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

D5 Annex WP 3: DATABASE METHODOLOGY AND DATABASE USER MANUAL –
FREIGHT TRANSPORT DEMAND
Ideally, it would have been possible to use just the 1996 survey, which was partly funded by the
STEMM project (DGVII), but experience has shown that this survey contains deficiencies. In
order to complete the freight modelling work within the STEMM project, the survey data was
enhanced by contributing data from other sources such as the 1996 International Road Haulage
Survey (IRHS) and the Railfreight Distribution database. Finally it was grossed up using UK
trade data for 1996, and given greater regional strength by incorporating parts of the 1991
ODIT, which had a stronger methodology. (See STEMM Report).
The ODIT source is essentially a record of unitised trade flows only as the consolidation of
bulks in port silos and tanks makes it very difficult to match origins to destinations using a
questionnaire approach. It was not considered sensible to estimate the inland origins and
destinations of such commodities.
Regional data is collected at the county level (NUTS3). Problems have been encountered in
mixing basic data from different years, as a series of changes have occurred in the definition of
county boundaries. However, in aggregating to ten NUTS1 standard regions, (excluding
Northern Ireland) these inconsistencies have been removed.
Building Region­Region Matrices: The Problem
The final stage has been to tackle one of the classic transport problems which is how to convert
data of the form:
Region R1 (belonging to Country C1) to Country C2: T1 tonnes.
Region R2 (belonging to Country C2) to Country C1: T2 tonnes.
Into:
Region R1(in C1) to Region R2 (in C2) : T3 tonnes.
The problem can be observed as an origin­destination matrix where the row and column totals
are known, but the individual cells are unknown.
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27 May 2004