Construction Scheduling. Checking the CPM Schedule for Lags/Leads and Relationship Types.

In my previous post, I provided some basic schedule quality validation methods for use by project management professionals without access to, or proficiency with Primavera P6.

Continuing this area of discussion, this post will cover relationship lags, leads, and relationship types. This is a sore subject and there are typically many problems found in this area.

Again, when someone hands you the schedule update Gantt Chart, how do you know that the plan is valid? How can you do a quick validation of the schedule for basic requirements?

As I said before, a pdf of the schedule is nice for meetings, but someone from the owner’s and the contractor’s project teams needs to verify the schedule quality. The contractor usually has an in-house scheduler, so this is part of their processes during the development, update, and revision processes. What about contractors using a third-party planning and schedule professional? How do you validate our work? What about the owner and their construction management agency? How do they validate the schedule as presented by the contractor?

The owner and CMa will require the schedule in native format. That will allow their planning and schedule professionals to use the schedule program and verify schedule settings and structure. This is a must. I still see owners who simply look at the pdf and hope the schedule slippage will stop, one day….

Simply reviewing the schedule log generated by Primavera P6 will let you see the open relationships, out-of-sequence relationships, schedule settings, constraints, and other information.

You will not, however,  be able to find the relationship types and lags/leads used. One word of note here, I personally, do not use leads or negative lags. This is my preference. That said, you need to know how the logic is structured to know why it flows across the Gantt Chart layout the way it does. Just because the dates make sense does not mean that the logic is valid.

You can require the contractor provide you with a logic report from Primavera P6. This can be run sorted on activity ID. You can also have the predecessor and successor columns shown. The recent version of P6 will also show SS or FF relationship information, (with lag durations) much like MS Project does. Older versions of P6 do show relationships or lags/leads in the predecessor and successor columns. The logic report does. It just requires you to use the report as a legend while looking through the schedule layout to verify predecessors, successors and lags/leads used. This is very tedious, but this is a good practice. There are third party software programs that will produce reports only showing the activities with relationships other than FS. You can also produce this report in P6. But you must know how to do so…

The use of SS or FF relationships and limits for their us is a bit of a hot topic among planning and schedule professionals. Many organizations and government agencies include requirements in their schedule specifications limiting the use to a percentage of the total relationships. Many specifications do not speak to the use of relationships at all. I personally severely limit their use during development and only grudgingly use them when I do.

I avoid lags, but I do use them to push submittal development activities out to stagger the process. I do not use lags for concrete curing or other non-work activities which drive successor activity starts. These should be activities and transparent to all users of the schedule.

When reviewing the schedule for the use of SS, FF relationships and lags, simply make note of the usage and decide for yourself if the logic could be better modeled by breaking the activities into smaller areas or processes to allow the use of FS relationships. This is always the best approach. Review the use of lags the same way. If the activities can be broken down into more detail to allow the use of FS relationships for the work process, that is your best choice.

You can’t review or validate any of the information above if you don’t have the information in a format that allows you to analyze it. Require the P6 logic report or use third party software or learn how to find and analyze this information using P6 yourself. It is basic schedule mechanics, but the logic, relationships and activity durations are the backbone of the schedule. If the schedule isn’t developed following the project schedule specifications and schedule best practices, it is very doubtful the schedule will be a valid tool for the planning or control of the project performance and management.

These are just a couple of additional items that form the basics…. There are other items worthy of validating and I will speak to these in future posts.

I know many of you already know this information and can offer additional guidance and support, for all of us. 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. Checking the CPM Schedule for Complete Logic, Verifying the Use of Calendars, and Identifying Constraints.

When someone hands you the schedule update Gantt Chart pdf, how do you know that the plan is valid? How can you do a quick validation of the schedule for basic requirements?

First and foremost, a pdf of the schedule is nice for meetings, but someone from the owner’s and the contractor’s project teams needs to verify the schedule quality & validity. The contractor usually has an in-house scheduler, so this is part of their work during the development, update, and revision processes. What about contractors using a third-party planning and schedule professional? How do you validate our work? What about the owner and their construction management agency? How do they validate the schedule as presented by the contractor?

The owner and CMa will require the schedule in native format. That will allow their planning and schedule professionals to use the schedule program and verify schedule settings and structure. This is a must. I still see owners who simply look at the pdf and hope the schedule slippage will stop, one day….

Simply reviewing the schedule log generated by Primavera P6 will let you see the open relationships, out-of-sequence relationships, schedule settings, constraints, and other information. This report includes the most basic information you need.  You should receive and review this report!

If you only have one activity missing a predecessor and one missing a successor, you are OK. This doesn’t mean all the logic in the schedule is correct, that is a very subjective review. It just means you don’t have any open ends reported. You can still have activities with only start-to-start successor relationships, which is basically the same as having no successor relationship. But, you need third party software or the ability to use the program filter, sort and report features to ferret these out.

The out-of-sequence activities listed on this report simply tell you that the successor to these activities most likely started prior to the finish of the activity listed. There are other reasons the activity may be listed, but this is the most likely reason. Why does this matter? Because the logic continues to drive successor dates and correcting the logic ties to model the as-built progress allows the remaining work to model correctly. It also provides you with an as-built schedule, one day….. Require the contractor make corrections to remove all out-of-sequence activities from the schedule log. It’s not hard for them to do.

The schedule settings are typically listed in the schedule specifications. You can use the schedule log to verify several of these. Retained logic or progress override, total float computation, longest path definition, and predecessor calendar use are just a few of the settings which should be reviewed and verified.

The schedule log will also list activities with constraints applied. What it will not do is tell you if the project has a must finish by date applied at the project level. It will also not tell you what type of constraints, (or their dates) are applied to the activities. Again, you must use third party software programs that will report the constraints or you must know how to use the filters, sorting, and reporting functions of the program to see this information.

This schedule log is a very important tool and you should require it with each schedule submission.

What about calendars? How do you verify calendars are assigned? How do you verify the calendars assigned to activities use the correct work days, work hours, holidays? Again, third party software or manually going through the calendars for the project. You can require a pdf layout with the calendar column showing. This will at least let you verify there are calendars other than the default calendar in use.

These are just the basics…. There are other items worthy of validating and I will speak to these in future posts.

I know many of you already know this information and can offer additional guidance and support, for all of us. 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. Do You Manage Your Project with the Project Schedule?

QuestionWhy would you not use the schedule to manage the project?

If you put the effort into developing a detailed CPM schedule with input from the project team members, isn’t the schedule the best road map you have?

One of the great opportunities development of the baseline schedule offers is the project team’s review and input into the analysis of the scope of work for the project.

Depending on how your company estimates and proposes on projects, the people charged with executing the project after the award of the project to your company may have had limited to no involvement or exposure to the project requirements and the basic plan to execute the project based on the proposal.

The schedule development process encourages the project team to review the requirements, understand the sequencing of the work and sometimes even uncover an opportunity to improve on the initial proposed plan.

Assuming the project team has developed a great detailed baseline CPM schedule. I can’t imagine why anyone would not use the schedule to plan and manage work. Management likes to use the schedule to track and measure performance, but I consider the project schedule to be the project team’s best tool for executing the project.

Unfortunately, I run into projects that only produced the baseline schedule because it was required. The progress updates were used for invoice backup only and no effort was put into accurately updating and correcting out-of-sequence work and revising the plan to complete the remaining work in the project. Sadly, these projects do not have a valid schedule to base change order and delay impacts on. They also do not have an accurate idea of if or when the project will complete, much less what is required to get there.

There are many reasons to develop and use a detailed CPM schedule to manage the project. I can’t think of a good reason not to.

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