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

D5 Annex WP 3: DATABASE METHODOLOGY AND DATABASE USER MANUAL –
FREIGHT TRANSPORT DEMAND
Table D.2
Example of Container Registration
Mode Container Meaning
Sea
Road
Yes
No
Commodity transported over sea in a container
Commodity transported by road not in a container
A possible extension to this method is to include also a type of container (large, other) on the
place where otherwise a ‘yes’ would occur. Still a further extension would be to include in stead
of a variable for container only, a variable for classification of loading units types.
Should there be a Restriction on the Number of Links in a Transport Chain?
Combining all the solutions in the previous paragraphs for the problems encountered in the
computer example we see that for registering one flow, many variables are needed. If we take a
look at the transportation of the computer from point A to point F we see that six locations have
to be registered. One origin, four transhipment locations and a destination. Also five modes (one
for each link) have to be registered together with the passive modes and container indications.
This means 21 (= 3 x 5+ 6) variables are necessary for this transport chain. Furthermore
variables are needed to describe the commodity, the weight and the value. Many transport flows
will be less complex but there will also be more complex transport flows meaning that even
more variables are needed.
A partial solution to reduce the size of the database is to use a dynamic data structure in which
for every transhipment place a variable is ‘made’ in the software. This means that sophisticated
software has to be developed. The flow structure however still will be complex and difficult to
comprehend.
Another more pragmatic solution is to restrict the number of links. This also has disadvantages
however, since it is important in case of inter­modal transport to describe all transhipment that
takes place. Furthermore reducing the number of transhipment points in the database also has
some negative impacts on the reliability of the information to be extracted. To get more insight
in this a look will be taken at the example in figure 5.4
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27 May 2004