In SYNCHRO 4D Pro, task durations can be automatically calculated based on two options 1. Physical Quantity Dependent and 2. Resource Unit Dependent. In this article, the focus will be more on option 2.

To know more about physical quantity dependent please refer to this video SYNCHRO 4D: Physical Quantity Dependent Tasks and Durations

First Thing First

  1. For the selected task, go to Task Properties>General>Duration Type> Set it to Resource Units Dependent
  2. Go to the assigned resource that is going to drive the duration Task Properties>Resources>select the driving Resource and tick on “Driving” and “Fixed Units.

How does it work?

There are 4 interdependent SYNCHRO parameters i. Duration, ii. Planned Units iii. Planned unit/time iv. Planned Resource Count

In this example, let’s consider to finish a task 80 human-hours (also known as man-hours or machine-hours) are required. A single worker works 8 human-hours per day.

The Planned Units of the resource under consideration will be = 80 human-hours
Planned units/time = 8 human-hours/day (This by default comes from the SYNCHRO Calander Working Day hours)

Duration = Planned units/ Planned Units/time
= 80/8
= 10 days
Planned Resource Count = Planned Units/Duration (in hours)
= 80/(10*8)
= 1

Now let’s consider 2 workers working simultaneously per day.
Then the Planned units/ time will be twice i.e 2×8 = 16 human-hours/ day
Thus new duration required will be 5 days.
Note the Planned Resource Count will also change to 2 as now workers are working together.

Calculating the number of resources required or Planned Resource Counts

The other way round can also be calculated i.e number of resources required for a certain duration. The Planned units i.e. the total human-hours required will remain constant.

Let’s consider the task needs to be completed in 2 days. Here, SYNCHRO will automatically calculate the Planned Resource Count and Planned Units/ time

Planned Units/time = 80/2
= 40 human-hours/day
Resource Counts = 80/(2*8)
= 5

If the “Fixed” option was not marked, changing the Duration will automatically update the Planned Units without affecting the Planned Units/time and Planned Resource Count. More information regarding these interdependent parameters can be learned from the SYNCHRO Help page named “Resource Units Dependent“.

Play around with the attached example file to learn more about this. In the future, a best practice workflow will be discussed on how required man-hours can be calculated from the physical quantity of assigned resources of the task.


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