What Are Leads and Lags in Primavera P6 Version 8.2?

Project Planning and Control Using Oracle Primavera P6 - Version 8.2 EPPM WebUnderstanding Lags and Leads in Primavera P6 8.2

A Lag is a duration that is applied to a dependency to make the successor start or finish earlier or later.

  • A successor activity will start later when a positive Lag is assigned. Therefore, an activity requiring a 3-day delay between the finish of one activity and start of another will require a positive lag of 3 days.
  • Conversely, a lag may be negative when a new activity may be started before the predecessor activity is finished. This is called a Lead or Negative Lag.
  • Leads and Lags may be applied to any relationship type.
An example of a FS with positive lag:

positive lag in p6

positive lag in p6

An example of a FS with negative lag:
negative lag in p6

Here are some important points to understand about Lags in P6:

  • The lag duration is calculated on the lag as in Microsoft Project and other Primavera products. A lag is not assigned to one or both of the Predecessor and Successor activities as in Asta Powerproject.
  • Lags may be assigned one of four calendars from the Calendar for Scheduling Relationship lag drop down box in the General Schedule Options form. This form is opened by selecting Tools, Schedule… and clicking on the options tab.

The four Lag Calendar options are:

Ø  Predecessor Activity Calendar,

Ø  Successor Activity Calendar,

Ø  24-Hour Calendar, and

Ø  Project Default Calendar.

primavera p6 version 8-2 info button Lags are calculated by Primavera P3 and SureTrak software using the Predecessor Calendar. Microsoft Project 2003 to 2010 uses the Successor Calendar or may have an Elapsed Duration Lag. Earlier versions of Microsoft Project used the Project Calendar. Asta Powerproject assigns the lag to either or both the predecessor or successor thus allowing either the Predecessor or Successor Calendar to be selected for each relationship.
eh.com.au warning symbol You must be careful when using a lag to allow for delays such as curing concrete when the Lag Calendar is not a seven-day calendar. Because this type of activity lapses nonwork days, the activity could finish before Primavera calculated finish date.

You must be extremely careful when opening multiple projects when the Lag Calendar option is different for each project. This is because all the project options are changed permanently to be the same as the Default Project and therefore some of your projects may not calculate the same way as they did before opening the projects together. Please read the Multiple Project Scheduling chapter for more details on this topic.

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Setting Up Constraints in Primavera P6 Version 8.2

Project Planning and Control Using Oracle Primavera P6 - Version 8.2 EPPM WebConstraints in Primavera P6

Constraints are applied to Activities when relationships do not provide the required result and are often a result of External Dependencies.

Typical applications of a constraint are to constrain an activity to a date for:

  • The availability of a site to commence work.
  • The supply of information by a client.
  • The required finish date of a project.

Constraints are often entered against Milestone activities to represent contract dates and may be directly related to contract items using Notebook Topics.

Constraints are covered in detail in the Constraints chapter.

Understanding Relationships

There are four types of dependencies available in Primavera P6:

  • Finish-to-Start (FS) (also known as conventional)
  • Start-to-Start (SS)
  • Start-to-Finish (SF)
  • Finish-to-Finish (FF)

Two other terms you must understand are:

  • Predecessor, an activity that controls the start or finish of another immediate subsequent activity.
  • Successor, an activity where the start or finish depends on the start or finish of another immediately preceding activity.

The following pictures show how the dependencies appear graphically in the Bar Chart and Activity Network (also known as PERT, Network Diagram and Relationship Diagram Views):

The FS (or conventional) dependency looks like this:

contraints in primavera p6

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How to Add Relationships in Primavera P6 Version 8.2

Project Planning and Control Using Oracle Primavera P6 - Version 8.2 EPPM WebADDING RELATIONSHIPS IN PRIMAVERA P6

The next phase of a schedule is to add logic to the activities. There are two types of logic:

  • Relationships (Dependencies or Logic or Links between activities), and
  • Imposed Constraints to activity start or finish dates. These are covered in the Constraints chapter.

The Primavera Help file and other text use the terms Relationships and Logic for Relationships but do not use the terms Dependencies or Links.

We will look at the following techniques in this chapter:

Topic Notes for creating a SF Relationship
  • Graphically in the Bar Chart.
Drag the  mouse pointer from one activity to another to create a dependency.
  • By opening the Activity Details form.
Predecessor and Successors may be added and deleted from the Relationships, Predecessor or Successor tabs.
  • By editing or deleting a dependency using the Edit Relationship form.
Double-click an activity link in the Bar Chart or PERT View.
  • Opening the Assign Predecessor form or the Assign Successor form from the menu.
  • Select Edit, Assign, Predecessors…, or
  • Select Edit, Assign, Successors….
  • By displaying the Predecessor and/or Successor columns.
Double-clicking in the Predecessor or Successor cells will open the Assign Predecessor form and the Assign Successor form.
  • Chain Linking or Automatically Linking activities with a Finish-to-Start relationship.
Select the activities in the order they are to be linked using the Ctl key, right-click and select Link Activities.

