Dead-end street

The 15th century architect and planner Leon Battista Alberti implies in his writings that dead end streets may have been used intentionally in antiquity for defense purposes:[11] The Ancients in All Towns were for having some intricate Ways and turn again Streets [i.e., dead ends or loops], without any Passage through them, that if an Enemy comes into them, he may be at a Loss, and be in Confusion and Suspense; or if he pushes on daringly, may be easily destroyed.The same opinion is expressed by Aristotle when he criticized the Hippodamian grid:[12] ... but for security in war [the arrangement is more useful if it is planned in] the opposite [manner], as it used to be in ancient times.

For that [arrangement] is difficult for foreign troops to enter and find their way about when attacking.Inferential evidence of their earlier use can also be drawn from the writings of German architect Rudolf Eberstadt, which that explains the purpose of dead-end streets:[13] We have, in our medieval towns, showing very commendable methods of cutting up the land.

I ought to mention here that to keep traffic out of residential streets is necessary not only in the general interest of the population, but, above all, for the sake of the children, whose health (amongst the working classes) is mainly dependent on the opportunity of moving about in close connection with their dwelling places, without the danger of being run over.

The proponents of the Act, Raymond Unwin and Barry Parker, thus gained permission to introduce cul-de-sacs in their subsequent site plans, and they promoted it as a suitable street type for garden suburbs.

In Canada, a variation of Stein's Radburn 1929 plan that used crescents (loops) instead of cul-de-sacs was built in 1947: Wildwood Park, Winnipeg, designed by Hubert Bird.

In 1954, the Central Mortgage and Housing Corporation published its own guidelines[16] in which the cul-de-sac was strongly recommended for local streets and, as the FHA in the US, used its lending power to see its inclusion in development plans.

Although dead end streets would fit his definition of looped local roads, Alexander suggestions that "cul-de-sacs [sic] are very bad from a social standpoint—they force interaction and they feel claustrophobic, because there is only one entrance".

Whole neighbourhood street reconfigurations emerged in several cities, mainly concentrated in North America and the UK, which include Berkeley, California; Seattle, Washington; and Vancouver, British Columbia.

The transformation of grid plans since the 1970s limits access to an existing road that is newly designated as a major artery, enabling traffic to move smoothly on it, alleviating residents' concerns.

Since the end of World War II,[19] new subdivisions in the United States and Canada, as well as New Towns in England and other countries have made extensive use of the cul-de-sac and crescent (loops) street types.

In such earlier urban development, alleys were included to allow for deliveries of soiled supplies, such as coal, to the rear of houses, which are now heated by electricity, piped natural gas or oil.

The inverse correlation between amounts of traffic and sociability of streets was reconfirmed by a newer study[28] that repeated Appleyard's San Francisco analysis in Bristol, UK.

When cul-de-sacs are interconnected with foot and bike paths, as for example in Vauban, Freiburg and Village Homes in Davis, California, they can increase active modes of mobility among their residents.

[29] Real estate developers prefer cul-de-sacs 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.

From an environmental perspective, cul-de-sacs allow greater flexibility than the common grid in adapting to the natural grades of a site and to its ecologically sensitive features, such as streams, creeks, and mature forest growth.

[35] Related research in the United States by Richard Jackson has shown that people in car-based (cul-de-sac heavy) communities weigh on average 6 pounds (2.7 kg) more than those in traditional towns (with open grid networks).

Many contemporary lifestyle trends, some inevitable (sedentary work) and some avoidable (frequent energy-rich food consumption or the watching of television [four hours per day]), contribute to the imbalance and must be considered in understanding and combating obesity.

The impermeability deficiency of the typical cul-de-sac street can be addressed by applying a modified, improved version of it, mentioned above, that enables pedestrian and bicycle through-movement.

While this more permeable version can be applied in new developments easily, modifying existing impermeable cul-de-sac streets is problematic as it encounters property ownership issues.

Increases in pedestrian and bicycle permeability may result in a displacement of local car trips for short-distance destinations,[29] and consequently a reduction in neighbourhood vehicle emissions.

Results vary considerably among them, but there is general agreement on a number of key correlations:[37][38] a) the wealthier and the larger the family is, the more cars they own, and the more they drive, b) the farther away a family lives from the city centre, and the fewer the jobs in the vicinity, plus a slow bus service, the more they drive, and c) street patterns may add a 10% length to local trips, but the total VKTs are affected more by the "macro" urban than the "micro" neighbourhood structure.

Proponents of cul-de-sacs and gated communities have in turn countered that the reduction in through-traffic makes any "stranger" much more recognisable in the closed local environment and thus reduces crime danger.

A 2008 study[40] did extensive spatial analysis and correlated several building, site plan and social factors with crime frequencies and identified subtle nuances to the contrasting positions.

It concluded that the non-hierarchical, traditional layout generally shows lower peak speed and shorter, more frequent intersection delays than the hierarchical pattern.

Anecdotal and research evidence suggests that navigation (especially on foot) in a disconnected network of cul-de-sac and looped streets is inconvenient and non-intuitive, particularly when combined with curvilinear geometry.

More convincing about its workability for their permanent residents are the case histories of cities such as Regensburg that show a gradual transformation of an imported or imposed orthogonal, "legible" grid to the traditional "confusing" street networks.

Built examples of such connected cul-de-sacs can be found in the United States (such as Radburn, New Jersey, and Village Homes, California), England (such as Milton Keynes), and Greece (such as Papagou, a suburb of Athens).

The increased prevalence of cul-de-sac streets occurred in the 1960s and 1970s, a period of rapid economic and city expansion, when a detached house on a large lot meant an ideal form of habitation.

Weighing available evidence has led a few US cities including Austin, Texas; Charlotte, North Carolina; and Portland, Oregon, to restrict and regulate the inclusion of cul-de-sac streets in new suburbs.

The play and movies produced such a strong image of bleak futures and an unfair society that some municipalities changed the sign terminology for cul-de-sacs, often to "no outlet" or "no exit".