. You now have your updated and revised schedule ready for use.

Update the schedule periodically. Compare your progress with the most current previously accepted schedule and the baseline schedule. Look at how you’re tracking, how your actual durations are comparing to your scheduled original durations, and how your work sequence is actually progressing. Identify problem areas and trends and develop corrective action to recover time lost.

After you update the progress for your schedule, revise the schedule update to reflect your actual plan for execution. This doesn’t mean a complete change of sequence or addition of new work. This is simply to model adjustments you are going to need to make to maintain the scheduled completion date.

Major revisions to the schedule to dramatically re-sequence work or add/delete large pieces of work are handled differently. This will be part of a future post.

Managing the simple month to month schedule update process is pretty straightforward. Correcting the OOS is more involved and care should be taken to follow best practices. This is all part of the basic schedule management process.

However, when in doubt, seek out the advice of a professional planner and scheduler.

Please visit https://conschmanservices.com to learn more about basic schedule concepts.

Please visit my LinkedIn account to learn more about me.

Paul Epperson CCM, PMP, PSP, PMI-SP