Activity Day Counts

You might call me sad but I love a good activity day count. Simple to put together and a great visual representation of the project workload.

So first of all, an activity day count (ADC) is measure of the total and rate of works to be completed. It is a count of the number of days for each activity plotted cumulatively against time.

So this is what one looks like.

On its own its a pretty pointless, the information needs to be understood. They really become useful when comparing ADCs from different programme revisions.

Here's how to read and understand the information:


This shows the intensity of the work to be completed. A steeper line indicates a higher rate of work than a shallow line.

Previous programme line

When comparing against a previous programme ADCs become even more useful. Anything below the line is behind, anything above is ahead. An increase may be due to additional scope but because all work is effectively on a level playing field (ie there is no weighting for critical of harder activities) it shows that you have completed more or less work than planned in the period.

Date Date

This is the date of the programme used to create the ADC S-Curve. Anything to the left of the line is an asbuilt and anything to the right is a forecast.

This can be quite useful when comparing programmes, it will pick up if someone has tampered with an asbuilt activity. The graph will show a change in the graph before the earliest data date which in theory shouldn't happen.

Flat Spots

These show periods of inactivity where no work is completed. Normally found during holiday periods but can also show seasonal working or breaks in continuity.

Curve Length

As time is plotted on the X-Axis the length of the curve is the duration. An increase in the length of an ADC curve signifies prolongation of the works.

Curve Height

Cumulative activity days are plotted on the Y-Axis so height of the curve shows the total amount of work to be undertaken. Higher = more work. Lower = less work.

This could be an increase in scope or the same scope with decreased outputs.

As an ADC doesn't weight an activity (i.e. all earn the same count regardless of complexity) the total often increases when breaking activities down into more detail. To accurately compare an ADC a breakdown of detail is fine if the same count is achieved. For example a 20day activity is broken down into 4 5day activities. This wouldn't change the total ADC however if the 20day activity was broken into 8 5day activities to show a breakdown in detail and discipline then the ADC for this activity would double and show as an increase in total ADC.

Now there are some pros and cons to using ADCs which I will summarise. This isn't a complete list, you might find your own but these are the most common in my experience.


🔸 Easy visualisation of the change between programmes

🔸 Counts critical and non critical the same so focus on critical only activities will show under-performance against the plan.

🔸 Useful in demonstrating thickening of prelims

🔸 Easy identification of flat spots in works for possible levelling


🔸 Can be manipulated by miscounting (i.e. allocating more or less than one per activity day) - Yes people do this to manipulate the graph!

🔸 Breakdown of detail can sometimes be misleading so further investigation can be required

🔸 Critical path awarded the same weighting as non critical - Its possible to do an ADC on critical only by filtering but I'd use this to support the main ADC. As in the Pros, its good to have overall visibility of all activities and not just focus on the critical.

Activity day counts are a great way of demonstrating change to a regular programme update. I particularly like that they pick up all activities, they really flag up when only critical activities are being undertaken.

I've used Activity Day Counts to help demonstrate prelim thickening, show programme change through time on a contract with vast amounts of change and as a visual for monthly programme updates.

Great tool, when used properly they become very useful but with anything. Rubbish in = Rubbish out!

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