The study is aimed at determine standard scales of unit costs (SSUC) for travelling within the EU and from any country in the world to EU countries in order to simplify the reimbursement system and enhance its use among European administrations. Collected data will be exploited for statistical analysis - relevant for the definition of the standard scales of unit costs - through descriptive statistics and data visualization. The calculation of the punctual unit costs for travel between pairs of destination within EU and worldwide to EU defining the methodology will be made, the structure of the standard scale of unit cost (e.g. distance ranges, type of frequencies of itineraries, modes of transport) will be identified, and the form of expression of the unit costs (e.g. per Km, per distance cluster, per Km/ distance cluster) will be defined. Finally, specific indications will be also provided with reference to the practical application of the Unit costs resulting from the calculation methodology, as well as to their update