Some cities collect leaves and all you need to do is rake them into the street. The city comes around and sucks them up. I know I've lived in at least one if not two that did this - one of those cities also offered free compost to people. I seem to recall them using a street sweeper vehicle to do this with. And honestly, if you already use the street sweepers, might as well do what you can with them especially if you were simply going to have people use special lawn refuse bags for their leaves anyway.