1. TermPaper – DIA baggage handling system
Hari Nagalla
12/01/2012
ESE6361

2. Denver International Airport - Background
One of the largest and most technologically advanced airports in the world
2X the size of Manhattan – 53 square miles
3 parallel north-south Runways, 2 parallel East-West runways. Room for 12 runways.
3 concourses and 88 gates.
Construction started in 1989, with scheduled open in 1993.

3. Automated Baggage Handling System
Designed to distribute all baggage including transfers, automatically between check-in, aircraft and baggage claim.
BAE contracted to design and install the system.
Project cost USD~190 M.
Most complex baggage handling system, other airports used similar design, but at a far reduced scale.

4. Motivations for advanced baggage handling system
Distances between ticket counters and gates/planes are much larger than most other airports.
To keep flights on schedule, speedy movement of baggage is critical (quick turn-around time – maximizes airline profitability)
Baggage transfer/movement is through under-ground tunnels, so telecarts are preferred.

5. Methods of Moving Bags Tug & Cart Telecars Labor intensive
Manual Method
Telecars
Multiple luggage pieces in one cart
Not automatically sorted
Typically used in automated systems

6. Methods of Moving Bags DCV – Destination Coded Vehicles
Each cart contains a single piece of luggage
Automatically sorted
Not typically used or well tested
Little or no human interaction required
Selected for the Automated Baggage System at DIA

7. Methods of moving bags DCV mechanics
Metal cart with wheels on the bottom and a plastic tub on top (mounted on a pivot) that tilts into three positions for automatically loading, carrying and unloading baggage
Ride on a metal track like a roller coaster
Travel up to 24 mph
Slow to 4.5 mph for loading and 8.5 mph for unloading
Photo-electric sensors trigger laser scanner when DCV is present and associate the bag with the DCV
Located every 150 to 200 feet of track
Data from scanners is transmitted to a computer that translates it by using a look up table to match the flight number with the appropriate gate

8. BAE Baggage system Functionality
Check-in
Bar code labels
Bag’s owner
Flight number
Final destination
Intermediate connections and airlines
Automated bar code scanner
Array of bar-code scanners arranged 360 degrees scan baggage
Typically able to scan 90% of luggage
Luggage unable to be scanned is routed to another conveyor to be manually scanned
Theoretically after reading the bar-code, the system will know where that bag is at all times

9. System components
class computers distributed in eight control rooms
Raima Corp. database running on a Netframe systems fault-tolerant NF250 server
High speed fiber-optic Ethernet network
14 million feet of wiring
56 laser arrays
400 frequency readers
10,000 motors
92 PLCs to control motors and track switches
3,100 standard baggage carts (DCVs)
450 over-sized baggage carts (DCVs)
2,700 photocells
Over 17 miles of track
Over 6 miles of conveyors

10. Baggage Handling Process
Conveyor belt feed the central network of DCVs.
Each bag is independently placed on the DCV, so delivery of bags from conveyor belts must be carefully controlled.
The conveyor belt can only advance when there is an empty cart onto which the leading bag on the conveyor belt can be placed.
The speed at which the conveyor belts can advance, and thus the performance of the entire system depends on the rate of delivery of empty carts to each conveyor belt.

12. Baggage Problems
Baggage handling system failed spectacularly, during test and demo runs. This resulted in postponing airport opening by several months.

13. Timeline : Mayor’s humiliation
March 2, 1993
Denver Mayor Wellington Webb announces the first airport opening delay. The October 31, 1993 opening date is changed to December 19, 1993 to allow for a seven week debugging of hundreds of systems.
October 25, 1993
Mayor Webb announces the second airport opening delay. The December 19, 1993 opening date is changed to March 9, 1994 to accommodate changes made by the airlines, allow more time to test critical airport systems, train airline ticket agents and other workers, and complete installation of fire and security systems.
March 1, 1994
Mayor Webb announces the third airport opening delay. The March 9, 1994 opening date is changed to May 15, 1994 to accommodate problems of troubleshooting the airport's complex baggage system. Mayor Webb further asserts that the airport will open on May 15th "come hell or high water."
May 2, 1994
Mayor Webb announces the fourth airport opening delay. The May 15, 1994 opening date is delayed indefinitely to resolve more problems encountered while testing the baggage system.

