Working With Loading Patterns

One of the key elements that needs to be considered when assigning resources is the question of exactly *when* the resource will perform the work. Will they do it as early as possible, as late as possible or spread it out over the duration of the task?

The Loading Pattern provides the answer to this question. Incidentally, it is also the element most-often overlooked by Project Managers, and is a source of some considerable frustration for a few! You can use the Loading Pattern in conjunction with Autoschedule to produce a workable schedule that allows for real-world variations in the way work is performed.

There are five Loading Patterns in Open Workbench (unlike MS Project, which has – I think – about a dozen or more, the Loading Patterns in Open Workbench mean what they say, and they actually work):

  • Front
  • Back
  • Contour
  • Uniform
  • Fixed

Front Loading

The Front loading pattern assigns work effort as early in the task as possible. Resources are assigned to get work done as early as their Availability permits. The diagram below depicts a Task (“Front Loading”) that has 2 resources assigned to it (one at 100% Max % and the other at 50%), each with 60 hours of Work Effort to perform:

The resource that is 100% available completes his 60 hours of work in the first 7.5 day of the task duration, whereas the resource that is 50% available takes 15 days to complete his 60 hours.

Back Loading

The Back loading pattern assigns work effort as late in the task as possible. Resources are assigned to get work done as close to the finish as their Availability permits. The diagram below depicts a Task (“Back Loading”) that has our 2 friends – Max % 100 and Max % 50 assigned to it:

Again, the task duration is determined by Max % 50, who can only spend half his time on this task. His work effort is spread over 3 weeks, but Max % 100 completes his work in the final 7.5 days of the task duration.

Contour Loading

The Contour loading pattern is perhaps the most flexible. It fits the work to be completed around the other work assigned to the resource, and attempts to smooth out the effort as much as possible.

Changes made to the duration of the task after it has been scheduled cause resource assignments to behave like the Uniform pattern (see below). The diagram below depicts a task (“Contour Loading”) with Max % 100 and Max % 50 assigned to it:

With the Contour loading pattern, the work to be performed is “smoothed out” over the task duration.

Uniform Loading

The Uniform loading pattern will require a resource to work on a task only on those days when the resource has sufficient Availability to meet the task requirements. If a resource is scheduled to work 4 hours per day on a task, but for some reason there is a day when the resource is only available to work on the task for 3 hours, he will not be scheduled to work on that task on that day. As with the Contour loading pattern, the Uniform loading pattern endeavours to “smooth out” the work over the task duration, as depicted here:

Fixed Loading

The Fixed loading pattern enables the user to manually schedule work. Open Workbench will automatically *lock* fixed-loaded resource assignments so they are not changed when the Autoschedule or Recalculate functions are run.

You can use the Fixed loading pattern to create “split” tasks, which start, then stop, and then start up again. The diagram below shows a task with a Fixed loading pattern:

The easiest way to become familiar with Loading Patterns is to use them. When Open Workbench is installed, it sets the default Loading Pattern as “Front”, but you can change this using the Open Workbench -> Preferences feature (or Tools –> Options in OWB 1.1.6) to bring up the Options dialog box. Select the Defaults tab and change the Loading Pattern.

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2 Responses to Working With Loading Patterns

  1. Pingback: Managing Resource Assignments | Open Workbench Warrior

  2. Stephane says:


    First, thanks for bringing back a forum on OW ! hope this one will live and grow šŸ™‚

    Beeing a 10 years OW user, I’d like to add two points to your article :
    – I would personnaly strongly advise NOT to use uniform Loading Pattern, since it has a strange behavior : it seems to schedule work effort only in a continuous way. In your example, to schedule a 4 days effort, OW will seek 4 continuous days where the resource has the needed capacity. If, for example, the same resource is already scheduled 2 days per week on a task, for a 6 month duration, the uniform task will start at the end of this 6 month task. So this LP is to use with caution.
    – Using Contour and Front loading is strictly identical, as long as you don’t have any network constraints in your planning (fixed duration or locked task).

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