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

D5 Annex WP 3: DATABASE METHODOLOGY AND DATABASE USER
MANUAL – FREIGHT TRANSPORT DEMAND
are consistent. In case the port to port data would have been available a multidimensional entropy
method could have been applied to combine all sources.
From this exercise we learned that combining sources is useful in any case to ensure consistency,
but that the reliability is in the first place depending on availability of data for all elements of the
chain.
One of the main advantages of a top­down approach is that detail can be added to the database by
inclusion of different sources on specific transhipment points or links without being held back by
the non­availability of data on other transhipment points or links. A danger might be that in case the
information for the construction of a transport chain is incomplete, like was the case in the example
above, unreliable links can be included. In these cases it is important that these links can be
identified in the database or that the main database can only be approached by trained experts and
that sub­sets of the database constructed by aggregation of one or more variables will be available
for a wider audience.
4.5 The top­down approach
The philosophy of the “transport chain principle” implicates that the transport flows are
determined by the trade flows; we preserve the trade relation and follow the route of the
transported goods. This means that, besides the origin and destination, the location of
transhipment and the modes before and after transhipment are included. To do this we use a topdown
approach, which means that we take the rough country­to­country trade information and
refine this, step by step, using the various national data sources. This approach allows us to
introduce the most disaggregated level permitted by the data sources available in each
individual country, without being limited by the lack of data in other countries. By constructing
the database using the top­down approach, it is possible to use a restricted number of sources with a
maximum of regional detail. Additionally it is possible to give different parts of the database a
different level of detail without introducing inconsistencies. This method is being materialised in an
approach in which four phases can be distinguished.
The phases in the top­down approach are the following:
1. The building of a country­to­country matrix
2. Including transhipment regions on the basis of transhipment statistics
3. Regional division of country­to­country totals
4. Incorporating domestic transport
These phases will be described in the following paragraphs.
4.5.1 Phase I The construction of a country­to­country matrix
As a reference for the development of the database the EUROSTAT trade by mode (COMEXT) is
used for the EU countries and national trade data sources for the other countries in the core area. In
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