We’ve seen many transport forms hit towns and cities in recent decades. Yet, trains have still reigned supreme. I mean, they are one of the most preferred forms of transport in the world! But as it turns out, some are just a bit more special than others. From the largest privately owned rail structure to the longest and heaviest freight train, here are 15 largest trains in the world.

 If you need 12 engines to pull a record-breaking train, wouldn't it be more efficient to cut it in half (or thirds, or quarters) to reduce the train building-time and loading/unloading logistics Rather than sit around and wait for the monster train to be built, send smaller trains when they are ready. It would require more drivers ...
 22:01 I can almost guarantee something is wrong with this fact. The railway is 250 km long, but the trains are somehow a staaaaggering 2950 km long! That is an insane insane length for a train! I think you probably meant meters. I seriously doubt this train is 2 950 000 yards long
 At 22:06 each train was 2,950 kilometers long !!. I think that he means meters.  The whole rail line is only 260km.
 4:15 I thought The Big Boy hauled a five-mile train over the Allegany Mountains. Two Challengers couldn't do it, but for the grade, they would hand off to the 4-8-8-4 which did.
5:04 Could have said... As heavy as 2 USS Iowa battlesships.
 Look up the Laggan Subdivision between Calgary AB and Field B.C. The final 10 miles is 2%+ grade with two spiral tunnels that were constructed over 100 years ago. 25,000 ton+ trains run there.  Very satisfying watching this video about  trains. I feel like a kid watching electric toy trains going round and round