Each year I work with new bright-eyed future experts in planning and scheduling as they make the transition from their academic studies to the murky world of applied planning and scheduling. One of the first rules of thumb I suggest is to ensure everyone has the same view of the problem. Is this a planning problem or a scheduling problem or both? If both are being done simultaneously, the following example quickly illustrates the value in separating them.
As an example assume we have two conference rooms, 4MB1 and 4MB2, and schedule requests are handled as 1-hour slots for these two conference rooms. The collective resource for these two conference rooms is referred to as 4MB. We have two options to plan and schedule:
Let’s first look at simultaneous planning and scheduling. The first request is:
- Mariana for one hour starting at 9:00 AM
We make the following assignment:
This is followed by:
- Sophia for 2 hours starting at 10:00 AM
The last request is:
- Harpal for 3 hours starting at 9:00 AM
The final solution when we simultaneously plan and schedule is as follows:
Where the three requests were:
- Mariana for one hour starting at 9:00 AM
- Sophia for 2 hours starting at 10:00 AM
- Harpal for 3 hours starting at 9:00 AM
It is clear that this solution meets all three requests and is capacity feasible. However, no one would view this as the best solution. To get to the best solution requires rescheduling.
If separate planning and scheduling, the approach would be as follows:
Step 1: Aggregate the two rooms and create an aggregated capacity available.
Step 2: Record the three requests by person and time slot and summarize resource required.
Step 3: Compare capacity required to capacity available to insure a feasible solution is available.
Step 4: Turn the plan into a schedule, which generates the following schedule.
This schedule is an improvement in the previous schedule since Harpal does not need to change rooms.
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