Policy oriented emission factors for road freight transport

Impact assessments of carbon emission mitigation policies by shippers and carriers require appropriate emission models and indicators of logistics activity. Usually, the ton-kilometer indicator is used to measure logistics activity, and emissions are calculated as a linear function of this indicator. Generally, the models that emission factors originate from are unknown. This makes their application difficult, especially when interdependencies between measures must be considered. Here, we develop a policy oriented framework of simplified emission factors that are derived from internally consistent, comprehensive models, are applicable to the various measures by different logistic actors and are as easy to use as the usual ton-kilometer indicator. We identify a set of emission factors by taking simple first order derivatives of two comprehensive models proposed in the literature, the EcoTransIT World Model and the Ligterink model. The approach allows us to compare the models and discuss the effectiveness of our framework for alternative mitigation strategies. We position the emission factors of the first as a specific case of the latter model and discuss the bounds of the applicability of emission factors from the two models.