Forty years ago there were several active traction modelers in the Cincinnati Oh area, who had very impressive pourable layouts that they brought to train shows. at that time the trolly pokes wer built up with brass castings and wires.
The wheel wasn't there just a casting representing the wheel and itls housing. the wire fit into a slot in the casting , which slid along the wire providing contact. I think I have one of these poles with a Ken Kidder streetcar which I have never used. It has a *****py motor and runs way too fast.
Bowser used to have trolley poles available, I am unsure if they still do. I will try to look around the web and see what I can find. it looks like bachman is making a single truck Briney soon. perhaps that along with the Peter Dewhit street car they already sell will help to resurrect traction modeling.
I had wanted to squeeze in some traction into the city on my home layout, but was unable to, so traction is an old itch I have yet to scratch.
Bill Nelson