Understanding Critical Path Management
While many project planning tools will calculate the critical path for you, you really need to understand what you are looking at in order to make the path from one side to the next as short (and dry) as possible.
The weather was beginning to cool and it was a great time to rent a cabin in the woods for the weekend. You made it to the cabin on Friday night and decided to go for a hike on Saturday morning.
You couldn’t wait! You started out first thing in the morning. The sky was blue, the air was crisp and the leaves crackled beneath your feet. You could hear water trickling in the distance and it grew louder with every step you took. You finally came upon the source of the sound. A beautiful river that ran right through the middle of your path!
What to do? It was too deep to wade across and too cold to swim. Then you saw your solution! A hundred feet up the river was a number or rocks that were jutting out of the water. They were close enough to jump from one to the next and spanned the entire length of the river. You jumped on the first rock, looked for the next biggest rock and jumped again. In no time at all you were across the river…slightly winded but dry!
There were choices to make along the way. There were smaller rocks that may have been a bit closer, but you chose the largest ones that would get you across the river the fastest. This was your Critical Path to get from one side of the river to the other side.
Transform this river into your current project. The rocks that enabled you to go from one side to the next are the phases, deliverables and milestones that make up your critical path.
Understanding Critical Path Management: Terms of Reference
There are a number of terms that are used when it comes to understanding the critical path method. The following are some of these terms:
- Critical Path: This is the longest list of sequenced activities that must occur on a project prior to it being complete. These activities have no float or slack time. This means if an activity that is on the critical path takes longer than expected then it will cause a delay in the delivery of the project.
- Earliest Start Date: This is the earliest date that an activity can be started. This will be dependent upon activities that are ahead of this particular activity. For example, you can’t put the icing on the cake until the cake has been baked and cooled.
- Earliest Finish Date: This is the earliest date that a task or activity can finish. For example, you can’t take the cake out of the oven until a certain amount of time has passed in order for it to be fully baked.
- Latest Start Date:This is the absolute latest date that an activity can begin without delaying the completion of the project. For example, if the cake above needs to be baked by 4:00 and it will take 3 hours to bake…it must be in the oven by no later than 1:00.
- Latest Finish Date: This is the absolute latest date a task or activity can finish without delaying the completion of the project. Again, in the cake example, it may take an hour to finish frosting the cake. If it needs to be done by 5:00, the latest it can finish baking is 4:00 in order to allow one hour of time for frosting.
- Float: This is the amount of time that an activity can be delayed without pushing the final schedule back. Items that are on the critical path have zero float.
- Non-Critical Path: These are the activities have a certain amount of Float time available to them. If this activity is delayed, your project can still finish on time.
Why is the Critical Path Management Important?
Usage of the critical path management method is important for a number of reasons. Primarily, you want your project to be completed in the shortest amount of time possible. You can compare it to using the stones to get across the river. You want to choose the shortest and most direct path from one side to the next. Likewise, you want to bring your project to completion in the shortest amount of time possible. The critical path method allows you to:
- Identify the Longest Pole: There may be a number of poles used to keep up a tent, but the longest one is the one that needs to be in the middle. All the other poles are secondary to the longest pole. The critical path method will let you identify which pole is the longest and allow you to focus in on making sure everything goes just right with those activities.
- Keep a Watch on Activities near the Critical Path:The critical path method will allow you to identify those items that will certainly cause a delay to your project. However, it also allows you to keep an eye on those activities that have minimal float time baked into them as well.For example, you could have a task that has only 5 days of float time. Something goes wrong with this particular task and the team struggles to get it done in time. Six days are burned up attempting to bring this activity to closure. You now have a new critical path as this particular task is now running behind with a “negative” float of 1 day.Knowing which activities are close to the critical path can be a topic for your weekly status meetings. One of the risks that could be discussed is whether one or many of these near-critical path items could indeed slip into the critical path. Then, come up with ways to minimize this risk from being realized as well as a plan to mitigate the impact if it does occur.
- Critical Path Management Allows for a Visual Representation of the Duration of the Project: Many programs that implement the critical path method create a network diagram. This will provide you with a visual representation of which activities lie on the critical path, which ones are close, and which ones are safely on the non-critical path.
What can you do if you don’t like the Critical Path?
You may not like what you see once you have scheduled your project using the critical path method. You may find that the project is going to run longer than the client would like to see. Or, there may be a show or event coming up where this project must be complete in order for your company to make a big impact. You have a couple of options.
- The first is that you can ‘crash’ your project schedule by adding more resources to the project. If it takes one person 8 hours to perform a task, you could have one more person join and cut the time down to 4 hours. This works well in certain situations and not so well in others. If it’s a routine project that just takes time to complete and no special training, then it works well.An example of this would be someone may work in the bindery of a print shop and throwing more people at a collating project can significantly reduce the time for completion. It doesn’t work so well in more technical projects where the time to bring someone else up to speed is longer than the actual time to finish the task.
- Another option is to fast-track the project. Use the critical path method to identify every possible instance where items on the critical path could perhaps overlap. It may not have to be a lot, but one item may be able to start just before the previous item ends. If you find you can do this for all the critical path tasks then you may find that you can shave off a considerable amount of time from the schedule.
So, enjoy your weekend in the cabin. You found the critical path to make it across the river and back. You can now do the same with the projects you manage and enjoy your week as well!
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