http://www.brooklynrail.net/science_of_railway_locomotion.ht...

Which has the comment: At the same speed, same load (GCW) and on level ground, any steel wheeled railway vehicle is 24.6 times more energy efficient than any large rubber tire road vehicle, regardless of the type of power source.

My hand wavy argument would be, to go 300 miles a passenger car needs 33% (guess) of it's weight to be batteries. But a truck is probably 2-2.5 times more efficient. So would only need 33% / 2.25 (split the middle between 2 and 2.5) or 15%.

If a 4000 ton train is 25 times more effecient than a truck as started above then. 15%/25 is 0.6%.

So the battery for a 4000 ton train would weigh 4000 * 0.6% -> 24 tons.

Seems to pencil out to me.