14. Timeline : Part II
June 20, 1994
The Webb administration announces that four steps are required in completion before a new opening date will be announced.
BAE must submit a master schedule.
Logplan and the city must evaluate the BAE master schedule and conduct several tests to see how realistic it is.
Denver must consult with the airlines on their recommendations.
The BAE's baggage system must operate for an unspecified period of time at an acceptable level.
August 4, 1994
Mayor Webb announces that the city will spend an extra $50 million to build a conventional airport-wide luggage system using traditional tugs and carts.
August 22, 1994
Webb announces that Denver International Airport will open on February 28, 1995.

15. Timeline : Part III September 7, 1994
Denver and BAE sign an agreement that allows BAE to work directly with United Airlines to simplify the baggage system so it can be ready for a February opening.
September 21, 1994
Denver and BAE begin mediation over who is to blame for the cost overruns and problems with the baggage system.
February 28, 1995
Concourse A's opening is postponed indefinitely, owing to litigation between Denver and Continental Airlines, which has cancelled its lease of 30 gates, and its operation of using Denver as a major hub. Concourse C, carrying 12 airlines, opens with a traditional tug and cart baggage system. Concourse B, housing all of United's gates, opens using the BAE automated baggage handling system only on outbound, Denver-originated flights.

16. What went wrong?
Despite its importance, the baggage handling system was an afterthought
The airport was 2 years into construction before the baggage system was considered
The system would have to be retrofit into the airport as it was designed initially including narrow tunnels and tunnels with sharp turns making it extremely difficult to navigate the DCVs

17. What went wrong? part II
The time constraint was impossible to overcome
The 21 month schedule precluded extensive physical testing or simulation of the full system design

18. What went wrong? Part III
Reliable Delivery
System consists of over a hundred waiting lines that feed into each other
Belt will only advance when there is an empty cart
Empty carts will only arrive after they have deposited their loads
Cascade of queues
Pattern of loads on the system are highly variable
Depend on the season, time of day, type of aircraft
The number of possible scenarios is enormous

19. What went wrong? Part IV Misreads
Compounded by the fact that not only are the scanners required to read data from the tags attached to the baggage, but the information must also be transmitted by radio to devices on each of the DCVs. This duality compounds the errors.

20. What went wrong? Part V Complexity
System of this size providing time sensitive delivery of materials on such a large scale had never been done before
12x as many carts traveling 10x the speed of carts typically used at that time
Not just an increase in complexity relative to current systems, but a leap in complexity
System must track tens of thousands of bags going to hundreds of destinations – all in real time
Distributed computer system
In addition to regular error checking, software must guard against electrical disturbances in the communications, have multiple levels of redundancy and be able to recover from errors very rapidly

21. What went wrong? Part VI Line-Balancing problem
All lines of flow should have balanced service
Need to have sufficient empty carts to accommodate the bags coming off the conveyor belt
In a postmortem simulation, the inability of the system to provide adequate empty carts was the primary cause of its failure. A simulation was also completed prior to the start of the project, but due to a lack of communication, BAE was not notified by airport officials of the results; The results stated, in essence, that the system would not work as it was initially designed

22. Lessons learnt - 1
Baggage handling is an integral part of Airport planning and construction. Due attention should be paid during Elaboration, design phase.
Making the system to work increases ‘exponentially’, as complexity increases. Automatic Baggage handling for entire airport is very complex with thousands of mechanical/control devices and SW systems.
Make smaller automatic systems (one for each concourse etc) to get confidence and then incrementally automate adding more consourses, terminals)

23. Recommendations - 1
Using RFID tags on bags (instead of barcode readers) may help improving mis-reads.
Line balancing/ allocation of empty carts to loading points may be optimized : - Use cameras at Ticket counters to monitor check-in pattern. Video analytics to identify bags. - Get checked-in bag info of the arriving flight in advance and allocate empty carts.

24. Recommendations - 2
There are similarities between Automated Baggage handling using DCVs and IP packet routing:
Bag – data packet
Baggage tag – packet header
Conveyor/DCV – Ethernet/ATM
Junction Switch – Router/Gateway
IP networks have evolved over time and lot of research, went into issues like – a) congestion control b) route selection, route balance. c) QoS (Quality of Service) – Some packets have precedence.
It may be worth studying these similarities to adapt some of the techniques from IP routing to automated baggage handling.

25. Acknowledgements
“The Baggage System at Denver: Prospects and Lessons,” Journal of Air Transportation Management, Vol. 1, No.4, Dec., pp , 1994.
“How Baggage Handling Works,” HowStuffWorks.com
The Baggage System at Denver: Prospects and Lessons – Dr. R. de Neufville – Journal of Air Transport
Management, Vol. 1, No. 4, Dec., pp , 1994“Simulating the Denver airport automated baggage System,” Dr. Dobbs Journal, January 1997