CHAPTER 18 Waiting Lines

Waiting lines are non-value added occurrences Disney World Waiting in lines does not add enjoyment Waiting in lines does not generate revenue Waiting lines are non-value added occurrences

Waiting Lines Queuing theory: Mathematical approach to the analysis of waiting lines. Goal of queuing analysis is to minimize the sum of two costs Customer waiting costs Service capacity costs Waiting lines are non-value added occurrences

Implications of Waiting Lines Cost to provide waiting space Loss of business Customers leaving Customers refusing to wait Loss of goodwill Reduction in customer satisfaction Congestion may disrupt other business operations

Queuing Analysis Figure 18.1 Cost Service capacity Optimum Total cost Customer waiting cost Capacity cost = + Total cost Cost Cost of service capacity Cost of customers waiting Service capacity Optimum

System Characteristics Population Source Infinite source: customer arrivals are unrestricted Finite source: number of potential customers is limited Number of observers (channels) Arrival and service patterns Queue discipline (order of service)

Elements of Queuing System Figure 18.2 Arrivals Service Waiting line Exit Processing order System

Queuing Systems Multiple channel Multiple phase Figure 18.3 Channel: A server in a service system

Poisson Distribution Figure 18.4

Waiting line Models Patient Reneging Jockeying Balking Customers enter the waiting line and remain until served Reneging Waiting customers grow impatient and leave the line Jockeying Customers may switch to another line Balking Upon arriving, decide the line is too long and decide not to enter the line

Waiting Time vs. Utilization Figure 18.6 System Utilization Average number on time waiting in line 100%

System Performance Measured by: Average number of customers waiting Average time customers wait System utilization Implied cost Probability that an arrival will have to wait

Queuing Models: Infinite-Source Single channel, exponential service time Single channel, constant service time Multiple channel, exponential service time Multiple priority service, exponential service time

Priority Model Arrivals Service Waiting line Exit Processing order System 1 2 3 Arrivals are assigned a priority as they arrive

Finite-Source Formulas Table 18.6 Average number being served Service factor Average number waiting Average waiting time Average number running Number in population

Finite-Source Queuing Not waiting or being served Waiting Being served J L H U W T

Other Approaches Reduce perceived waiting time Magazines in waiting rooms Radio/television In-flight movies Filling out forms Derive benefits from waiting Place impulse items near checkout Advertise other goods/services

Managing Queues by Business Rules Queuing QAP9 Managing Queues by Business Rules

Waiting Line Management DWL5 Disney Fast Pass Results/Distributing Queues

Fast Pass at Disney’s Animal Kingdom—Statistics Pilot Queue System DWL6 Fast Pass at Disney’s Animal Kingdom—Statistics

Other Queue Perception Improvers DWL7 Disney World—Traditional Queue Improvement Methods