The ITRD is a co-operative world-wide database of information. It has been in existence since 1972 as one of the major activities of the OECD Road Transport and Intermodal Linkages Research (RTR) Programme. More than 300 000 scientific references can be found, each with an informative abstract from the world's published literature (reports, books, journal articles, conference proceedings) together with summaries of ongoing research. About 10 000 references are added each year.