I’m trying out Project 2013 to use to run a test lab, so apologies for the noob question. This seems like a basic scenario but what I’ve found on this forum is “Project doesn’t work like that”:

I have a machine and an operator that are needed to complete a test. If I assign both the machine and the operator as a resource, Project seems to plan either-or depending on each resource’s availability. How do I “explain” to Project that both are needed at the same time to complete the task?

A simple example: Alice needs to drive the car to the grocery store, and Bob needs to drive to the laundromat. Both tasks have the car and the person assigned. Alice and the car get scheduled for the morning just fine. When I schedule the laundromat task, it assigns Bob to start first thing in the morning, and the car to start after Alice gets back from the store. How do I get Project to hold off scheduling Bob’s time until the car is back from the grocery store?

  • One thing I tried today that seemed to work was making a task for the machine and making a task for the person. I then linked the start and end dates on the two tasks. This seemed to schedule correctly, but the drawbacks I see are 1. I have to double the number of tasks in my project, and 2. I'm not sure if it will work at scale if the second task with the date links is the one with the resource constraint (i.e. will the links work in reverse). I will test this by assigning the car to the task with the links. Sep 22, 2020 at 16:52

2 Answers 2


(Assuming you are using the resource leveler,) un-check the box in leveling options for "Leveling can adjust individual assignments on a task." For finer control, you can leave the box checked (the default setting), then insert the "Level Assignments" column and set it to "No" for specific tasks where the work assignments must be concurrent.

  • This seems to work great in my "errands" demo project. Time to test it out on my lab schedule, and find some reading material on levelling.... Thank you! Curious as to the drawbacks of using this technique are. Sep 22, 2020 at 16:58

I will preface this that I am not sure it will work as you want in project but I would schedule a task dependency secondary to resources. In other words, I would schedule a FS relationship between the grocery task and the laundry mat task; therefore, both resources--car and Bob--won't be scheduled until after the grocery run is complete.

Edit to answer comment: First, @Tom Boyle's knowledge on MS Project seems quite deep so his answer is bankable in my opinion, but I did want to address your comment on dependencies. In projects, there essentially four types of dependencies: mandatory (like what you describe), discretionary (this is more what I am describing), internal, and external. Look up discretionary because this type of dependency is not uncommon and is used all the time. Shared resources fits this type perfectly.

Hope this helps!

  • Good suggestion, but I would like to maintain clear inter-dependencies in my projects. We have to injection mold pieces before we can test them, so having the testing task dependent on the molding task describes our activities accurately. I'd like to avoid making two tests inter-dependent on one another, because in reality they're not. It doesn't really matter to the laundromat that the grocery shopping is done, and vice-versa. Sep 22, 2020 at 16:47
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    @David Espina, thanks for the comment. Yes, discretionary logic ties are pretty common, and my first reaction to the grocery/laundry question was the same as yours. For a large, project of a certain complexity, however, those ties become pretty arbitrary-looking as the project progresses, and you become a slave to them. Resource leveling offers a neat option, but it's not trusted by many (for valid reasons.)
    – Tom Boyle
    Sep 23, 2020 at 1:25

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