Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering
Transport Technology

E.J. Oosterhuis Bagageafhandeling op luchthavens
Literature survey, Report 2001.TT.5491, Transport Engineering and Logistics.

This report gives a broad view of baggage handling on airports. Although the time required to sort and transport luggage often prevents flights being thighter scheduled, baggage handling is often underestimated considering design and extension of airports. The continuing growth of airtraffic has to be handled by a small number of airports that is forced to expand. The expansion causes an ever growing amount of luggage to be transported over increasing distances. This greatly affects the process of baggage handling.

Many baggage handling systems transport 'raw' baggage. The conveyability of raw baggage is extremely bad due to the different attributes of luggage. This causes the big airports to transport baggage in tubs (or: totes / trays). The so called 'tubbing'. Baggage that can not be dealt with automatically even in tubs, is called: oversized, oddsize or 'out-of-gauge' (OOG). This baggage forms a separate flow that in itself is not efficent but does not effect the capacity of the automated system. Efforts to further increase the amount of baggage that can be dealt with automatically, are not worth the price. The most critical baggage flow consists of transferbaggage; very often this baggage determines the 'minimun connecting time'.

The baggage is labeled at check-in so it can be identified automatically in the sortation system. The IATA label is the nowaday standard. The error percentage while reading this label automatically lies between 3 and 50 percent. Radio Frequency IDentification (RFID) is supposed to be the next standard. Its only disadvantage being the high costs, but RFID chips are getting cheaper. More and more the passanger has the possibility to check-in his baggage early. This spreads the flow of orginatingbags better but requires an 'early-baggage-storage'(EBS). Due to strict safety measures it must be possible to approach luggage in the EBS quick and even individually. If the tubs are strong enough, conventional storage systems can be used. 100% Hold baggage screening (HBS) is compulsory by the end of 2002. New scan techniques and better image processing makes online scanning possible without any effects on the capacity of the baggage handling system.

The concept of the airport terminal buildings greatly affects the design of the baggage handling system. American airports mostly consist of a number of highly independent terminals with their own ( decentralised) baggage handling facilities. These facilities are often simple and a great deal of manual sortation is done. Passengers often have to transport their luggage themselves from the one terminal to the other. More and more passengers do not accept this and airports are trying to link their terminals. These links often do not cover the whole airport and transportation distances are long. The European airports are strongly centralised and the baggage handling systems are highly automated. When an airport has to expand beyond the radius of the central terminal building, the so called 'satellites' arise. Transport distances and the necessary transport velocities increase greatly in case of satellite terminals. Simulations have proven the transport distances to be the smallest in case of linear midfield terminal concourses.

The baggage handling process can be divided in 'inbound' and 'outbound'. It looks if inbound, the handling of arriving baggage, is optimised: the tranfermix is manually sorted while loading the majority on the reclaim caroussel and the passengers sort the destination bags themselves. The originationg bags have to be sorted after destination, class, transfer or not, etcetera. It depends on the size of the airport if sortation can be done manually or has to be done automatically.

The sortation process consists of: order selection; premerge accumulation; merge; induction; takeaway.
Merge and accumulation are not possible when handling raw baggage due to the possibilty of jams. Raw baggage has to be sorted as passive as possible on a closed conveyor surface. Suitable for transportation are also only beltconveyors. Suitable low to medium rate sortation equipment is in fact only the specially developped vertisorter. Because of the lower costs and smaller dimensions the less suitable pusher sorter is most widely used. The only suitable high rate sorters are the tilt-tray sorter and Destination Coded Vehicles (DCV).
There are no restrictions in suitability of low to medium rate sortation equipment if baggage is conveyed in sufficient strong tubs. Although in that case there are no restrictions in high rate equipment too, again only the tilt-tray and DCV are really suitable. Most high rate baggage sortation systems consist of a tilt-tray sorter with beltconveyors for short distances and baggage tugs and carts for long distances. DCV systems are gaining, however, due to their much higher transport velocity. This higher velocity is of growing importance with the expansion of the airports. Furthermore, as already mentioned: more and more main airports are considering 100% tubbing to improve conveyability, create efficient EBS and improve tracing: every piece of baggage should be approachable individually as long as possible. It seems also logical to send luggage in its own tub on a route dependable of its destination through the system: Destination Coded also. Frankfurt is the best example of such a system. This system has a number of disadvantages, however, like high energy consumption and wearing, that a Destination Coded Vehicles system does not have.

The transportation velocity of a DCV systems is higher than of a tilt-tray sorter system. Furthermore the availability ofa DCV systems is higher: The whole tilt-tray sorter has to be running to sort only one bag, while only one DCV has to ride to deliver one bag; energy consumption is also lower with a DCV system. This in combination with the higher availability makes the running costs lower with a DCV systems than with a tilt-tray sorter system. Knowing this makes the major disadvantage of DCV systems: the very high investment costs less impressive.
Nevertheless: a DCV systems will only be interesting facing very long transportation distances, in case of major airtraffic hubs, also. A limit of 40 million passengers pro year has been found in literature: above this limit a DCV system should be preferable above a conventional tilt-tray sorter system. It lies beyond the scope of this report to prove this this limit; the comparision has been made qualitatively only.

Reports on Transport Engineering and Logistics (in Dutch)
Modified: 2004.04.01; , TU Delft / 3mE / TT / LT.