It's hard to say. Maybe there are elements inspired by real events, but it could also be largely fictional. You'd need to look into the background and creator's statements to get a clear answer.
One main aspect is the volunteer effort. People volunteer their time to clean up the highway. Another is the environmental benefit, as it reduces the amount of trash on the roads. Also, it promotes a sense of community among those who participate.
One possible plot could be a group of volunteers coming together to clean up a neglected highway. They face initial resistance from local authorities but manage to convince them of the benefits.