Data are collected from Ministries of Transport, national statistical offices and other institutions designated as the official data source. The survey used for this exercise is the "Investment Spending in Transport Infrastructure". The original data is collected in national currency, current values. Data are converted and published in euros, both current and constant (2015 prices). The variables collected include investment, maintenance spending and capital value of road, rail, inland waterways, maritime ports and airports. Data are published annually on 31 March. Data series start in 1995 and continue until the current year-2, or the most recent available data.