Schedule Terms & Processes – Construction and Schedule Management Services

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. Use the Work Breakdown Structure to Verify the Deliverables.

When the project baseline schedule is developed, activities are created that represent work to complete the project. It’s tempting to jump in and start adding activities as you build the project in your mind. Resist this temptation….

First, plan the schedule! How will the schedule be used? How will progress and performance be tracked? Will resource and cost be tracked by cost accounts? What presentation types are required by the contract?

What is going to be the approach to the project execution? Who are the team members? What are the contractual requirements for the schedule? Is there coordination with other work by contractors or the owner required?

Once you’ve answered these, and any other specific questions for the project execution, you should define the deliverable and break the deliverable down into smaller and smaller pieces until you have individual work packages. This helps ensure you get the entire scope of the project in the schedule.

Setting up your resources, cost accounts, activity coding and calendars is also part of the planning phase of developing the schedule.

Now you can start adding the activities to support the deliverables in an organized manner. The best part is this allows the use of mandatory logic for the completion of each work package. This makes it quick and simple.

Next, you can apply the preferential logic to create the phasing you planned earlier in the process. If you organized the WBS by phase, this is easily done as well.

Planning the schedule development and management will help ensure you end up with a complete schedule for the project. It will also make the schedule more useful and easier to manage.

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. What Data Columns Should be Displayed?

Do you ever look at a schedule pdf and wish you had access to more information? Know what the percent complete actually is? What produces the Total Float value?

Would you like to be able to see what is most important to you, as a PM? As an Owner? As a subcontractor?

When your contractor develops the project baseline schedule, they develop a few simple layouts for the project. (Or they should…) We typically set up a Classic Layout with Start, Finish, Percent Complete, Duration….

But we can also set up specific layouts for use by different team members.

However, often what you find in a progress or owner’s meeting is the two or three week look ahead schedule with the Activity ID, Name, % Complete, Duration, and Start & Finish dates. This doesn’t really offer much useful information.

I like to develop several layouts.

One layout that I use has the ID, Name, Physical % Complete, Duration % Complete, Original Duration, Remaining duration, At Completion duration, Start, Finish, and Total Float value. I can use these columns to see variances in duration usage and physical work completion. This quickly alerts me to production issues or potential delays. (It is possible to target previous updates and show actual variance values for duration, start and finish dates).

I also like to produce a simple progress update worksheet for the superintendent and field staff to use for keeping track of actual start and finish dates. They can keep these at their desk and mark off the dates as they happen each day. At the end of the month, all they have to do is add the physical % complete for the work still in progress. It’s just that simple. I provide a column for them to enter the date they now expect to finish the in-progress work. Using this expected finish date, we revise the remaining duration and the At Completion duration. This provides us with the Duration % Complete and the At Completion Duration variances which allow us to spot trends and take corrective action quickly.

Those are very simple layouts.

There are options for the Project Team. Let the scheduler show you what they can produce and work with them to find the right layouts with the right data columns that work for you. It will make managing work much easier for everyone.

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. Layouts and Options for Layouts.

Do you ever look at a schedule pdf and get lost in the many pages of data and bars?

Would you like to be able to quickly find out what is most important to you, as a PM? As an Owner? As a subcontractor?

When your contractor develops the project baseline schedule, they develop several activity code structures for the project. (Or they should…) We typically set up activity coding for phases, areas of work, subcontractor or trade responsibility, cost accounting source, CSI Division….

We do this so we can assign specific code values to each activity. This allows a filter or sort or group on specific or combinations of activity code values. We can filter by trade and sort by start. We can then group by area or phase or building. There are many ways to view the schedule which can make it easier for everyone.

However, often what you find in a progress or owner’s meeting is the two or three week look ahead schedule. This is a good tool. But, it is a specific tool. The look ahead schedule layout can show the work by phase or area or trade or simply as a “waterfall” by start date. The project team should decide what works best for them and request that layout for each meeting.

There are other layouts, in addition to the look ahead and the entire project schedule that are very useful.

One layout that I always use is the Critical Path (Longest Path) by Start/Finish date with no grouping. This provides a simple view of the critical activities by start date in a “waterfall” view. Very helpful for seeing what is critical and next in line.

I also like to produce a filtered list of incomplete and not-started activities sorted by Total Float value and then Start/Finish. No grouping, just a “waterfall” again. This allows us to see what is most likely the Near Critical Path activities by simply going down the list to the paths after the Critical Path. (I use a filter to remove the Longest Path) This is very helpful to the PM and Superintendent. They can ensure they focus on work that is near critical as well as critical. Too often this is missed.

Those are very simple layouts.

There are options for the Project Team. Let the scheduler show you what they can produce and work with them to find layouts that work for your project. It will make managing work much easier for everyone.

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. Spotting a Potential Resource Issue Early. Or, Why isn’t my Contractor Keeping up?

Question Would you like to be able to spot a potential contractor or subcontractor production shortfall early? Perhaps get ahead of the lagging work?

There are many ways to mine this info and establish the trend. I’ll offer a very simple method for P6 here.

If you set the percent complete type to physical, display the physical percent complete and the duration percent complete columns along with the start and finish date columns, you can spot potential production issues quickly when you update.

