Staging queues in material handling and transportation systems

In most physical queueing applications, customers join a queue and move forward after each service, leaving room for others to join behind them. Some queues found in material handling and transportation systems do not operate like this because the queued entities (pallets or unoccupied cars, for example) are incapable of moving forward autonomously. We develop a model for the resulting staging queue, and give simulation results for several configurations