Who is responsible for maintaining trees in a residential zone?

There are hundreds of properties throughout the town with trees and other vegetation encroaching into streets and sidewalks with limbs that block signs and signal lights. These tree limbs are hazards and can force vehicles into other lanes, force pedestrians and cyclists into the streets, and can cover important signage. If an accident occurs due to the encroaching vegetation, the town would not be at fault, but rather the property owner would assume responsibility. Therefore, regular maintenance on resident owned vegetation is vital to the health and safety of the town.