Waiting/Storage Cost

Modeling How-To's > Cost Modeling > Waiting/Storage Cost

Increment the unit cost of an entity based on the time spent waiting in a storage or buffer.

The model used for this example, as well as all of the modeling "how-to" examples, can be found in the ProModel Solutions Café (http://www.promodel.com/solutionscafe/howto/).

In the Variables and Attributes window, define an entity attribute to record the start of the waiting time (e.g., Wait_Start).
In the Logic for the storage or buffer, assign the clock time to Wait_Start (e.g., Wait_Start = Clock(min)).
In the routing dialog for the storage or buffer increment the entity cost by the time spent waiting times the cost per hour (e.g., IncCost (Entity, (Clock(min) – Wait_Start) * <rate>)).

A doctors office wants to assign a $20 per hour penalty cost to his operation for Patient waiting time in the Waiting Room.

Wait Room logic is shown below.

Routing logic is shown below.

Notice the logic defined to record the waiting start time and the hourly rate times the lapsed waiting time.