This guide is continued from Part 1 Project Constraints - what they are and how to use them.
WARNING! Project Constraints have a valid part to play in project planning, but they can also be created by mistake with dangerous knock on effects. Read this guide to MS Project constraints for project planners and project managers. What they are and how to use them and common mistakes.
Project Constraints can be useful and have a valid part to play in project planning. However, they can also be created by mistake with dangerous knock on effects.stakeholdermap.comIn Microsoft Project constraints can be used to create a link between a task and a particular date. By default all tasks are created with the Constraint type ‘As Soon As Possible’. This allows MS Project to schedule a task on the basis of its duration, resource(s) and dependencies, rather than against a particular date.
Constraints can be set in a few ways including:
MS Project and other project planning software is designed to carry out complex calculations that Project Managers used to have to do by hand. stakeholdermap.comThe idea is that you input:
The software will then calculate start and end dates and the critical path for the project.
The simple project plan below has a project start date of 12/11/2012 and an end date of 14/12/2012.
All of the tasks have finish to start relationships and there are no constraints. The problem is the launch day has to be on the 13/12/2012. The venue is already booked and the press releases have gone out. This should prompt the Project Manager to investigate legitimate ways to reduce timescales.
However, it can be tempting simply to force the plan to meet the deadline, by changing the start and end dates.
Here is an example:
Firstly the Project Manager changes the start date of Prepare for launch to 09/02/2010.
If they are using Project 2007 they will get a warning message.
If they continue the link to the tasks predecessor ‘Train users’ will be removed and in this case a ‘Start No Earlier’ than 09/02/2010 constraint is set.
Here the existence of the constraints is less of a problem than the fact that the Project Manager is attempting to force a task to start earlier than the finish of it's predecessor. This breaks the logic of the project plan. Unless the Project Manager takes some other legitimate action to shorten the timeline the deadline probably won’t be met. In addition the dependency between ‘Train users’ and ‘Prepare for launch’ has been lost, this means that even if the Project Manager found a legitimate way to reduce duration earlier in the plan the reduction would not be reflected in the start date of ‘Prepare for launch’.
I have seen numerous examples of project plans that are riddled with constraints. If you see this you should be concerned. stakeholdermap.comIt suggests that the Project Manager may have manually set start or finish dates for activities. This may be because they don't understand how to use Microsoft Project's automatic scheduling capabilities or perhaps they have attempted to force the plan to meet an impossible deadline.
This example is from a project plan produced by one of my clients.
Here the Project Manager copied and pasted tasks into Microsoft Project, causing a series of ‘Start No Earlier’ constraints to be set. The problem is that the tasks won’t respond to improvements in the schedule. stakeholdermap.comFor example ‘UAT prep’ is dependent on ‘Tester Training’ which has a planned duration of 2 days. If the client finds a way to reduce the time it takes to train the trainers from 2 days to 1 day then UAT prep could start earlier. However, because of the ‘Start No Earlier’ constraint ‘UAT prep’ will remain scheduled to start on 18/03/2010 and the improvement won’t impact the plan.
Jack Dahlgren has written a macro which removes all contraints in MS Project automatically, see Microsoft Project vba