1. Waiting Line Management
Ross L. Fink

2. Example of Waiting Lines
All organizations, both manufacturing and service, have some type of waiting line

3. Why Do Lines Form?
Limited resources--short term
Cultural

4. Waiting Line Costs
Cost of service
Cost of waiting

5. Characteristics of Waiting Lines
Population Source
Finite
Infinite
Arrivals
Pattern
Controllable
Uncontrollable

6. Characteristics of Waiting Lines
Size of arrivals
single
batch
Distribution of arrival rate
Poisson
Erlang
Degree of patience
Patient
Impatient

7. Characteristics of Waiting Lines
Length
Infinite
Limited capacity
Number
Single
Multiple

8. Characteristics of Waiting Lines
Queue discipline
First come, first served
Reservations first
Emergency needs
Others

9. Characteristics of Waiting Lines
Service facility
Distribution of service time
Constant
Exponential
Erlang
Channels
Phases

10. Solution Methods
Queuing Theory
Simulation

11. Implications of Service Rate v. Arrival Rate
Queuing models are only derived for the situation where service rate is greater than arrival rate (see formulas)
If arrival rate greater than service rate--lines approach infinite length over time

12. Hints for Using Queuing Formulas
Make sure
that  is service rate (units per time, e.g., customers per hour)
that  is arrival rate
that  is greater than 
 and  are in the same time units
Understand that system is composed of line and service