Presentation is loading. Please wait.

Presentation is loading. Please wait.

Management of Waiting Lines

Similar presentations


Presentation on theme: "Management of Waiting Lines"— Presentation transcript:

1 Management of Waiting Lines
Chapter 18 Management of Waiting Lines McGraw-Hill/Irwin Copyright © 2012 by The McGraw-Hill Companies, Inc. All rights reserved.

2 Chapter 18: Learning Objectives
You should be able to: What imbalance does the existence of a waiting line reveal? What causes waiting lines to form, and why is it impossible to eliminate them completely? What metrics are used to help managers analyze waiting lines? What are some psychological approaches to managing lines, and why might a manager want to use them? What very important lesson does the constant service time model provide for managers? 18-2 Student Slides

3 Queuing Theory Queuing theory
Mathematical approach to the analysis of waiting lines Applicable to many environments Call centers Banks Post offices Restaurants Theme parks Telecommunications systems Traffic management 18-3 Student Slides

4 Why Is There Waiting? Waiting lines tend to form even when a system is not fully loaded Variability Arrival and service rates are variable Services cannot be completed ahead of time and stored for later use 18-4 Student Slides

5 Waiting Lines: Managerial Implications
Why waiting lines cause concern: The cost to provide waiting space A possible loss of business when customers leave the line before being served or refuse to wait at all A possible loss of goodwill A possible reduction in customer satisfaction Resulting congestion may disrupt other business operations and/or customers 18-5 Student Slides

6 Waiting Line Characteristics
The basic characteristics of waiting lines Population source Number of servers (channels) Arrival and service patterns Queue discipline 18-6 Student Slides

7 Simple Queuing System Calling population Arrivals Waiting line Exit
Service System Processing Order 18-7 Student Slides

8 Population Source Infinite source Finite source
Customer arrivals are unrestricted The number of potential customers greatly exceeds system capacity Finite source The number of potential customers is limited 18-8 Student Slides

9 Channels and Phases Channel Phases A server in a service system
It is assumed that each channel can handle one customer at a time Phases The number of steps in a queuing system 18-9 Student Slides

10 Arrival and Service Patterns
Arrival pattern Most commonly used models assume the arrival rate can be described by the Poisson distribution Arrivals per unit of time Equivalently, interarrival times are assumed to follow the negative exponential distribution The time between arrivals Service pattern Service times are frequently assumed to follow a negative exponential distribution 18-10 Student Slides

11 Waiting Line Metrics Managers typically consider five measures when evaluating waiting line performance: The average number of customers waiting (in line or in the system) The average time customers wait (in line or in the system) System utilization The implied cost of a given level of capacity and its related waiting line The probability that an arrival will have to wait for service 18-11 Student Slides

12 Queuing Models: Infinite Source
Four basic infinite source models All assume a Poisson arrival rate Single server, exponential service time Single server, constant service time Multiple servers, exponential service time Multiple priority service, exponential service time 18-12 Student Slides

13 Common Queuing Systems
Student Slides

14 Finite-Source Model Appropriate for cases in which the calling population is limited to a relatively small number of potential calls Arrival rates are required to be Poisson Unlike the infinite-source models, the arrival rate is affected by the length of the waiting line The arrival rate of customers decreases as the length of the line increases because there is a decreasing proportion of the population left to generate calls for service Service rates are required to be exponential 18-14 Student Slides

15 Psychology of Waiting If those waiting in line have nothing else to occupy their thoughts, they often tend to focus on the fact they are waiting in line They will usually perceive the waiting time to be longer than the actual waiting time Steps can be taken to make waiting more acceptable to customers Occupy them while they wait In-flight snack Have them fill out forms while they wait Make the waiting environment more comfortable Provide customers information concerning their wait 18-15 Student Slides

16 Operations Strategy Managers must carefully weigh the costs and benefits of service system capacity alternatives Options for reducing wait times: Work to increase processing rates, instead of increasing the number of servers Use new processing equipment and/or methods Reduce processing time variability through standardization Shift demand 18-16 Student Slides


Download ppt "Management of Waiting Lines"

Similar presentations


Ads by Google