PRINCE2 Activity Planning Part 2
PRINCE2 Activity networking and precedence networks
PRINCE2 covers the basic concepts to help you draw up a simple network and Gantt charts if you are not already familiar with the techniques.
Activities have dependencies, just like products. You cannot test the new machine until you build it. Although Gantt charts are great, they do not show dependencies very well.
Most computer tools display arrows on the Gantt charts to try to show dependencies, but the arrows just make the chart confusing. A different diagram is much more powerful and suited to the job – The network diagram.
There are two basic sorts of activity networks but the most used one is the precedence network which is much more straightforward than the alternative, and all of the popular software tools use it.
The good news is that constructing a precedence networks is really easy and not as hard as most people think. This diagram simply shows in what order you can to the activities as well as being able to see that you can do some activities at the same time and the dependencies show that as well.
The precedence networks can show timings and this is where the real power of the technique starts to emerge. Products do not have the time as such, but rather the activities to build that product take time.
In putting the times into the network, you can work out the total time that the project requires.
The major technique used here is called critical path analysis (CPA) where the critical path is the longest path through the project and therefore sets the project’s earliest finish date. The technique determines which tasks are critical and contribute to the project end date, and those which have float or slack – Which simply means that they have some free time where their duration may take slightly longer yet it does not impact the end date of the project.
Activities with Gantt charts
After you have got the precedence network together, constructing a Gantt chart is very easy and you will most likely use a planning tool where you only need to enter the task names of all of the activities along with their durations and then link directly to the computer screen to set their dependencies.
Using such a tool, you can easily add the relevant resources whether they human or non-human to each of the activities making sure that the amount of work effort for each has been adjusted to the same amount that you have previously estimated.
PRINCE2 Activities and resource levelling
The final part of activity planning checks for resource conflict. Perhaps the easiest way to visualise this, is to imagine two tasks which occur at the same time. If you place the resource, let’s call him Dave, full time on both tasks then Dave would be over-allocated as he cannot carry out both activities at the same time.
Sporting such over-allocations can be difficult if you’re carrying this out by hand, using a computer planning to all makes is far easier as they will usually have shown such over-allocated resources in red including identifying exactly where the resource is being overallocated so that you can resolve the problem.
To resolve the problem, you need to smooth or level the resources to get the required resources down below the level of available resources. Smoothing or levelling involves three basic steps:
- If an activity is not on the critical path, you can delay its start until a time when the person is available. You can then slide activities along with the person’s free time or float within the timeframe.
- If you still have a problem, see if you can get more resources if that helps. The project board may be able to give you more people with the same skill set as this list the level of available resources and so can easily resolve the problem.
- If you carry out the two steps above but still have a problem, then the project end date must have been moved to represent a realistic timeframe based on the available resources