Personally, I like to run my cost based on my physical percent complete, but different project types require different methods….. But for this method, we will be basing the cost complete on the physical percent complete prorated over the entire duration.

Once you have the actual start date and physical percent complete you should enter the expected finish date to establish the revised scheduled finish date for the activity. Doing this will result in a different duration percent complete than the physical percent complete you entered based on actual work completed. The variance will show if the production rate for this work was accurate as actualized to date or if the actual production rate is better or worse than planned.

If the work is 50% physical complete and the adjustment to the scheduled finish date forces the duration percent complete to be 65%, you may want to investigate to find out if the original assumptions were incorrect or if this resource is adequate to meet the production as planned. If the same resource is having problems for several activities, there could be a trend that needs attention.

Simple. There are more accurate ways to measure this, such as resource man hours or units completed. But this is a quick, easy way to spot an issue just by looking at the schedule as you update or look over the schedule in a meeting…..

What other “easy” ways have you found to monitor the work and spot potential production issues?

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 Terms. What is the “Data Date”? What is “OOS”? What are “Lags”?

You are working with a construction scheduling consultant and they use terms you’ve heard before, but you’re not 100% sure you really understand what they mean. More importantly, you’re not sure how they affect the schedule.

Do not be ashamed, why should you have any in depth knowledge of yet another specialized function of the project management process? That’s why professional planning and scheduling consultants exist!

What is the “Data Date” and why do I care?

The data date is simply the “as-of” date used for progressing the periodic schedule update.

Typically, the data date is the end of the month, but I’ve seen it be the 15^th and the 25^th. Each schedule specification is different based on the owner’s requirements for reporting. Note: MS Project uses the term “Status Date”.

This is the date that all progress should be updated for progress up to. Everything after the data date is the pan to execute the remaining project activities. There should never be work in progress or incomplete with dates prior to the data date. I’ve seen this all too often with schedules run in MS Project because the person doing the schedule update does not understand this concept and how to adjust the settings to force incomplete work to move to the status date. It’s a simple fix for an experienced scheduler. Always look at your schedules and know the data date and verify all work prior to the data date is complete and all work after the data date shows no progress. Think of the data date as the starting off point for the rest of your project…. This is a necessary practice for construction scheduling.

What is “OOS” and why do I care?

OOS or Out-of-Sequence is simply a way of saying that work actually completed did not progress as scheduled.

Typically, this involves an activity that was scheduled to start immediately after the finish of it’s “predecessor” having actually started prior to it’s “predecessor” finishing. Other reasons may be work progressing much differently than scheduled or work being suspended for whatever reason.

Why do you care? You care because this logic is still driving any “successor” activities and is not correct based on how you actually completed the work. It affects all downstream work logically tied to the finish of the OOS work and does not model the remaining work correctly.

This can affect change order fragnet insertions, not produce correct total float values, and does not provide you with an accurate as-built schedule. Best practice is to correct the logic for OOS work immediately after updating the progress each period update. Most schedule consultants do this, but many do not and most PM’s and Superintendents do not. Many owners are not aware of the need to correct OOS relationships and do not require or enforce this practice. This is unfortunate. There are times y0u can leave some OOS relationships in place, but absolutely OOS work on the longest path or near critical path should be correct. Most construction scheduling consultants correct OOS relationships each schedule update.

What are “Lags” and why do I care?

Lags are like invisible activities added to the schedule; which typically separate start dates of successor activities by a set amount.

Depending on which calendars are assigned and the relationship selected, a current activity’s successor activity will start immediately after the finish of the current activity, if the relationship is a Finish-to-Start, FS relationship. Adding a lag of 3 to this relationship would force the start of the successor to wait 3 work periods until starting. Sometimes this is used for concrete curing time…… I prefer to use an activity for this so the time is transparent.

But typically, lags are used with Start-to –Start, SS relationships to allow work to be schedule concurrently. The lag forces the successor activity to wait set number of work periods after the start of the predecessor activity starts before starting. This models a plan to start one piece of work and then start successive work a set duration later. Such as finishing gypsum board wall sheathing before the entire area covered by the activity to hang the gypsum wallboard has completed. This is fine if this represents your plan to execute this work. Unfortunately, this is also how most PM’s and Superintendents choose to get the scheduled finish date back on time after the periodic update shows the project is behind schedule. This is still fine if the work can actually be executed this way, and it is the actual plan to “recover” lost time. It is just so darn easy to do, that many times it is used to appease the owner only and no plan is used to actually accomplish the work concurrently. This happens when the schedule is only part of the invoice process, and not an integral part of the project management process.

Don’t be afraid of lags, but the use of lags should be judicious and justifiable. There are many ways to model the logic to reduce the number of lags used. Typically, breaking the work into smaller pieces will allow the work to be scheduled without the use of lags.

Negative lags are bad idea and should be avoided or disallowed. There are many ways to make the logic work without the use of negative lags. Most schedule consultants stay away from negative lags.

MS Project shows lags and relationship types other than Finish-to-Start, FS in the predecessor and successor columns. Primavera P6 does not. Although it is not always easy to understand the effect a lag is having on the schedule, you should always be aware of their usage and understand the effect they have on the project schedule.

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