Most of us have used the 'Depart at' and 'Arrive by' feature on Google maps. You choose 'Depart at' when you don't really have the time pressure, and use 'Arrive by' when you have to reach by a fixed time or probably a little ahead. A meeting, maybe. "Arrive by" tells you the latest time you need to start to reach your destination on time. Project scheduling is no different from 'Depart at' and 'Arrive by'. We have all had that one project, which has a non-negotiable deadline (similar to arrive by).
In this blog, I would like to talk about scheduling a fixed deadline project and the trade offs/negotiations, should the project run into issues. I am using some learnings from the projects I have worked on and I will touch upon the important concepts of Project Duration and Critical Path (CP) but I won't dwell into the calculations surrounding them.
One might feel a little twitchy, should such a fixed deadline project come your way, but it is not as difficult as it may sound and can be used as an important learning exercise. A fixed deadline project presents challenges similar to that of any other project. What sets it apart is the set of trade offs/negotiations that come with it.
Lets cover some basics and show the steps required to build any project schedule (Fig 1).
Project Duration and Critical Path
For reverse planning, let's discuss Project Duration and CP a bit more in detail.
Project duration is the amount of time required to complete the scope of the project. You can either calculate project duration using the CP or without it. The choice is completely yours.
CP represents the minimum time necessary to complete the project, in other words the sum of estimates of all CP tasks determines the project duration. One might wonder why we need CP at all. Slippage or delay in finishing the CP tasks will definitely result in the project getting delayed and hence it is important to pay special attention to CP tasks. You will read about it in the last section.
Table 1.0 provides the tasks, their interdependency and respective estimates.
|Task||Requires (Dependency)||Estimate (days)|
Table 1.0: Task, Sequencing and Estimation
Let's assume the project deadline is 15/10 and today's date is 29/09. I won't dwell on how to calculate duration or to determine the CP. I did those calculations in the background and arrived at the following (also shown in table 2.0, for reference):
CP = A -> B -> D -> F -> G (Tasks with 0 slack). These tasks cannot be delayed without affecting the project duration.
Project Duration = 17 days (sum of estimates of CP tasks).
Tasks C and E have a slack of 2 and 6 days respectively.
I found this resource to be quite good in explaining how to do the above calculations.
Table 2.0: Task, Dependency, Critical Path, Slack etc
Project Start and Trade Off
As mentioned earlier, while working on a project that has a fixed deadline, the deadline is used to arrive at the start date. In our case, the deadline is 15/10 and that means our project should have started on 23/09 (Deadline - Project Duration, i.e, 15/10 - 17 working days). Today's date is 29/09 and that means we are 4 days behind (working days only). Now in the bigger and more complex project this difference can be significant. Of course, it is not always that the start date is a date in the past. Now as a project manager, you are entrusted with saving the project from slipping. In this scenario, here are some things you can do.
In Fast Tracking (FT), one analyzes the CP tasks and determines which of these tasks can be done parallelly and thereby reducing the overall project duration. FT is done for CP tasks that carry low risk. Reducing the duration of tasks that are NOT on CP will not result in reduction of project duration. Hence, to entertain any hope of saving the project, determine CP.
The CP tasks are analyzed to determine what are effects of reducing the duration of CP tasks and what kind of resourcing be required to meet this demand. In others. E.g Adding more FTEs for certain critical tasks and reducing the duration.
Negotiate reducing the scope by delivering the most important scope that delivers value. This requires a more in depth discussion.
You need to keep optimizing the project duration or CP, until you arrive at a start date that is in the future. Even after you start the project, there is a chance that your project will still slip, but it is important to remember that CP tasks cannot afford to be delayed and non-CP tasks should not get delayed beyond their respective slackr. Should this happen, you need to intervene. In addition to the above trade offs consider negotiations discussed in my earlier article.
If you have the benefit of an automated tool like MS Project, it can calculate the project duration and CP for you. Knowing how to use this data and devise a trade off/negotiation approach are the opportunities that these types of projects provide you with and help you hone your skills.