Trains on the railway are up to 2.5 kilometres (1.6 mi) in length, making them among the longest and heaviest in the world. They consist of 3 or 4 diesel-electricEMDlocomotives, 200 to 210 cars each carrying up to 84 tons of iron ore, and a variable number of service cars. The total traffic averages 16.6 million tons[which?] per year.
Mauritania Railway train at the station in Nouadhibou
Passengers are also occasionally transported by train; these services are managed by an SNIM subsidiary, the ATTM Society (Société d'assainissement, de travaux, de transport et de maintenance). Passenger cars are sometimes attached, but more often passengers simply ride atop the ore hopper cars.