Manage Project Task Dependencies and Relationships

Task dependencies allow you to designate a successor, or predecessor task for a task, and indicate the type of relationship for the tasks. You can create better project plans by using task dependencies and defining lag and lead time. Task relationships display in the Gantt chart in the Gantt view.
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Task dependencies allow you to designate a successor, or predecessor task for a task, and indicate the type of relationship for the tasks. You can create better project plans by using task dependencies and defining lag and lead time. Task relationships display in the Gantt chart in the Gantt view.
The following table describes the task dependency relationship types that you can define:
Gantt Bars
Description
Image describing the Finish to Start task dependency.
Finish-Start. The predecessor task must finish before the successor task can start. This dependency is the most common type.
Image describing the Start-to-start task dependency.
Start-Start. The predecessor task must start before the successor task can start.
Image describing the Start-to-finish task dependency.
Start-Finish. The predecessor task must start before the successor task can finish.
Image describing the Finish-to-finish task dependency.
Finish-Finish. The predecessor task must finish before the successor task can finish.
Task Dependencies and Autoschedule
You can auto-schedule to see the results of creating dependencies between tasks. Auto-schedule uses task dependencies to help determine a work sequence for the project.
Example
The Object Design task is required to be completed a day before the Object Integration task begins.
Drag and Drop Guidelines for the Gantt
In the Gantt view, drag-and-drop Gantt bars to create dependencies between tasks or to edit task dates. In the WBS, drag-and-drop tasks to move up or down in the hierarchy, or change the order of the tasks. The WBS is refreshed after you move or edit a task.
If pending edits exist, the options to drag bars to create dependencies, or move tasks in the WBS are unavailable. You can still move the task dates though.
  • Place your cursor near the start of a bar to change a task start date. The cursor changes to a left-right arrow. The finish date does not change.
  • Place your cursor in middle of a bar to change both the task start date and end date. The cursor changes to a four-way arrow. Both dates change by an equal amount.
  • Place your cursor near the end of a bar to change the task end date. The cursor changes to a left-right arrow. The start date does not change.
  • When you drop a bar after dragging, changes to the start and end dates are reflected in the WBS as pending edits.
  • A dependency line displays when you drag a bar up or down off a row. To cancel a change, press Escape while dragging, or drop the cursor into an open space without any task bars.
  • Save all pending edits before moving tasks, or creating task dependencies. Some toolbar options are unavailable if pending edits exist.
  • Move tasks into a new position in the WBS. Select the check boxes and then drag-and-drop them into the required place.
  • Select a row by clicking the check box next to the task.
  • Select and move a summary task to move all children tasks. The selected tasks are inserted before, or after the target task based upon the insertion line.
Create Task Dependencies
Create task dependencies in the same project from the Gantt view. When you link two tasks in the WBS, a finish-start dependency is created by default. The topmost task in the hierarchy sequence becomes the predecessor and the bottommost task the successor.
Drag-and-drop the Gantt bars to create any type of task dependency. Once created, you cannot change the dependencies using drag-and-drop, but can move tasks without affecting the dependency. To edit the task dependencies, use the task properties page.
You cannot create dependencies to and from summary tasks.
In the WBS, expand a collapsed summary task to view the dependency lines between its detail tasks and other tasks.
Follow these steps:
  1. Open the project.
  2. Open the Tasks menu and click Gantt.
    The Gantt view appears.
  3. Do one of the following:
    • In the WBS, select the check box next to the two tasks to create a dependency between them, and click the Link icon.
    • In the Gantt chart, grab the source taskbar and drag-and-drop it on the destination taskbar. Use the following guidelines:
      • Drag the right edge of the source taskbar and drop it on the left edge of the target taskbar. Creates a finish-start dependency.
      • Drag the left edge of the source taskbar and drop it on the right edge of the target taskbar. Creates a start-finish dependency.
      • Drag the left edge of the source taskbar and drop it on the left edge of the target taskbar. Creates a start-start dependency.
      • Drag the right edge of the source taskbar and drop it on the right edge of the target taskbar. Creates a finish-finish dependency.
Open Projects in Open Workbench
You can open any active projects you have rights to view or edit from 
Clarity PPM
. If you have the access rights to view or edit a project, open the project as read-only. Or, open as read/write from
Clarity PPM
 in Open Workbench. Format the projects in Open Workbench. If you have the read-only access rights to a project, or if the project is currently locked, you can open the project as read-only.
You cannot open projects with the same project ID and .rmp file name in Open Workbench from different 
Clarity PPM
 servers on your computer. To open a project under the conditions, delete the .rmp file you have saved locally. Then, try to open the project with the duplicate project ID from the other 
Clarity PPM
 servers.
Follow these steps:
  1. Open the project and click Tasks.
  2. From the Open in Scheduler menu, select Workbench.
  3. Select one of the following:
    • Read-Only. Opens the project unlocked in Open Workbench.
    • Read-Write. Opens the project in Open Workbench and locks the project in 
      Clarity PPM
      .
      Default:
      Read-Write
      If you have access rights only to view the project, or if another user locks the project, Read-Only is selected by default. The list box is unavailable in this case.
