Több helyen is utánanéztem, majdnem mindenhol a mauritániai vasércvonatot írták (vastagítás tőlem):

The train carrying iron from Zouerate to the coast at Nouadhibou, is probably the world's longest train. Normally its length is as much as 3 kilometres. The whole journey takes around 12 hours, where almost 700 kilometres are covered.

Aztán megkukkantottam a http://www.guinnessworldrecords.com/ -ot; egyszerű keresésre rögtön előjött:

The longest train ever was 7,353 km (4,568 miles) long, and consisted of 682 ore cars pushed by 8 powerful diesel-electric locomotives.Assembled by BHP Iron Ore, the train travelled 275 km (171 miles) from the company's Newman and Yandi mines to Port Hedland, Western Australia, on June 21st, 2001.