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Ask the Experts: Applying Two Constraints on One Task

Adenor from Oakbrook, IL asks: I have a task in a schedule that must start after an unknown date and must end on a specific date. I’ve tried to enter a start and finish date on the task, but it doesn’t seem to be working for me. After the task starts, it’ll take nine days including weekends. How can Microsoft Project schedule this task for me?

Answer: Project can certainly do this for you. Let’s take your problem one step at a time.

First, the need for start and finish dates. Since you can’t enter both a start and a finish date on a task, you can enter a “start no earlier” date to push the task forward in time and deadline. This will give you the ability to start the task after some date in the future and have a target for the ending date of the task.

To enter these values and dates:

  1. Double click on the task.
  2. Select the Advanced tab.
  3. Enter the deadline date.
  4. Select the Start no Earlier than Constraint.
  5. Enter the constraint date. Choose a date sometime in the future when you think it might start.
  6. Click OK.

Figure 1 shows how it would look with both constraints applied to a task.

Figure 1. Setting a “start no earlier” date constraint.

Ask the Experts: Applying Two Constraints on One Task

In this example I’ve also changed the Gantt chart to show the start no earlier date below the Gantt bar for the task, the constraint type above, the finish date to the right, and the deadline date to the right of the deadline on the task.

To create this formatting, right-click on the Gantt bar for the task and select Format Bar, then select the settings you see in the form in Figure 2. Using this method you would make changes on a Gantt chart for a single task bar.

The deadline date was added by: Format | Bar styles | Deadline | Text (in the bottom part of the form) | Deadline | OK. This is a change that will affect all deadlines applied to this Gantt view.

If the date format isn’t what you would like, you can make changes in Format | Layout.

Figure 2. The Format Bar property dialog.

Ask the Experts: Applying Two Constraints on One Task

The second part of your question asks about showing the task as nine days in duration, including weekends. When duration is entered, the system looks at the project calendar and uses availability according to that calendar, usually set for business days, which doesn’t include weekends. This can be overridden so that the task will use the physical number of days — both working and non-working. This feature is called elapsed time. Enter the duration as “9 ed” instead of “9d” to have physical days counted. See the comparison example in Figure 3.

Figure 3. Entering an elapsed time to count physical days with “ed” instead of “d.”

Ask the Experts: Applying Two Constraints on One Task

When the task starts to execute, I would recommend entering the actual start date to see how it compares against the deadline date and moving it forward to reflect what actually occurred. Your goal will be to not let the end of the task cross the deadline.

My recommended steps for scheduling the task to fit your needs are:

  1. Enter a start no earlier constraint.
  2. Enter a deadline for the task.
  3. Enter the duration using elapsed time (9 ed) to get physical days.
  4. Enter the actual start date of the task.
  5. Make sure that the end of the task doesn’t cross the set deadline.

 

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3 Comments
  1. Is it possible to use a “finish date” from a task as a constraint date or deadline date for a second task?

    For example, Task A finishes.

    Task B must complete at the same time as Task A. Can I use a deadline to cause Task B to not be rescheduled past the Task A completion time?

    The issue I’m bumping into is that Task B has some predecessors and I need them to stack up against Task B. If all of the Task B predecessors are “complete as early as possible” then they start like a year too early (back at the start of the whole project).

    If Task B is anchored (if I specify a hard date, e.g. “must complete no later than 4/4/2020” and have the Task B predecessors “complete as late as possible” then they stack up nicely.

    But if I just make Task A a predecessor to Task B AND have the additional Task B predecessors be “complete as late as possible,” then Task B and it’s chain of predecessors (excluding Task A) are all pushed out to the end of the project in 2025…

    I’m trying to figure out how to cleanly have the Task B events auto schedule and shift based on Task A’s completion date.

    – Thank you.

    Reply
  2. Is it possible to have a Task A Start to finish with task B (B needs to finish before A starts), but at the same time Task A also needs to finish together with task C ?

    Reply
  3. Start to finish is typically used for planning projects from the ending date. linking Task A in a SF relationship with task b results in Task a starting before the project start date. Why not make task b be task A and then A becomes B. Link these in a FS relationship. Then link A & C in a FF relationship. Keep it simple!!!

    Reply

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