You can use the General resource and Product/Service object types to have the current capacity of a resource determine which path of a control flow is passed.
Procedure
Place an object of the General resource or Product/Service type between two events that branched off via an OR or XOR rule.
Name the object and draw a connection to each of the events.
Enter attribute values for Maximum capacity, Minimum capacity, and Startup capacity (Simulation attribute type group).
Enter the comparison value in the Comparison value (numeric) attribute of each event and specify the comparison operator.
The model paths are passed according to your input during the simulation run.
Example