I've asked this question before myself. What I found was, the streets are swept twice a year, once in the spring and once in late fall AFTER all of the leaves are down. With the cost of labor, equipment and gas for the 1000's of miles of city streets that is the most efficient schedule. I agree, it takes weeks for the leaves to fall and it would be way too costly to send trucks out for individual streets as leaves gather. The routes need to be planned so that a large section of the city can be done on one work shift. Next night another section of the city and so on. Have you noticed the streets are swept overnight? Again, I think this is good planning. It would cost so much more to sweep the streets during the day when traffic would hold the trucks up, taking longer to get the work done adds to labor hours and moving slowly by hold ups in daytime traffic would cost more in fuel. These are all expenses to each of us, so I tend to let the road crews follow the procedures they've used for many years that do seem to work well. The routes, route numbers and schedules were all explained to me but sorry I've forgotten those details. You could call the city and ask what route you're on and when your section is scheduled for sweeping, then make a note on NEXT years calendar for a reminder as the routes and timing will pretty much be the same next year. Hope some of this helps.