This paper describes the methodology used to model overall Australian vehicle travel demand until the year 2015 and then to make projections of diesel vehicle travel, diesel fleet vehicle numbers and diesel emissions for the four main pollutants (carbon monoxide, hydrocarbons, oxides of nitrogen and particulates) for rural and metropolitan areas in each Australian state. The methodology takes into account the different emission characteristics of five vehicle types (cars, light commercial vehicles, rigid trucks, articulated trucks, buses) and the changing emission characteristics with vehicle age of these various vehicle types. In metropolitan areas emissions were estimated on three different functional road types and four different daily periods, as vehicle speeds differ in these twelve different categories and the modelling assumed that emissions varied with travel speed. Emission projections were carried out for three different scenarios; no change in new vehicle emission characteristics after 2002 (Scenario I), no change in vehicle emission characteristics after 2002 but a reduction in diesel sulphur content to 0.05% in 2003 and 0.005% in 2006 (II) and lastly, the governments Measures for a Better Environment which introduced new emission and diesel fuel standards (III). Assumed vehicle emission characteristics were revised in the light of actual emission tests on Australian vehicles in later modelling. The emission projections in Scenario I show a reduction in emissions to about 2005 arising from the turnover of the diesel vehicle fleet to better performing vehicles and then a flattening off. An improvement in diesel fuel standards (II) has a further small effect after 2003 but there is a continuing and significant fall in all emissions beyond the year 2005 under the new fuel and emission standards in Scenario III. (a)
Samenvatting