This is a way to keep your chickens where you want them and lets them have more freedom and access to more bugs and weeds. It is a win win situation, chickens want to roam free, but we want to keep the out of flower beds and off of walk ways where their droppings are a nuisance. So these chicken tunnels make sense. You can wind the chickens out to a certain area where you can open up a fenced area where they have lots of freedom and then tunnel them back, avoiding areas like flower beds and garden plants.
When the chickens have eaten enough weeds and bug in their path the tunnels can be moved over a couple feet to allow a new path of weeds or grasses to munch on. In the mean time the original path can be recuperating and getting ready for the next attack from the chickens. It could even be used as a lawn mower if you have enough chickens and the tunnels are mobile enough to move as needed. The best thing about this process is the freedom the chickens get, they move around and are not cooped up all the time. At the same time they are safe from other animals and they wont get lost either. Great for the chickens! Here are some pictures of how these tunnels look and are made. Click the link below for more info.