D5 Annex report WP 4 - ETIS plus

D5 Annex WP 4: ETIS DATABASE METHODOLOGY AND DATABASE USER
MANUAL – PASSENGER DEMAND
generate vectors of originating per capita journeys (O(x)­Vector), one per trip purpose business
(x=B), private (x=P) and holidays (x=H).
The input for the generation models come from various sources and covers regional indicators
of demography, economy, environment and location. These indicators had been identified, as
being the determinants of transport demand.
The estimation of non­linear model specifications on the base of household survey data resulted
in parameters giving the influence of the determinants and their interdependencies.
The O(x)­Vectors coming from the generation stage are fed into the corresponding distribution
models which raise the per capita number of journeys to the total amount of originating
transport demand and spread the outgoing number of journeys between the available
destinations. The result is an asymmetric origin­destination matrix per trip purpose (OD(x)­
Matrix). As in the generation stage, the distribution within space is also determined by regional
indicators that express the attractiveness of a certain region to being visited by travellers from
the origin. Here population, economic situation, climate and landscape are the ‘attractors’ of
journeys. The sequence of model steps is completed by the choice of transport modes and the
assignment to the network representations.
The individual­based model approach and the resulting asymmetric flow matrices allow a better
calibration of the model system than classical approaches do. Due to the impossibility to
separate generating and attracting effects in the classical ones, the calibration attempts suffer
from lacking detail in specification as it is not always clear if e.g. a bias in the level of transport
flows is owed to the amount of originating traffic or its spatial distribution.
The following subsections will describe briefly the basics of the generation and distribution
steps.
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Document3
27 May 2004