Deterministic and stochastic carbon footprint of intermodal ferry and truck freight transport across Scandinavian routes

Intermodal transport is the transport of cargo using one single unit by at least two different modes. Previous research suggests that intermodal transport might lead to emissions savings when traffic is shifted from high- to low-emission vehicles. This study aims to test this hypothesis by comparing intermodal truck-ferry routes and road-only routes within Scandinavia. The environmental performance of 66 routes in eight transport corridors was assessed in terms of carbon footprint using methods, databases, and software from the Life Cycle Assessment domain. To improve the robustness of the comparison between alternative routes, stochastic error propagation was applied to obtain a distribution of carbon footprint values for each route and pairwise statistical tests were performed between these distributions. Shifting freight traffic on ferries leads to emission reductions which size depends on the route, ferry type, and fuel used. Long distance routes by sea must sensibly cut road distance to allow for net emission reductions. The use of ferries transporting cargo only and of liquefied natural gas-powered ferries is highly preferable to the use of ferries carrying both cargo and passengers and of diesel ferries. The results can support the decision making of different stakeholders within the freight transport sector interested in lowering their carbon footprint.