An electric railway for the transport of passengers with the capacity for a heavy volume of traffic and characterised by exclusive rights-of-way, multi-car trains, high speed and rapid acceleration, sophisticated signalling to allow a high frequency of trains, and high platform load.
Metros are also characterised by frequent stations, normally meaning a distance of 700 - 1 200 m between the stations.
Note:"High speed" refers to the comparison with trams and light rail, and means here approximately 30-40 km/h on shorter distances, 40-70 km/h on longer distances.
Also known as "subway", "metropolitan railway" or "underground".
Glossary For Transport Statistics, Eurostat, ECMT, UN/ECE, Third edition