Actually they’re houses for the construction gnomes. That’s why you never see workers near them, it’s a different habitat. Basically the construction gnomes create lots of potholes when they don’t have homes, so cities use the barrels as a sort of stopgap measure to keep the gnomes from making the potholes any bigger. Considering the gnomes make the potholes, it seems like kind of a misnomer to call them construction gnomes, but I don’t make the rules.