Freight trip generation is the first step in the 4-stage model. Trip generation may refer to different areas (e.g.
part of a city, commune, district) or particular objects (e.g. single generators). In road freight transport trip
generation may be estimated either by the number of vehicles (vehicle based model) or the amount (tons, value)
of commodity (commodity based model).
In commodity based models all modes of transport are considered. In particular, in road freight transport
commodities are transferred to trucks using average payload factors. On the other hand, in vehicle based models
mode split is conducted with trip generation, where trip generation rates or equations are defined for each type of