A cul-de-sac or close is a dead-end street with only one inlet/outlet. While historically built for more random reasons, its modern use is to calm vehicle traffic. It has also been accused of creating communities which require the use of a car and are badly connected for pedestrians and cyclists.
In traffic engineering parlance, the cul-de-sac defines the local street as having primarily an 'access' (to properties) function rather than as one having a 'transport' or 'through' function.
The use of culs-de-sac reduces the amount of car traffic on residential streets within the subdivision, thus reducing noise and, allegedly, the potential for accidents. This, in turn, is thought to decrease crime and increase desirability, because in most cases the people who traverse the cul-de-sac either live there or are guests of those who do. Real estate developers like culs-de-sac because they allow builders to fit more houses into oddly shaped tracts of land, and facilitate building to the edges of rivers and property lines. Culs-de-sac also facilitate gated communities, because of the small number of entrances.
Houses on culs-de-sac may be popular with some buyers, who, according to one study, might pay a 20% premium for such a home.
More recent evidence suggests that the traffic reduction provided by a cul-de-sac may allow misbehaviour in the street that a through route would tame by the risk of being spotted by passing motorists. However, this runs counter to the theory of Crime Prevention Through Environmental Design, which would suggest and has demonstrated that a single method of escape leads to a decrease in crime.
More generally, the New Urbanism movement has offered criticism of the cul-de-sac and other streets not intended to network with each other. It has been suggested that such street layouts can cause increased traffic on the non-cul-de-sac streets, make navigation (especially on foot) inconvenient and non-intuitive, and reduce the size of any given neighbourhood to a single street. This applies especially to back-to-front housing where the front of the house fronts onto the cul-de-sac lane while the rear fronts onto the main roads. Some of these problems can be mitigated by the newer practice of connecting the neighbouring roads and culs-de-sac with public pedestrian/cycle paths. In effect, this removes the cul-de-sac aspect for these modes of transport. Built examples of such connected culs-de-sac can be found in the United States (e.g., Radburn, New Jersey and Village Homes, California), England (e.g. Town of Milton Keynes), and Greece (e.g. Papagou, suburb of Athens). A new system for organizing connected culs-de-sac, the Fused Grid, has been developed by Canada Mortgage and Housing Corporation.
Another concern is often raised by emergency services, who can have difficulty locating streets when a community consists of a large number of similarly-named culs-de-sac; also, large fire response vehicles, in particular, can have great difficulty with turning around in a cul-de-sac.
School buses can have also have a hard time turning around, which means that children who live in a cul-de-sac must often walk to a bus stop on a main through road. However, recent research on obesity and urban planning suggests that this may be an advantage because it enables children to get daily physical activity. Longer walking distances, however, reduce interest to use buses especially when a car is available.
Despite seeming to be a borrowed French phrase, the expression cul-de-sac originated in England during the period when French was spoken by the English aristocracy. "Cul-de-sac" literally means "bottom of a bag" in Catalan. J. R. R. Tolkien used the name Bag End as a literal translation of "cul-de-sac," to poke fun at the British use of French terms.
In modern France, culs-de-sac are called sans issue, "which translates, sort of, as 'no way to the egress'", according to Michael Oreskes, editor of the International Herald Tribune, based in Paris. For signage, European countries use a graphic symbol somewhat like a "T" rather than a sign with words,.
«Lecteur, si je faisais ici une pause, et que je reprisse l'histoire de l'homme à une seule chemise, parce qu'il n'avait qu'un corps à la fois, je voudrais bien savoir ce que vous en penseriez? Que je me suis fourré dans une "impasse" à la Voltaire, ou vulgairement dans un cul-de-sac, d'où je ne sais comment sortir.»
"Reader, if I have put a pause here, and that I continued the story of the man with a lone shirt, because he had only one body at any one time, I would like to know what you would think? That I lost myself in an "impasse" à la Voltaire, or vulgarly a cul-de-sac, from which I don't know how to leave."
In military parlance, a "cul-de-sac" refers to a situation where an army is "hemmed in on all sides but behind" "Cul-de-sac" is also used metaphorically to mean a line of thought or action which leads nowhere.
New York City has favored "Dead End" since at least the 1930s, when Sidney Kingsley used the phrase to title his Broadway play about poor, tough East Side youths with lives of little promise, in contrast to the nearby dead-end streets of the nearby Sutton Place neighborhood. (Similarly, French existentialist Jean-Paul Sartre titled a play about three damned sinners, Huis Clos, translated into English as "No Exit".) Kingsley's play, later made into a movie, Dead End, which proved so popular that it spawned similar movies, many staring a group of recurring characters known as the Dead End Kids. The play and movies created such a strong image of bleak futures and an unfair society that some municipalities changed the sign terminology for culs-de-sac, often to "No Outlet" or "No Exit." (The "Dead End" signs currently at Sutton Place are bright yellow with black lettering.)
In Canada and the United Kingdom, "No Exit" is prevalent, and the word is preferred for Chicago signs, although "Dead End" is still used there. U.S. Federal Highway Administration rules state: "The Dead End sign may be used at the entrance of a single road or street that terminates in a dead end or cul-de-sac. The No Outlet sign may be used at the entrance to a road or road network from which there is no other exit." There is no federal regulation on "No Exit".
In New York City, as of 2008, there were 4,659 "Dead End" traffic signs, along with 160 "No Outlet" signs. The city records, which go back to the 1960s, show only a couple "No Exit" signs once existing near the approaches to the Midtown Tunnel, and which are no longer there. "We hear that some towns use 'No Outlet' instead of 'Dead End' because they think it sounds less morbid," New York City Commissioner of Transportation Janette Sadik-Khan said in 2008. "We tell New Yorkers the truth: it's a 'dead end', and we think that motorists get the point quickly."