I am attempting to plan a project in microsoft project 2013 which uses a piece of large machinery with substancial fuel costs. My sponsor wishes to incorperate fuel as a resource.

Attempting to set it as a material resource and applying to the task at a rate of "100/h" in the units column on the resource form calculates it correctly initially. As the duration changes, however, the calculated work does not change as the 100/h is only a one time calculation.

How can I have a variable material cost for a task based on the tasks duration or for the work performed by another resource?


Create a macro or custom field (complicated for other users)

Set fuel as a work resource rather than a material resource (counter intuitive)

  • 1
    How would your track a variable-rate resource like this without MS Project? --Sometimes the tool just gets in the way.
    – Todd A. Jacobs
    Apr 16 '14 at 15:56
  • Track hours for the equipment and convert. Unfortunately my bosses want it in the plan.
    – tem
    Apr 16 '14 at 16:01
  • 1
    "My sponsor wishes to incorperate fuel as a resource." Why? This smells like an X/Y problem; what problem does he intend to solve with this specific solution? Run costs including fuel should be calculable (or at least estimatable within a range), but there must be some business reason driving the desire to track fuel use separately.
    – Todd A. Jacobs
    Apr 17 '14 at 16:32
  • Because it is ordered on site and we need to know how much needs to be ordered in addition to normal requirements in order to support the project. It would be convient to be able to adjust the cost/gallon of the resource and have it adjust project costs immediately rather than updating everything reliant on that number. Because it makes intuitive sense. Because equipment scheduled for repairs doesn't use fuel while equipment scheduled for operation doesn't (could be done via different costs I know). I can't come up with a reason not to do this if it is a significant portion of our costs.
    – tem
    Apr 17 '14 at 17:35
  • I don't think there's a reason not to track important costs; I just think trying to track a variable cost within a given tool might be problematic. Have you considered making each run or fuel purchase a unique resource, so that your cost basis can be estimated and adjusted without having to change the estimated or calculated value throughout the plan?
    – Todd A. Jacobs
    Apr 17 '14 at 17:39

When you purchase the fuel, it is spent. If the machine takes 100 gallons and you need it April 12, you load the 100 gallons on April 12 in your schedule at your estimated cost. There is no value tracking the fuel burn because there is nothing you can do with the performance variance. Once the fuel is loaded, it is gone. (I retract this entire answer, above; I was too narrowly focused.)

EDIT: My original answer was constrained by thinking only from like an earned value perspective, but after thinking about this more, and the comment below from the OP regarding his attempt at planning, I think I was looking at this through a paper towel holder.

For estimation, I would use the data I have already collected around work and duration for labor as an input into my fuel estimation. The manufacturer of the machine ought to have a rated fuel burn for its use, like a car's miles per gallon or a plane's gallons per hour. That datum is also an input to your estimation. If you have historical fuel burn values, then that is also an input.

So as an example: If in my work package I estimated 100, 180, 125 hours (optimistic, pessimistic, most likely) of work; and 10, 25, 13 days duration. For planning values, based on my risk analysis, I may choose 135 hours of work and 15 days of duration to load into my schedule.

In this particular package, the machine is expected to operate about 80% of the time. So only using this is a guiding principle, 80% of 135 hours might be the planning value I use for fuel usage, or 108 hours. I can reduce or add to that based on other risk factors.

Continuing this example, the machine might be rated at 35 gallons per hour and my historical data might show I typically get 30 to maybe as high as 38 gallons per hour. So for a planning value I might choose 33 gallons per hour to load some buffer. 33 x 108 is 3,564 gallons to be used in that package over the 15 days of work.

Price of fuel is also variable. I would apply the same logic to the price per gallon and choose the value that is best suited for risk purposes.

Loading the fuel into the schedule depends on how you are purchasing it. Are you purchasing all the fuel at once and storing it or as you go? If as you go, I would load a separate control account for materials and underneath this a package for fuel. I would schedule the fuel purchase when I would expect to purchase it, the quantity and the associated cost based on my estimation above. If you run out early or have more than expected at the next purchase, you would load the actuals just like labor and track your variances, which would then allow you to readjust your planning values if and when you replan your work down the line.

I hope this helps and good luck!

  • Not true at all for this situation; fuel is purchased and stored on site. If it isn't used for task A it is available for task B or regular production rather than the project. (The equipment is used regularly and is owned by the company but scheduling its use is of high priority.)
    – tem
    Apr 17 '14 at 12:18
  • If you mean you can't take the fuel out of the vehicle, more fuel would not be needed to be added. These tasks often span several fuel refills.
    – tem
    Apr 17 '14 at 13:32
  • @tem I think David's point is that it's a front-loaded cost for each fill, and that trying to amortize the cost over multiple work packages may not be useful as a project control.
    – Todd A. Jacobs
    Apr 17 '14 at 14:01
  • Unless I am missunderstanding your terms (99.9% sure i understand), I understood what he said correctly and my second comment addressed that. There are several fills within a single work package. If the task takes 10% longer it results in 10% more fuel usage (as long as it actually running longer and not downtime). However you would run it, I have to run it by my bosses' perceived best practices and front loading the cost is not sufficient. As a policy, this does not address my stationary equipment that does not have a fuel tank.
    – tem
    Apr 17 '14 at 14:09
  • I think my answer is still correct. If you inventory, you still allocate the cost once when it goes into the machine, so tracking fuel burn, like performance, seems wasteful. Apr 17 '14 at 15:21

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