## Resources Histograms (RHs)

Below, you can see an organised Cascade Diagram. The numbers in brackets represent the number of workers required to complete each activity.

*Possible criteria:*- Minimum time
- Minimise total cost (this may change minimum total time)
- Make maximum use of resources (e.g. schedule for a fixed number of people)

**Example:**Below, you can see an organised Cascade Diagram. The numbers in brackets represent the number of workers required to complete each activity.

Ignoring the numbers in brackets - if it was only one worker per activity, we can see you would need 3 workers to complete the project in 17 time units.

The RH for the case where there is only one worker per activity looks like this:

The RH for the case where there is only one worker per activity looks like this:

As you can see, a resources histogram displays how many of our resources, y, are being employed at a particular time, x. From the Cascade Diagram we can see that all three workers are working until the time of 8, where one stops. This means that only workers 1 and 3 (2 resources) are working until time unit 13, where worker 3 stops and worker 2 starts – but we still have 2 resources employed (they just switch). At time unit 16, worker 2 stops again, while worker 1 continues (1 resource) until time unit 17.

Now, using the information given in brackets showing how many workers are required per activity, our resources histogram looks a lot different. In order to complete the project in the same amount of time, our resources histogram would look like this:

Now, using the information given in brackets showing how many workers are required per activity, our resources histogram looks a lot different. In order to complete the project in the same amount of time, our resources histogram would look like this:

You can see that we now need 7 people to complete the project in the given time. To form this RH, we use the Cascade Diagram above – look at each interval and see how many resources need to be employed within that time frame. E.g. in the 0-1 interval, we are carrying out A (2 resources), B (1 resource) and C (1 resource) at the same time – so we need 4 resources to be employed (2+1+1). Continue like this for each interval to form the RH.