The scheduling of your tasks is driven by task duration, task dependencies, and constraints. It’s also driven by the project calendar. If your project calendar dictates that work is done Monday through Friday, 8:00 A.M. until 5:00 P.M., initially that’s when your tasks are scheduled.
Note
For more information about calendars, see the section titled Setting Your Project Calendar in Chapter 3.
However, if a task is assigned to a resource who works Saturday and Sunday, 9:00 A.M. until 9:00 P.M., the task is scheduled for those times instead. That is, the task is scheduled according to the assigned resource’s working times calendar rather than the project calendar.
Sometimes, you have a task that needs to be scheduled differently from the working times reflected in the project calendar or the assigned resource calendars. For example, you might have a task that specifies preventive maintenance on equipment at specified intervals. Or you might have a task being completed by a machine running 24 hours a day. In any case, the task has its own working time, and you want it to be scheduled according to that working time rather than the project or resource working time so it can accurately reflect what’s really happening with this task.
Note
Unlike project or resource calendars, which are essential to the accuracy of your schedule, task calendars are more of an optional scheduling feature. Create and apply task calendars only in those special situations when a task has its own unique schedule that tends to be independent of the project or assigned resource calendar.
To have a task scheduled according to its own working times, you must first set up the calendar. You can use or adapt a built-in base calendar, which is like a calendar template you can apply to the project as a whole, to resources, or in this case, to tasks. If the task’s working times are quite different from anything available in the existing base calendars, you can create your own.
Note
For specific procedures on modifying an existing base calendar, see the section titled Modifying a Base Calendar in Chapter 3. To create a new base calendar, see the section titled Creating a New Base Calendar in Chapter 3.
Note
When creating a base calendar to be used as a task calendar, give the new base calendar a specific name that indicates its role as a task calendar. This makes the differences among the base calendars very clear to you (and possibly other project managers) to prevent confusion and the application of the wrong calendars for the wrong purposes.
Note
If you have a set of tasks that are carried out entirely by equipment on the equipment’s own schedule, an alternative to creating a task calendar is to set up the equipment as a work resource. You can then apply a working times calendar to the equipment resource and assign the equipment resource to the appropriate tasks.
Note
For more information about creating work resources, see the section titled Adding Work Resources to the Project in Chapter 6.
To assign a base calendar to a task, follow these steps:
Select the task to which you want to assign a base calendar.
On the Standard toolbar, click Task Information and then click the Advanced tab.
In the Calendar box, click the name of the calendar you want to assign to this task. All base calendars are listed, including ones you have created yourself.
Click OK.
A task calendar icon appears in the Indicator column. If you rest your mouse pointer over the indicator, a ScreenTip displays the name of the assigned calendar (see Figure 5-23). Follow this same procedure to change to a different task calendar or to remove the task calendar.
Figure 5-23. Assign a calendar to a task to schedule it independently from the project or resource calendars.
Don’t confuse the task calendar with the Calendar view. A task calendar reflects working days and times for one or more selected tasks. The Calendar view is a graphical representation of tasks and durations in a monthly calendar format.
Note
For more information about the Calendar view, see the section titled Working with Graph Views in Chapter 4.
Troubleshooting
You assigned a task calendar, but it’s not scheduling tasks in all the times it should
The task probably also has a resource assigned, and the resource calendar is conflicting with what you want the task calendar to accomplish.
When you assign a task calendar, it takes the place of the project calendar. However, suppose resources are assigned to the task as well. Resources are all associated with their own resource calendars as well. Although a resource’s calendar might be the same as the project calendar, it can be customized for the resource’s specific working times.
When resources are assigned, the task is scheduled not just for the working times indicated in the task calendar. Instead, by default, Microsoft Project schedules the task according to the common working times between the task calendar and the resource calendar.
For example, suppose the 24-hour base calendar is assigned to a task that’s also assigned to a resource who works Friday through Sunday, 9:00 A.M. until 7:00 P.M. The only times the two calendars have in common are Friday through Sunday, 9:00 A.M. until 7:00 P.M., so by default, those are the only times when work will be scheduled for this task.
If you apply a task calendar to a task with a resource assigned, and there are few to no common working times between the task calendar and the resource calendar, an error message appears, as shown in Figure 5-24.
Figure 5-24. The Not Enough Common Working Time error message offers two suggestions for making sure your task is scheduled the way you want.
You can change the working times in the resource calendar to ensure enough common time. Or, you can change the working times in the task calendar. You might also remove the resource if that’s possible for the task.
If you want the resource calendar to be ignored on a task, open the Task Information dialog box for the task and click the Advanced tab. Select the Scheduling Ignores Resource Calendars check box.
Note
For more information about resource calendars, see the section titled Setting Working Times and Days Off for Work Resources in Chapter 6. For information about resource assignments, see the section titled Assigning Work Resources to Tasks in Chapter 7.