Waiting line


Published on

  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Waiting line

  2. 2. WHERE THE TIME GOES In a life time, the average person will spend:SIX MONTHS Waiting at stoplights EIGHT MONTHS Opening junk mail ONE YEAR Looking for misplaced 0bjects TWO YEARS Reading E-mailFOUR YEARS Doing housework FIVE YEARS Waiting in line SIX YEARS Eating 12-4
  3. 3. TEN PROPOSITIONS ON THE PSYCHOLOGY OF WAITING LINES1. Unoccupied time feels longer2. Preprocess/post-process waiting feels longer than in-process3. Anxiety makes waiting seem longer4. Uncertain waiting is longer than known, finite waiting5. Unexplained waiting seems longer6. Unfair waiting is longer than equitable waiting7. People will wait longer for more valuable services8. Waiting alone feels longer than in groups9. Physically uncomfortable waiting feels longer10. Waiting seems longer to new or occasional users Sources: Maister; Davis & Heineke; Jones & Peppiatt
  4. 4. COMPONENTS OF THE QUEUING SYSTEM Servicing System Servers Queue orCustomer Waiting LineArrivals Exit
  5. 5. LAWS OF SERVICE Maister’s First Law: Customers compare expectations with perceptions. Maister’s Second Law: Is hard to play catch-up ball. Skinner’s Law: The other line always moves faster. Jenkin’s Corollary: However, when you switch to another other line, the line you left moves faster. 12-7
  6. 6. CUSTOMER SERVICE POPULATION SOURCES Population Source Finite InfiniteExample: Number of Example: Themachines needing number of peoplerepair when a who could wait incompany only hasthree machines. a line for gasoline.
  7. 7. SERVICE PATTERN Service Pattern Constant VariableExample: Items Example: Peoplecoming down an spending timeautomated assembly shopping.line.
  8. 8. THE QUEUING SYSTEM LengthQueue Discipline Queuing Number of Lines & Line Structures System Service Time Distribution
  9. 9. EXAMPLES OF LINE STRUCTURES Single Multiphase Phase One-personSingle Channel Car wash barber shop Bank tellers’ HospitalMultichannel windows admissions
  10. 10. ESSENTIAL FEATURES OF QUEUING SYSTEMS Renege Arrival Queue process DepartureCalling Queue discipline Servicepopulation configuration process Balk No future need for service 12-12
  11. 11. ARRIVAL PROCESS Arrival process Static Dynamic Random Random arrival Customer- Facility- exercised arrivals with rate varying controlled controlconstant rate with timeAccept/Reject Price Appointments Reneging Balking 12-13
  12. 12. QUEUE DISCIPLINE Queue discipline Static Dynamic (FCFS rule) selection Selection based based on status on individual of queue customer attributesNumber of Processing timecustomers Round robin Priority Preemptive of customers waiting (SPT or cµ rule) 12-14
  13. 13. WAITING LINE SYSTEMIncludes the customer population source as wellas the process or service system.QUEUING SYSTEMAnother name to define a waiting line.FINITE CUSTOMER POPULATIONThe number of potential new customers isaffected by the number of customers alreadyin the system.
  15. 15. INFINITE CUSTOMER POPULATIONThe number of potential new customers is notaffected by the number of customers already inthe system.BALKINGThe customer decides not to enter the waitingline.RENEGINGThe customer enters the line but decides toexit before being served.
  16. 16. JOCKEYINGThe customer enters one line and then switchesto a different line in an effort to reduce thewaiting time. THE NUMBER OF WAITING LINES THE NUMBER OF SERVERS THE ARRANGEMENT OF THE SERVERS
  17. 17. ARRIVAL AND SERVICE PATTERNS Arrival rate The average number of customers arriving per time period. Service rate The average number of customers that can be served per time period.Waiting Line Priority Rules Generally customers considerfirst-come, first-served to be the fairest method for determiningpriority. Other rules include best Customers first, highest profitcustomer first, quickest service requirement first, largest servicerequirement first, emergencies first...
  18. 18. CRITERIA FOR SEGMENTATION ANDALLOCATION OF QUEUING POPULATION Urgency of job  emergencies vs. non-emergencies Duration of service transaction  number of items to transact  complexity of task Payment of premium price  First class vs. economy Importance of customer  frequent users/loyal customers vs. others
  19. 19. WAITING LINE PERFORMANCE MEASURES 1.The average number of customers waiting in line and in the system. 2. The average time customers spend waiting, and the average time a customer spends in the system. 3. The system utilization rate.
  20. 20. BENEFITS OF A RESERVATIONS SYSTEM Controls and smoothes demand Pre-sells service Informs and educates customers in advance of arrival Customers avoid waiting in line for service (if service times are honored) Data capture helps organizations prepare financial projections
  21. 21. CHARACTERISTICS OF WELL- DESIGNED RESERVATIONS SYSTEMS Fast and easy for customers and staff Can answer customers’ questions Offers options for self service (e.g. Web) Accommodates preferences (e.g., room with view) Deflects demand from unavailable first choices to alternative times and locations Includes strategies for no-shows and overbooking  required deposits discourage no-shows  unpaid bookings canceled after designated time  compensation for victims of over-booking
  22. 22. CHANGING OPERATIONAL CHARACTERISTICS Customer arrival rates. Number and type of service facilities. Changing the number of phases. Server efficiency. Changing the priority rule. Changing the number of lines.