Comparing energy use and environmental performance of land transport modes

Environmental impacts related to policy measures such as transport investments are relevant for ex ante evaluations like cost-benefit analyses (CBAs), environmental impact assessments (EIAs) and strategic environmental assessments (SEAs). However, the methodologies used in determining impacts are much less developed than those employed in estimating transport and economic impacts. The aim of the present paper is to show how rough methodologies used in current practice might lead to serious faults in estimating environmental impacts. This is followed by suggestions for improvements to these methodologies. The first suggestion is related to indicators. Since only a limited number of these are used presently, such as emissions of carbon dioxide and nitrous oxide, including more indicators might prove to be helpful. Second, changes in emissions (e.g. due to regulations) are often considered for only a limited time horizon, so extending the time horizon for emission factors is therefore an important improvement. Third, sometimes emission factors from the literature or from another country/area are used, while the circumstances are not comparable; this might lead to serious faults. Using country- or region-specific data, however, will improve the quality of assessments. Fourth, one often ignores that the effects of a given emission volume depend on the distance between source and receptor. The effects due to traffic, such as particulate matter or nitrous dioxide emissions, might then have more health impacts than emissions from industrial or power plants, and be reason enough to include these aspects as well. Fifth, it is suggested that categories of goods are broken down to determine freight modes, since lorries currently transport goods with a lower specific gravity (kilograms/volume unit) than those transported by rail and barge. The sixth suggestion calls for inclusion of indirect energy use and emissions resulting from the construction of vehicle and infrastructure. While some recommendations can be implemented relatively easily in ex ante evaluations, others will need further research.