When you set constraints in a project plan, you essentially set time restrictions. Constraints put project phases within a specific time frame and can be set for milestones, activities and summary activities. Constraints on planning elements limit the flexibility of the project plan: the project planner or project manager cannot move planning elements along the timeline freely but need to plan within the timely constraints.

Before you set constraints, you should have established dependencies between your planning elements.

Article content

Set constraints on activities and summary activities

Set constraints on milestones

Overview: Types of constraints

Remove constraint

After you have created planning elements and established dependencies automatically or manually, follow these steps:

1. Open the Information window by double-clicking on a planning element in the Gantt chart or by right-clicking to open the context menu and then clicking on Edit.

2. Now you can edit all the details of the planning element.

3. In the Advanced tab, you can set the constraint of the planning element.

4. Select the type of constraint and then set the date and time.

In contrast to activities, milestones do not have a duration; nevertheless, you can constrain a milestone’s start or end date and/or time. This is done the same way as with activities. 

You can set different kinds of constraints on planning activities.

• Start as soon as possible – If you set this type of constraint, this planning element is set to start as soon as its predecessor is finished. This allows for maximum flexibility in your project plan.

• End date is as late as possible – Select As late as possible. This constraint is set when the latest possible end date for completion should be calculated from the end date of the whole project. 

• Start is on a specific date – If your planning element is supposed to start (activity) or happen (milestone) on a specific date, select Start - On. Then choose the date and time for the start of the planning activity. The activity will have to be started on this specific date, otherwise, you will be alerted to a constraint violation as you will see this symbol in your Gantt-chart. 

• Planning element must not start before a certain date – If you set this type of constraint, the planning element may only start on or after a certain date. Select Start - No earlier than. Then select the start date and time from the calendar. The planning element can be delayed into the future but may not be moved up earlier along the timeline. 

• Planning element must start no later than on a certain date – This type of constraint is useful if a planning element must start before a certain date. The planning element then needs to start on this date at the latest. Select Start - No later than and then choose the date and time from the calendar. 

• Planning element must be completed on a specific date – If a planning element needs to be finished on a specific date, select Finish - On. Then select the date and time from the calendar. This planning element may not be moved along the timeline and must not end earlier or later than on the set date. 

• Planning element must not be completed before a certain date – If you set this constraint, this planning element may be finished on or later than the set date. It must not be completed sooner, though. Select Finish - Not earlier than and then select the earliest possible date and time from the calendar. 

• Planning element must be completed on a specific date at the latest – With this type of constraint, the planning element must be completed as soon as possible but no later than on the set date. Its completion must not be delayed at all. Select Finish - No later than, then choose the latest possible date and time for the completion from the calendar. 

NOTE Constraints on single planning elements influence the whole project plan. It may be that you are not able to move planning elements freely along the timeline, due to constraints set on planning elements. If this is the case, InLoox alerts you to possible constraint violations with the symbol “constraint violation” in the planning list next to those planning elements that are affected.

TIP For better overview, it is advisable to show the column Constraint Type and Constraint Date in the planning list.

You can remove or change constraints that have been set:

1. Open the Information window of the planning element again and navigate to the Advanced tab.

2. Click on the small x in the right-hand side of the Constraint Type field to remove the constraint.

3. Then save your changes.