“All transport costs that are not covered by users, including all kinds of externalities, infrastructure costs or different regulation”.
Source: European Environment Agency. 2007. "Size, structure and distribution of transport subsidies in Europe". EEA Technical Report, No 3/2007. EEA, Copenhagen, Denmark. <https://www.eea.europa.eu/publications/technical_report_2007_3>. Accessed 14 April 2020.