The Comparative Environmental Performance of Freight Transport Chains - Why Do the Models Provide Different Answers?
H M Hjelle, Molde University College, NO
Models developed for analyzing the comparative environmental performance of transport chains provide very different answers. Why is this so? This paper reports on a comparative analysis of such models.
Choosing optimal transport chains from an environmental perspective is a key challenge for operators, cargo owners and policy makers. Various models have been developed to assist actors to assess the environmental performance of alternative transport chains. Some of these models are “in house” models of prominent transport and logistics companies – often promoted as an extra service to customers, others have been developed for open access and public use.
When applying the various models to the same set of transport alternatives they seem to provide quite different answers. Why is this so? Could the differences in output be explained by studying the documentation of the models? The research reported on in this paper investigates to what extent the existing models actually do provide different answers, then analyses to what extent the models are well documented, or appear to be “black boxes”. The documentation provided is then analysed with the aim of identifying weather the different outputs could be explained by the empirical evidence upon which they are founded, by the type and level of simplifying assumptions encompassed in the models, or other factors.
The models chosen for this analysis represent the ones frequently used in European settings. A comparative analysis of the models is conducted – both with respect to application area, e.g. weather they cover all transport modes, by the kind of cargo they cover, by functional units applied, and by the level of transparency of the documentation offered. The models also differ quite a lot with respect to the range of environmental performance indicators covered. Subsequently, the respective models are applied to the same set of constructed typical intra-continental European long distance cases of transports and the differences in environmental performance output data is described and analysed.
Association for European Transport