Relationships

There are two types of dependencies that are discussed in scheduling:

  • Hard Logic, also referred to as Mandatory or Primary Logic, are dependencies that may not be avoided: for example, a footing excavation has to be prepared before concrete may be poured into it.
  • Soft Logic, also referred to as Sequencing Logic, Discretionary Logic, Preferred Logic, or Secondary Logic, ,may often be changed at a later date to reflect planning changes: for example, determining in which order the footing holes may be dug.

There is no simple method of documenting which is hard logic and which is soft logic as notes may not be attached to relationships. A schedule with a large amount of soft logic has the potential of becoming very difficult to maintain when the plan is changed. As a project progresses, soft logic converts to hard logic due to commitments and commencing activities.

Microsoft Project allows one relationship between two activities, SureTrak and P3 two relationships between two activities and P6 four relationships between two activities.

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How to Add and Delete a Curtain in Primavera P6

Adding and Deleting Curtains in Primavera P6

Primavera Version 5.0 introduced a function allowing the placing of multiple curtains on the Gantt Chart which may be all hidden or displayed. A Curtain, used to highlight periods of time over part of the bar chart, may be displayed in a similar way to P3 and SureTrak.Select View, Attachments to display the Curtain menu or right-click a bar and select Attachments, Curtain:

  • Add Curtain opens the Curtain Attachment form used to create a curtain,
  • Show All shows all the curtains,
  • Hide All hides all the curtains, and
  • Clicking on a curtain in the Gantt Chart also opens the Curtain Attachment form where individual curtains may be deleted or hidden.
  • Using the Start Date and Finish Date boxes, or
  • Grabbing the left or right edge of the Curtain in the Bar Chart (the cursor will change to a ) and dragging the start or finish date, or
  • Grabbing the Curtain in the center (the cursor will change to a ) and dragging the whole Curtain.
Project Planning and Control Using Oracle Primavera P6 - Version 8.2 EPPM Web

A curtain is deleted by double clicking on the curtain to open the Curtain Attachment form and clicking on the  button.

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How to Fix the Formatting Bars Issues in Primavera P6 8.2

Formatting Bars Issues in Primavera P6 8.2

There are a number of issues with the Primavera P6 standard bar formatting in version 8.2 that need to be understood so the user may display the activity bars logically:

Actual, Remaining Critical and Remaining Critical Bars

It is recommended that you use the Primavera default bar display options displaying the Actual Work (this bar is displayed from the Start date to the Data Date), Remaining Work and Critical Remaining Work bars (these bars are displayed from the Data Date to the Finish date with the appropriate filter).

This is because the Early bar will not display actual progress as in other software packages. Please read the Understanding Dates section in the Tracking Progress chapter to understand how the dates are calculated that are used to draw each bar.

Total Float Bar

The Total Float Bar is called the Float Bar in the Bars form which is inconsistent terminology.

By default a Total Float bar is displayed on a completed task, but the Float value is set to “Null” (which is displayed as a blank). It is not logical to display a float bar when there is no float value:

formatting total bar float in p6

  • To prevent this from happening you should edit the total Float Bar Filter in the Bars form so it is only displayed for Not Started or In Progress activities:

formatting bars in p6 8.2

formatting bars in p6 version 8.2

  • This is what it should look like now:

formatting bars in primavera p6

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Setting Up Activity Types and Milestones in Primavera P6 Version 8.2

Activity Types and Milestones in Primavera P6 Version 8.2

An Activity may be assigned one of the following default Activity Types using the drop down box in the Project Defaults tab:

  • Finish Milestone
  • Level of Effort
  • Resource Dependent
  • Start Milestone
  • Task Dependent
  • WBS Summary
Project Planning and Control Using Oracle Primavera P6 - Version 8.2 EPPM Web
TASK TYPE DESCRIPTION
  • Task Dependent
These Activity Types have a duration and will only calculate the duration using the assigned calendar even when one or more resources are assigned to an activity.
  • Resource Dependent
These Activity Types have a duration and will calculate the duration only using the calendar assigned to the activity when NO resources are assigned to the activity.

These activities acknowledge Resource Calendars when resources are assigned.

This is similar to an Independent Activity Type in P3 and SureTrak.

They acknowledge the Activity calendar to calculate the Early Start date.

  • Level of Effort – LOE
This Activity type is similar to P3 and SureTrak Hammock activities. It spans from the start or finish of one or more predecessor activities to the start or finish of one or more successor activities which are linked by relationships.
  • Start Milestone
A Start Milestone has a start date and no finish date and is scheduled at the start of a time period and may not be assigned Resources.
  • Finish Milestone
A Finish Milestone has a finish date, no start date and is scheduled at the end of a time period and may not be assigned Resources.

Changing a milestone from Start to Finish would not affect a schedule when all the tasks are on one calendar but would move the milestone from the start of a day to the finish of the previous day.

  • WBS Summary
This Activity type calculates in the same way as P3 and SureTrak WBS activities and they span all activities with the same WBS code, but without relationships that are used with LOEs.
primavera p6 version 8-2 info button A Milestone has zero duration and is used to mark the start or finish of a major event. Primavera differentiates between Start and Finish Milestones in the same way as P3 and SureTrak, where a Start Milestone has a start date and no finish date and a Finish Milestone has a finish date and no start date. This is unlike Microsoft Project, which only has one type of Milestone. Later versions of Microsoft Project allow milestones with durations.

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