I'm going to pretend that Balling the Jack has jack all to do with trains, simply because it's more fun.
The addition of the jazzier chords in the verses and breaks are a sweet juxtaposition with the straighter harmonies in the chorus. Sweet arranging. The band is classy. Janice sings all loosy and takes it home on that long slide. Grease to the rhythm of the wheels. (Just not train wheels.)
Hugely enjoyed.