From a Vauxhall Velox

Her mother read her mail

And her Dad was a Policeman

Which I must say worried me

But some things have just got to be

So we passed very fast like ships in the night

Or cars in a contraflow system

-- Billy Bragg, From a Vauxhall Velox

Not only is this a perfect simile, it's goddamned ballsy to drop a term like "contraflow system" into a pop song.