One locomotive weighs about as much as 108 hippos These 6-axle engines have 4,400 traction horsepower and can reach a maximum speed of 70 miles per hour pulling thousands of tons of freight.

The speed of a single train engine depends heavily on its type and the track infrastructure it is designed for. The world record for a traditional electric locomotive is held by the Siemens ES64U4 (EuroSprinter), which reached a top speed of 357 km/h (222 mph) in 2006. Standard modern freight locomotives in the U.S. typically operate at much lower speeds, usually capped between 60 and 70 mph, though they are mechanically capable of going faster without a load. High-speed passenger "power cars," which are essentially specialized engines, can easily sustain speeds of 186 to 220 mph in commercial service. Experimental engines and maglev "pods" have gone even faster, with records exceeding 374 mph. For everyday rail travel, most single engines are governed by safety regulations and track quality rather than the absolute limits of their horsepower, ensuring that the engine remains stable and efficient while navigating curves and junctions.