Project milestones measure progress and let you determine how well you are meeting your schedule. When your project continues to be on schedule, you can finish it on time and it is more likely to be on budget. Since milestones play such an important role in project success, they must have characteristics that allow you to observe whether key activities are finished. Writing such milestones into your project plan in an effective way lets you evaluate project status and take corrective action when necessary.


For your milestones, you have to choose events that take place on a specific date and that clearly mark the completion of a particular activity. Milestones are events that have zero duration and therefore occur on a single day. For example, closing the main breaker to connect the electrical system of a new building to the grid is a milestone showing the electrical installation is complete. Allowing parking on a newly paved lot means the paving is finished. Such milestones are specific to a single date and particular activity.


Milestones are easily observable. When you write your milestones into your project plan, you have to choose events that don't use resources for verification of the milestone. You can check, look up or verify a milestone, but it can't require an evaluation or calculation. A test procedure can't be a milestone, but if the procedure gives a result, such as a product that survives the test, the result can be a milestone.


The dates you attach to your milestones have to be realistic. You can base the milestones on your project schedule as long as it takes into account all the project activities and leaves enough time for each one. When you don't reach a milestone on time, you have to be able to determine why your reasonable assumptions about the schedule turned out to be wrong and what to do to fix the problem.


The most effective milestones are simple events that everyone connected to the project can see. When a client is checking on the situation of the project, clear milestones make it easy to demonstrate how you are progressing. When a team is working toward completion of critical activities, clear milestones serve to motivate them to meet their targets.


For milestones that give you clear information about the status of the whole project, those that form a sequence are the most effective. Choose them so that, when one is finished, you can go on to the next one. If they are not sequential, one at the end of the project may depend on one near the beginning, with other milestones in between. Choosing each one for an activity or group of activities that finish at about the same time lets you place the milestones progressively to mirror the work completed on the project.