Queuing theory is the study of waiting lines. It is one of the oldest and most widely used quantitative analysis techniques. Waiting lines are an everyday occurrence, affecting people shopping for groceries, buying petrol, making a bank deposit or waiting to buy movie tickets.
The theory is applicable to situations where the customers arrive at some service station for some service; wait (occasionally not) and then leave the system after getting the service. In such ‘arrival and departure’ problems, the customers might be people waiting to deposit their electricity bills at a cash counter, machines waiting to be repaired in a factory’s repair shop, patients in a hospital who need treatment and so on…The service stations in such problems are the cash counters in the electricity office, repairman in shop and doctors attending the patients respectively.
The waiting lines develop because the service to a customer may not be rendered immediately as the customer reaches the service facility. Thus lack of adequate service facility would cause waiting lines of customers to be formed. The only way that the service demand can be met with ease is to increase the service capacity to a higher level. But that will mean higher cost of servicing. A manager therefore, has to decide on an appropriate level of service which is neither too low nor too high.
Basic Characteristics:
1) Queue Length
2) System Length
3) Waiting time in the queue
4) Total time in the system
Various types of Queuing System
1) A Single Service facility
2) Multiple Parallel Facilities with Single Queue
3) Multiple Parallel Facilities with Multiple Queue
4) Service Facilities in a Series
