D5 Annex report WP 3: ETIS Database methodology ... - ETIS plus

D5 Annex WP 3: DATABASE METHODOLOGY AND DATABASE USER MANUAL –
FREIGHT TRANSPORT DEMAND
1. modes at origin and destination
2. modes before and after transhipment
The records 2 and 3 result from the first decision rule and 1 and 4 from the second. Using the
second decision rule has as advantage that it is made visible what type of transhipment has
taken place. Again, due to the restriction of transhipment point loss of information occurs.
What we learn from the problems described in this paragraph is that:
· Including many variables results in a large database
· restricting the number of transhipment points implies a reduction of information (smaller
database)
· restricting the number of transhipment points implies difficult interpretation of
transhipment information
· restricting the number of transhipment points implies that clear decision rules have to be
chosen to avoid confusing results
How to include empty loading unit flows in the database?
To be able to analyse loading units movements it is also important to have information about the
empty loading units transported. How should this type of information be included in the
database? The question that arises is whether the empty loading units should be considered in
the same way as the loaded loading units or as a commodity that is transported.
Since in practice the transport of an empty loading unit is handled in the same way as the
transport of a commodity it might be more convenient to do the same in the database; in practice
one has to pay for this transport and a weight is registered for the loading unit. If the empty
loading unit is treated as a commodity, a new code could be introduced for it. If this is done it
can be treated in the same way as other commodities. A disadvantage of this method is that
empty and loaded loading units must be traced in the database in different ways. It is also
possible to introduce a variable indicating the number of containers transported. In this way the
number of loaded and empty containers can be traced by combining it with the weight
information (no weight means empty containers).
In case it is considered in the same way as a loaded container, a special code can be defined for
the loading unit variable for ‘empty container’. In case we use only one weight variable for the
whole transport chain we register the weight of the transported commodities. As a result the
weight of the transported ‘empty loading unit’ will be zero, which is a problem for both
approaches. This means that if we want to know the amount of loading units transported we
need to introduce another variable that registers for instance the weight of the loading units
transported or the total weight of the commodities plus the weight of the container.
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Document2
27 May 2004