Locomotive Weight & Horsepower

[CSXfoamer1997]

Why are freight diesel locomotives currently limited to about 230 tons and 4,400 Horsepower despite engines becoming cleaner and more fuel efficient with their designs?

In theory, I think if GE or EMD create a 300- or 350-ton diesel locomotive, it could pull even longer trains with just one locomotive. In fact, imagine if a 500-ton diesel locomotive was built!

The current record for diesel locomotive weight is the Union Pacific DDA40X, which weighed 244 tons. But the heaviest of all locomotives was the UP Coal GTEL (which consisted of a diesel loco and gas turbine-electric unit), which weighed 728 tons! And also, the Union Pacific 8500-HP GTEL's (Big Blows) weighed 425 tons and had a tractive effort of 944 kN's!

 

[NW cannonball]

Uh - because the track and structures are designed for 37 or so tons per axle max? Because having two traction units sharing the load means fewer main-line blocking failures? Because having more than 12 powered axles on a loco needs some unexplored design problem to be solved -- like how to make the trucks track and pull at the same time? Stuff like that. Just practical engineering .