Effective Use of MS Project Calendars
Posted: Sunday, November 16, 2008
by John Caulfield
Mouse Training Company
In Microsoft Project it is important to know how calendars are calculated t o ensure your project is completed according to your schedule requirements. Project uses calendars in conjunction with task dependencies to determine when resources are available to work and when tasks can be scheduled.
There are three types of calendars project calendars, resource calendars, and task calendars. These calendars can be adjusted to define working time for the entire project, resources and for tasks.
A base calendar defines the usual working and nonworking times designated in a resource or project calendar when Project should not schedule tasks because work should not be done. Nonworking time might include meal breaks, weekends, and national holidays. You can choose any base calendar to use as the project calendar or as the starting point for a resource calendar. Base calendar can also be applied to specific tasks.
The Standard base calendar reflects a traditional work schedule: Monday through Friday, 8:00 A.M. to 5:00 P.M., with an hour off for break.
There are additional calendars to reflect for example 24 Hour working. The 24 Hours base calendar shows a schedule with no nonworking time at all and is normally used in continuous processes or when resources and tasks are scheduled for different shift patterns
The project calendar defines the working and nonworking days and times for tasks and usually represents your organization's traditional working hours. Project uses this calendar to schedule tasks that don't have resources associated with them by default. The project calendar specifies when project work can occur. In this case, the Project calendar specifies that all days of the week are working days.
In our case study, the project calendar defines that work can occur only on weekdays, from 8:00 A.M. to 5:00 P.M.
Resource calendars ensure that work resources (people rooms and equipment) are scheduled only when they're available for work. Resource calendars affect a specific resource. Automatically, the working time settings in the resource calendar mirror the Standard base calendar. However, you can customize the resource calendar to show vacations for individual resources. Don't forget even a room might need a holiday and be unavailable whilst it is being cleaned or decorated.
When Project schedules, it uses the resource calendars to schedule the tasks that have resources assigned. For example, if a resource has a vacation specified, Project will not schedule the task for period of time.
Task calendars make it possible for tasks to occur independently of working times scheduled in standard or resource calendars
The scheduling of tasks is based on the working times established in the project calendar and the resource's associated resource calendar. If you were a gardener and the task was mowing the lawn the task might be scheduled to exclude a particular week when a party was being prepared and held in the garden. This tool allows scheduling tasks that can only be performed at certain times of day or at certain times of year, due to weather, regulations etc.
If you have applied a task calendar and additionally assigned resources to the task, the task is scheduled for the working times that the task calendar and resource calendars have in common. If you want to schedule the task by using only the task calendar there is an option in the task information to ignore resource calendars in calculating the task.
Key to understanding how project calculates its scheduling is understanding how these calendars relate to each other.
Imagine you have a five day task starting on Monday to deliver stock to all the restaurants in a group during the working day.
In the standard calendar however you have defined the Monday as a bank holiday. (Setup using Tools Chang Work Time and designating Monday as a non working day. This would mean that the task would start on Tuesday and finish the following Monday as Project's default settings assume a Monday to Friday working week with week ends non working.
If the resource you have chosen for the delivery task wants a personal holiday on Tuesday the task would only start on Wednesday and be completed the following Tuesday. In other words the complete story with project includes all exceptions in the standard calendar plus or minus changes in resource calendars.
Finally the task itself could have a calendar. A new calendar could be created for the task with a rule ensuring that no delivers should be scheduled for the on Fridays. In the first week of operation with Monday as a bank holiday, Tuesday a holiday for the resource. Wednesday would become the first working day, Thursday the second; With the Friday a holiday for the task and the week end off the task would only be completed the following Wednesday. In all subsequent weeks without the bank holiday it would be Tuesday.
So Project calculates the schedule according to the overall project calendar, resources calendars and calendars associated with the task itself.
A final layer of complexity can be introduced into the equation. If a task had duration of five days it would obey the schedule outlined above. However, if the task was instead enter as five elapsed days all holiday variations in standard, resource and task would be ignored and the task would revert to Monday to Friday working.
John Caulfield Mouse Trainer
http://www.mousetraining.co.uk
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Top-level comments on this article: (1 total)This was really useful. Thanks John for a good grounding on this subject. It has answered some questions I had
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