A park near my house has a narrow-gauge railway setup.
Check out the trains.
That's a full-size train track in the background on the other side of the chain-link fence.
The "diesel" locomotive runs off a lawnmower motor. This, however, is a live steam engine. The owner had to build a fire inside the boiler compartment and let steam pressure build for almost an hour before moving it onto the rail system at the park. Note the coal car just behind the locomotive. Sure enough, there's a pile of coal in the car and he'll stoke the fire occasionally as he takes the train around the track, which is a circuit of a little over a mile.
The steam engine is a bit short on power. He'll add two cars to the back on which to carry passengers. The most powerful train at the park can pull up to 10 cars.
These locomotives didn't come out that day. I caught them in their storage locker. The models are built pretty closely to scale in terms of power, and incredible attention is paid to accuracy in terms of the powertrain and braking systems.