Queuing System Or Process

Service Mechanism or Service Facility (cont.):

(a)   Service facility design:

 Arriving customers may be asked to form a single line (Single queue) or multi-line (multi queue) depending on the service need. When they stand in single line it is known as Single channel facility when they stand in multi lines it is known as multi-channel facility.

 Single channel queues:

•       If the organization has provided single facility to serve the customers, only one unit can be served at a time, hence arriving customers form a queue near the facility.
•       The next element is drawn into service only when the service of the previous customer is over.
•          Here also depending on the type of service the system is divided into Single phase and Multi-phase service facility.
•          In Single channel Single Phase queue, the customer enters the service zone and the facility will provide the service needed. Once the service is over the customer leaves the system.
•        For example, Petrol bunks, the vehicle enters the petrol station. If there is only one petrol pump is there, it joins the queue near the pump and when the term comes, get the fuel filled and soon after leaves the queue.
•          When the input rates increases, and the demand for the service increases, the management will provide additional service facilities to reduce the rush of customers or waiting time of customers.
•          In such cases, different queues will be formed in front of different service facilities.
•          If the service is provided to customers at one particular service center, then it is known as Service Mechanism or Service Facility

(b)   Queue discipline or Service discipline:

When the customers are standing in a queue, they are called to serve depending on the nature of the customer. The order in which they are called is known as Service discipline. There are various ways in which the customer called to serve. They are:

 First In First Out (FIFO) or First Come First Served (FCFS)

Last in first out (LIFO) or Last Come First Served (LCFS)

Service In Random Order (SIRO)

Service By Priority

•         We are quite aware that when we are in a queue, we wish that the element which comes should be served first, so that every element has a fair chance of getting service.
•         it is understood that it gives a good morale and discipline in the queue. When the condition of FIFO is violated, there arises the trouble and the management is answerable for the situation.
•          In this system, the element arrived last will have a chance of getting service first.
•          In general, this does not happen in a system where human beings are involved. But this is quite common in Inventory system.
•         In this case the items are called for service in a random order.
•         The element might have come first or last does not bother; the servicing facility calls the element in random order without considering the order of arrival.
•         This may happen in some religious organizations but generally it does not followed in an industrial / business system.
• Priority disciplines are those where any arrival is chosen for service ahead of some other customers already in queue.
• In the case of Pre-emptive priority the preference to any arriving unit is so high that the unit is already in service is removed / displaced to take it into service.
•       A non- pre-emptive rule of priority is one where an arrival with low priority is given preference for service than a high priority item.