I constructed a model trolleybus system which is currently dismantled based on push-along toy buses, Scalextric track, and their car chassis, and yes, the overhead was live. In fact, in pre computerised days, having one bus using the wiring, and another using the negative wire and Scalextric pick up, you could have more than one bus operating "in section"
how about the Maypine system, a 1/3 size model of Reading 182, based on a milk float with overhead energised at 100v DC
http://www.trolleybus.net/3.htm