According to Wikipedia, a dead end, also known as a cul-de-sac, a no outlet road, a no-through road or a no-exit road, is a street with only one combined inlet and outlet. Dead ends are added to roads in urban planning designs to limit traffic in residential areas. Some dead ends prohibit all-through traffic, while others allow cyclists, pedestrians, or other non-automotive traffic to pass through connecting easements or paths. The latter case is an example of filtered permeability.