At Energy it was really interesting because it allowed them to make the vehicles trackless before things like wifi really existed.
It works much like a metal detector - pings when right over the wire, faint when near, and nothing when totally off. However instead of just pinging it's relaying info to the vehicles, like playing a song with instructions (like the Macarena so to speak.) Each vehicle is like a dancer and knows it's assigned role in the show setup. When the wire gives the cue it scoots along. If it loses the signal it stops.