I have a brick patio that tends to get overrun with weeds, especially at the edges. I've trained my chickens to follow me and I lead them over to the patio, sprinkling yummy seeds into the patio weeds. They scratch it up pretty well looking for the seeds.
All of my land is sloped so as the chickens clear the land they rake the dead grass downhill. This means that the fence line on the lower part of the paddock collects seed free, pest free, fertilized shredded mulch. All I have to do is rake it up and throw it around the forest garden areas. I have a constant supply through the season as the chickens move from one paddock to the next. When I have garden scraps and kitchen waste, I add it at the highest point in the paddock.
The coop is also set up so that one side of it is up off of the ground by about a foot. The coop has no floor so all the night manure gets kicked down hill and out of the coop without me having to mess with it. I just throw in a little dried grass and wood chips from time to time to encourage them to keep the material moving through.
In the fall they go to work in the gardens clearing weeds, seeds and pests.
Cars will tend to slow down if your chickens are ranging near the road. Beware: Dumb chickens might not get out of the way of a car.