In logistics research, there has been a focus on measuring the absolute performance of road
transport operations. However, there have not been any studies assessing the marginal impact
of supply chain disturbances on the economic and environmental performance of such
operations. Starting with the assumption that any unnecessary distance run creates a
proportional additional cost and output of carbon dioxide, the aim of this paper is to introduce
the concept of ‘extra distance’ as a means of assessing the marginal impact that deviations from
the transport plan have on the economic and environmental performance of road transport. An
inductive research approach has been adopted, including the empirical application of the
concept within two supply chains. From this, five types of ‘extra distance’ are identified and
linked back to the concept of uncertainty within transport operations. Therefore, ‘extra distance’
can be considered a novel diagnostic measure that can be used to evaluate the causes and
consequences of uncertainty within distribution networks.