  4. Click Go.
    The project opens in Open Workbench.
Edit Task Dependencies
You can edit the task dependency relationship, such as predecessor or successor, the names of the dependent tasks, and so on. You can delete dependencies using the task dependencies page.
Follow these steps:
  1. Open the project and click Tasks.
  2. Click the name of the task to edit dependencies.
  3. Open the Properties menu, and from Main, click Dependencies.
    The task dependencies page appears.
  4. Click the link for the dependent task to edit.
    The task dependency properties page appears.
  5. Edit the following fields:
    • Relationship
      Defines the relationship between the current task and the task selected. To have the selected task precede the current task, select Predecessor. To have the selected task succeed the current task, select Successor.
      Values:
      Predecessor, Successor
      Default:
      Predecessor
    • Type
      Defines the type of relationship to set between two tasks.
      Values:
      • Finish-Start. The predecessor task requires finishing before the successor task can start. This dependency is the most common dependency type.
      • Start-Start. The predecessor task requires starting before the successor task can start.
      • Start-Finish. The predecessor task requires starting before the successor task can finish.
      • Finish-Finish. The predecessor task requires finishing before the successor task can finish.
      Default:
      Finish-Start
      Example:
      If you select predecessor as the relationship and Finish-Start as the type, the predecessor task is scheduled to finish before the successor task starts. Alternatively, if you select successor as the relationship, and Finish-Finish as the type, the successor task can finish once the predecessor task finishes.
    • Lag
      Identifies the lag period between the two tasks.
      Default:
      0.00
      Example:
      For a Finish-Start type of relationship, create a lag period of five days between the finish date of the predecessor task and the start of the successor task.
    • Lag Type
      Specifies the type of lag between two dependent tasks.
      Values:
      Daily or Percent
      Default:
      Daily
      Example:
      If you enter 5 as the lag and daily as the lag type, a lag period of five days between the tasks is created. Suppose, the duration specified is 100 days, 20 as the lag, and 20 percent as the lag type (20 percent of 100 days). A lag period of 20 days between the tasks is created. A lag time percent is based on the duration of the predecessor task.
  6. Save the changes.
Dependency Chains
A dependency chain is a relationship between multiple tasks or milestones. The dependency chain is created relative to the task or milestone positions in the work breakdown structure in the Gantt view. The type of dependency created is a finish-start dependency with zero lag. The next task or milestone in the chain relies on the completion of the previous task before it can start.
Example of finish-start dependency chain
Suppose, you have three tasks: Task 1, Task 2, and Task 3. Task 3 can start after completing Task 2, and Task 2 only after completing Task 1. You can create a dependency chain from Task 1 to Task 2, and from Task 2 to Task 3.
Create External Task Dependencies
You can create and change dependencies between tasks in different projects.
Follow these steps:
  1. Open the project and click Tasks.
  2. Click the name of the task.
  3. Open the Properties menu, and from Main, click Dependencies.
    The task dependencies page appears.
  4. Click New.
    The select task page appears.
  5. Click the button next to the task to create the external dependency, and click Next.
    The task dependency properties page appears.
  6. Complete the following fields:
    • Dependent Investment
      Displays the name of the project upon which the task depends.
    • Dependent Task
      Displays the name of the task upon which the task depends.
    • Relationship
      Defines the relationship between the current task and the task selected. To have the selected task precede the current task, select Predecessor. To have the selected task succeed the current task, select Successor.
      Values:
      Predecessor, Successor
      Default:
      Predecessor
    • Type
      Defines the type of relationship to set between two tasks.
      Values:
      • Finish-Start. The predecessor task requires finishing before the successor task can start. This dependency is the most common dependency type.
      • Start-Start. The predecessor task requires starting before the successor task can start.
      • Start-Finish. The predecessor task requires starting before the successor task can finish.
      • Finish-Finish. The predecessor task requires finishing before the successor task can finish.
      Default:
      Finish-Start
      Example:
      If you select predecessor as the relationship and Finish-Start as the type, the predecessor task is scheduled to finish before the successor task starts. Alternatively, if you select successor as the relationship, and Finish-Finish as the type, the successor task can finish once the predecessor task finishes.
    • Lag
      Identifies the lag period between the two tasks.
      Default:
      0.00
      Example:
      For a Finish-Start type of relationship, create a lag period of five days between the finish date of the predecessor task and the start of the successor task.
    • Lag Type
      Specifies the type of lag between two dependent tasks.
      Values:
      Daily or Percent
      Default:
      Daily
      Example:
      If you enter 5 as the lag and daily as the lag type, a lag period of five days between the tasks is created. Suppose, the duration specified is 100 days, 20 as the lag, and 20 percent as the lag type (20 percent of 100 days). A lag period of 20 days between the tasks is created. A lag time percent is based on the duration of the predecessor task.
  7. Save the changes.
Externally Dependent Tasks
The Gantt view displays externally dependent tasks. The dependent task is displayed before or after the task based on whether it is a predecessor or successor task. If multiple tasks are dependent on an external task, the list displays the first task out of the multiple that is dependent on the external task. The external project name is prefixed to the externally dependent task name.