Trolley Poles
Aside from being less “iconic”, the new TTC Flexity Outlook rolling stock is also unique in having both a trolley pole that sticks up like an antenna at the back and a pantograph which rises from the top-center.
Why do the “new” Flexity cars have pantographs? Pantographs are the default configuration of the Flexity and the defacto standard for overhead power coupling. Pantographs work better at high-speeds, don’t need to be exactly centered over the vehicle, don’t need complicated “frogs” for intersections, and are generally more common; they’re the natural choice. So the new TTC have pantographs because they’re generally accepted as better.
Why do they still have trolley poles then? Because most of the TTC network has overhead wiring built for trolley poles. Pantograph and trolley pole wiring look pretty interchangeable, but they’re not exactly. Trolley pole wiring needs to be closely aligned with the center of the vehicle to keep the tracking wheel from jumping off the wire while pantograph wiring needs to zig-zag from side to side so the wear on the patograph’s collector bar is even and similarly trolley poles do a better job following changes in wire height while pantographs typically require a tighter tolerance, but neither is a severe factor at low speeds. The main problem is trolley pole wiring only requires that the wire itself is accessible for the wheel while pantographs need no objects lower than the wiring for the entire width of the pantograph (so they don’t hit anything or short two different circuits); it is this new requirement for pantograph service that keeps the TTC’s trolley poles in existence.
New TTC tracks are built with Pantograph friendly wiring but the majority of the network still needs work — so, for today, the Flexity cars are reconfigured depending on the route.
This is all heavily cribbed from the much more in depth articles on this subject and TTC history as a whole:
