A cul-de-sac or close is a dead-end street with only one inlet/outlet.

Cul-de-sac literally means "bottom of a bag" in French and Catalan. 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.

Culs-de-sac in modern urban planning

In modern urban planning culs-de-sac are created to limit through-traffic in residential areas. While some culs-de-sac provide no possible passage, others allow cyclists, pedestrians or other non-automotive traffic to pass.

Suburban culs-de-sac

Since the end of World War II,^[1] new subdivisions in America have made extensive use of the cul-de-sac. Typically, there is one or several central roads in the subdivision, with many cul-de-sacs of varying length branching out from the main roads, to fill all of the land in the subdivision. There are only a few roads (relative to the number of culs-de-sac) leading out of the subdivision, usually into other subdivisions or onto major roads. These changes can be attributed to real-estate developers' desire to meet FHA guidelines and make federal home loans available to their consumers.^[2]

This is in contrast to early 20th century American urban planning which emphasized a grid layout, partially out of wide reliance on streetcars, and alleys.

The use of culs-de-sac reduces the amount of car traffic on residential streets within the subdivision, thus reducing noise and, some think, 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.<ref name="npr" /> 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.<ref name="npr" />

Criticisms

More recent evidence with cul-de-sacs suggests that the lack of traffic 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 cul-de-sacs with public pedestrian/cycle paths. In effect, this removes the cul-de-sac aspect for these modes of transport. Built examples of such connected cul-de-sacs 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 cul-de-sacs, 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 cul-de-sacs; 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.

For these reasons U.S. cities including Austin, Texas; Charlotte, North Carolina; and Portland, Oregon have all but banned construction of new cul-de-sac-based suburbs.<ref name="npr" />

The construction of freeways has created many cul-de-sacs in both rural and urban areas since many vicinities for financial reasons want to cut back on building overpasses and underpasses of roads, and this has led to criticism of freeways.

Other uses

• Cul-de-sac is also used metaphorically to mean a line of thought or action which leads nowhere.
• Cul-de-sac is the name of a 1966 film by Roman Polanski
• In military parlance, a cul-de-sac refers to a large encirclement of troops.
• In anatomy the cul-de-sac is another name for the rectouterine pouch (of Douglas).
• Cul de Sac is a daily comic drawn by Richard Thompson

References

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