You are currently offline, waiting for your internet to reconnect

PRJ: How Elapsed Duration Tasks Affect Slack Calculations

Support for Office 2003 has ended

Microsoft ended support for Office 2003 on April 8, 2014. This change has affected your software updates and security options. Learn what this means for you and how to stay protected.

This article was previously published under Q87301
This article has been archived. It is offered "as is" and will no longer be updated.
Tasks with elapsed durations, rather than working durations, may introduceslack into a project because these tasks can extend into nonworkingportions of the project calendar.
Setting an elapsed duration on a task (for example, "1ed" as opposed to"1d") fixes the duration of the task in an absolute sense. An elapsedduration allows Project to extend the task into nonworking portions of theproject calendar. A "4eh" (4 elapsed hours) task that began at 2pm, forexample, would finish at 6pm without regard to the project calendar. Thismay result an unexpected amount of slack for some tasks.


NOTE: For this example, use the Standard project calendar.

  1. Create two tasks; task 1 with a duration of 8h, and task 2 with a duration of 9eh.
  2. Create a third task, task 3, with a duration of 1d.
  3. Set the project start date to 7/24/92 8am.
    Project 2010: On the Project tab, click Project Information.
    Project 98-2007: On the Project menu, click Project Information.

    Project 4.1 On the File menu, click Project Info.

    Project 4.0: On the File menu, click Summary Info.
  4. Make tasks 1 and 2 predecessors (FS) of task 3.
In this example, both tasks 1 and 2 start on 7/24 8am, and finish on 7/245pm; yet the Total Slack for task 1 is 0d, while the Total Slack for task 2is 2.63ed.

Because task 1 has a working duration of 8h, no portion of that task can bescheduled between 7/24 5pm (Friday) and 7/27 8am (Monday); hence, it has noslack.

However, task 2 has an elapsed duration of 9eh, and so could be scheduledto start as late as 7/28 11pm (Sunday) and still not delay task 3. TheTotal Slack is the difference between 8am Friday and 11pm Sunday, 2.63ed(63h).

Note that elapsed duration tasks are scheduled to start just as any othertask; that is, they are scheduled to start only during calendar workinghours. The elapsed duration implies only that the task can extend intononworking hours once having started. For task 2 to start between 5pmFriday and 8am Monday, it would have to be forced with either a Constraintor an Actual Start/Finish date.
CPM Critical Path

Article ID: 87301 - Last Review: 02/27/2014 21:04:46 - Revision: 5.0

Microsoft Project 98 Standard Edition, Microsoft Project 4.1 Standard Edition, Microsoft Project 1.0 Standard Edition, Microsoft Project 3.0 Standard Edition, Microsoft Project 4.0 Standard Edition, Microsoft Project 3.0 for Macintosh, Microsoft Project 4.0 for Macintosh, Microsoft Office Project Professional 2007, Microsoft Office Project Professional 2003, Microsoft Office Project Server 2007, Microsoft Office Project Server 2003, Microsoft Office Project Standard 2007, Microsoft Office Project Standard 2003, Microsoft Project 2000 Standard Edition, Microsoft Project 2002 Standard Edition, Microsoft Project 2002 Professional Edition, Microsoft Project Professional 2010, Microsoft Project Server 2002, Microsoft Project Server 2010, Microsoft Project Standard 2010

  • kbnosurvey kbarchive kbhowto kbusage KB87301