The schedule for a project and WBS elements refers to the start
date, finish date, and duration information. In a WBS structure, the schedule
for parent elements is determined by the schedule of the child elements.
Schedule fields
To specify a schedule, you need to
enter any two of the schedule fields; the third field is calculated and displayed:
- If you enter the start date and duration, the finish date is calculated
and displayed.
- If you enter the finish date and duration, the start date is calculated
and displayed.
- If you enter the start date and finish date, the duration is calculated
and displayed.
When you modify a schedule fields, the dependent field is recalculated
as described below:
- If you modify the start date to an earlier start date, the duration is
increased. If you modify the start date to a later start date, the duration
is decreased. The finish date is not affected by either of these changes.
- If you modify the finish date to an earlier finish date, the duration
is decreased. If you modify the finish date to a later finish date, the duration
is increased. The start date is not affected by either of these changes.
- If you increase the duration, the finish date is postponed to a later
date to accommodate the new duration. If you decrease the duration, the finish
date is brought forward to an earlier date to match the new duration.
Default schedule
When you create a new element (project
or WBS), a default schedule is created for it.
- If the new element is a root element, for example, a new project or program
that currently has no child elements, the default schedule is based on the
system dates. The start date is the current date, and the duration is one
day. The finish date is the same as the start date.
- If the new element is a child element of an existing element, the default
schedule is based on the parent element.
- If the start date of the parent element is the current date or later than
the current date, the default start date of the child element is inherited
from the parent. The start date of the child element is the start date of
the parent element, and the duration is one day.
- If the start date of the parent element is earlier than the current date,
the default start date for the child element is the current date, and the
duration is one day. The finish date is the same as the start date.
Modification of the default schedule
To create a
schedule, you need to modify the default schedule and enter your own start
and finish dates, and duration for the elements.
When you add a child
element to an existing element, the parent element schedule fields are disabled,
and you cannot modify the parent schedule fields directly. The schedule of
the parent is aggregated from the schedule of the child elements.
- Project schedule and effort is aggregated from its child elements - iteration,
summary task, change request, issue, defect, task, and milestone.
- Iteration schedule and effort is aggregated from its child elements -
summary task, change request, issue, defect, task, and milestone.
- Summary task schedule and effort is aggregated from its child elements
- task, change request, issue, and defect.
- Change request schedule and effort is aggregated from its child elements
- defect, issue, and task.
- Issue schedule and effort is aggregated from its child tasks.
- Defect schedule and effort is aggregated from its child tasks.
The rules for the calculation of the schedule fields for a parent
element are:
- The start date of the parent is the start date of the earliest scheduled
child element.
- The finish date of the parent is the finish date of the latest scheduled
child element.
- The duration of the parent is the available working days (as specified
in the project calendar) between the start and finish dates that are aggregated
from the child elements.
To modify the schedule of a parent element, you must modify the
schedule of its child elements. Any change that you make in the schedule of
a child element is aggregated to the parent element, and the parent element
schedule is modified to reflect those changes.
When you modify the
schedule of a task that has dependencies, the change is accepted only if it
does not affect the schedule constraints of the dependent tasks. For example,
assume Task A is dependent on Task B, Task B is dependent on Task C, and Task
C is dependent on Task D. All the dependencies are Finish-to-Start, and Task
D has a Finish no later than constraint. You modify the start date of Task
A so that task D cannot complete by the schedule constraint date. You are
prompted that the date change of Task A breaks the constraint
on Task D, and you have the following choices:
- Continue with the date change and automatically remove the constraint
- If you select this option, the start date of Task A is changed and the constraint
on Task D is removed.
- Keep the constraint and do not accept the date change - If you select
this option, no changes are made. The start date of Task A is not changed,
nor is the constraint on Task D removed.
Example 1: Calculation of a project schedule
Based
on the aggregation rules, the schedule for a project is calculated as given
below:
- The start date of the project is the start date of the earliest scheduled
project element.
- The finish date of the project is the end date of the latest scheduled
project element.
- The duration is calculated based on the available working days (as specified
in the project calendar) between the project start and finish dates.
Example 2: Calculation of a summary task schedule and
effort
Based on the aggregation rules, the schedule for a summary
task is calculated as given below:
- The start date of the summary task is the start date of its earliest scheduled
child element.
- The finish date of the summary task is the end date of its latest scheduled
child element.
- The duration is calculated based on the available working days (as specified
in the project calendar) between the summary task start and finish dates.