This would be awesome but I see some difficulties here due to the continuous variations in cars, structures, and other things related to the trolley/streetcar lines. Every company had their own shop and made or customized to the hilt, the cars they purchased.
There are ways around this if you want to choose a specific route and car-type such as the PCC trolleys. Then again different cities had their own flavor of the slightly varied PCC cars. Boston's cars are different than San Francisco's which are different than Toronto's cars. A paint scheme change may do it in some cases, but not in all especially if the window-style is different.
For roads and wires, I've used the SAM series tram-track. The German kids have made some awesome track and so has ptram which you can download from his website. Ptram's street track has the wire already in place, so all you need to do is add poles. The tracks are nice and thick and match up well with the YARN roads. Usually track sticks up above the roads or floats, but the YARN roads are thick, don't float and the track fits right into them.
There are two kinds of poles, those that are a spline and have the wire already attached, and those that are trackside objects which you line up easily and then drag spline-wires along. Paulzmay has made some awesome kits which include poles and wires. Both are separate units and get placed individually.
John
