A street hierarchy is a system of urban design that completely separates through automobile traffic from developed areas. Since the 1960s, it has been the dominant spatial arrangement of suburbs and exurbs in the United States, Canada, and Australia. It is also increasingly popular in Latin America, Western Europe, the United Kingdom, and China. Urban design is related to urban planning, but focuses on the physical design of places and deals at a more fine-grained scale. ... It has been suggested that Suburbia be merged into this article or section. ... The expression exurb (for extra-urban) was coined in the 1950s, by Auguste Comte Spectorsky in his book The Exurbanites, to describe the ring of prosperous rural communities beyond the suburbs that, due to availability via the new high-speed limited-access highways, were becoming dormitory communities for an urban... Latin America consists of the countries of South America and some of North America (including Central America and some the islands of the Caribbean) whose inhabitants mostly speak Romance languages, although Native American languages are also spoken. ... Western Europe is distinguished from Eastern Europe by differences of history and culture rather than by geography. ...

Description

Whereas arterial roads in a traditional grid plan are connected by dozens of through streets, the street hierarchy completely eliminates all straight-line connections between arterials. In its place, a series of cul-de-sacs feed into a primary or secondary "collector" (either a ring road or a long, curvilinear "front-to-back" path) that in turn feeds the arterial. Large subdivisions often have three- or even four-tiered hierarchies, feeding into one or two massive collectors that are often as wide as the Champs-Elysees or Wilshire Boulevard. Arterials in this arrangement are rarely less than four lanes in width, and in large contemporary suburbs such as Naperville, Illinois or Irvine, California are often eight or even ten lanes wide. Adjacent street hierarchies are sometimes connected to one another, but this is generally quite rare. An arterial road is a high-capacity road which is just below a highway level of service. ... The grid plan is a type of city plan in which streets run at right angles to each other, forming a grid. ... For the musical group, see Cul de Sac (group). ... Avenue des Champs- es from Place de la Concorde Looking east along the Champs- es from the top of the Arc de Triomphe The Champs- es (pronounced /ʃɑ̃zelize/, IPA; /SA~ ze. ... Wilshire Boulevard is the principal east-west surface street in Los Angeles, California. ... Naperville is a city located in DuPage County, Illinois and Will County, Illinois, USA. As of the 2000 census, the city had a total population of 128,358; a special census in 2003 estimated the population at 135,858. ... Location Location of Irvine within Orange County, California. ...

History

The street hierarchy has its roots in the concerns of early urban planners in the 1920s, who saw a threat to small children from the automobile. Their chief priority was in making it safe for primary school-age children to walk to school. Originally, planners tweaked the grid into a "superblock" system, where high traffic generators such as shops and apartments were banished to the arterial roads that formed the boundaries of the superblock. Within the block, traffic calming measures would discourage through traffic, and community institutions such as schools, churches, and parks were concentrated at the center. This model prevailed between roughly 1930 and 1955 in "instant cities" such as Lakewood, California and the Los Angeles district of Panorama City. However, the street hierarchy has dominated the landscape of new suburbs from the Levittowns onward. Paris, France: One of the worlds great cities that began unplanned, but was later re-enginnered through the construction of an extensive system of wide boulevards overlaid on the medieval street grid, by the Baron Haussman under the reign of Napoleon III in the 19th century. ... Primary or elementary education is the first years of formal, structured education that occurs during childhood. ... A traffic calming measure in Germany: street narrowing Traffic calming is a set of strategies used by urban planners and traffic engineers which aims to slow down traffic and improve safety for pedestrians and bicyclists, although some of these features can also be dangerous to cyclists. ... Lakewood is a city located in Los Angeles County, California. ... Panorama City is a neighborhood in the San Fernando Valley district of Los Angeles, California. ... Levittown is the name of some places in the United States of America: Levittown, New York Levittown, Pennsylvania There is also a Levittown, Puerto Rico, and there was, for a time, a Levittown, New Jersey, but the latter has reverted to its previous name of Willingboro Township, New Jersey. ...

In the 1960s heyday of operations research and rational planning, the street hierarchy was seen as a major improvement over the "messy" grid system, which has limited facility for preventing through traffic. It also prevented drag racing and other forms of dangerous high-speed automobile travel from occuring in residential areas. As a result, new "master-planned" suburbs often codified the street hierarchy into their zoning laws, banning grids from all residential areas. Eventually, the street hierarchy was also adapted to use in industrial parks and commercial developments. In the latter, use of the street hierarchy is a nearly universal characteristic of the "edge city," a roughly post-1970 form of urban development exemplified by places such as Tysons Corner, Virginia and Schaumburg, Illinois. Operations research, operational research, or simply OR, is the use of mathematical models, statistics and algorithms to aid in decision-making. ... Jump to: navigation, search Drag racing is a form of auto racing in which cars or motorcycles attempt to complete a fairly short, straight and level course in the shortest amount of time, starting from a dead stop. ... In general, zoning is the division of an area into sub-areas, called zones. ... An industrial park is an area of land set aside for industrial development. ... Edge city is an American term for a relatively new concentration of business, shopping and entertainment outside a traditional urban area, in what had recently been a residential suburb or semi-rural community. ... Tysons Corner is an unincorporated place located in Fairfax County, Virginia, near Washington, DC. Recognized by the U.S. Census Bureau as a census-designated place, the community had a total population of 18,540 as of the 2000 census. ... Schaumburg is a village located in Cook County and DuPage County, Illinois. ...

Criticisms

Social commentators and urban planners have often pointed out that the street hierarchy arrangement has serious limitations. These criticisms are generally part of a broader indictment of mid-20th-century urban planning, with critics charging that planners have only considered the needs of young children and their working-age parents in creating the spatial arrangement of the late 20th and early 21st centuries.

New Urbanists decry the street hierarchy's deleterious effects on pedestrian travel, which is made easy and pleasant within the subdivision but is virtually impossible outside it. Residential subdivisions usually have no pedestrian connections between themselves and adjacent commercial areas, and are often separated from them by high masonry walls intended to block noise. New Urbanist writers like Andres Duany and James Howard Kunstler often point out the absurd nature of car trips forced by the street hierarchy: while a grocery store may be less than a quarter-mile distant "as the crow flies" from a given home in a subdivision, the barriers to pedestrian travel presented by the street hierarchy mean that getting a gallon of milk requires a car trip of a mile or more in each direction. Jane Jacobs, among other commentators, has gone so far as to say that modern suburban design--of which the street hierarchy is the key component--is a major factor in today's childhood obesity epidemic.[1] Houses in Kentlands, Maryland, an early new urbanist neighborhood. ... Andr s Duany (born September 7, 1949) is a American architect and urban planner. ... --- James Howard Kunstler (born 1948) is an American author and social critic. ... Jane Jacobs Jane Jacobs (born on May 4, 1916) is a U.S.-born, but Canada-based writer and activist. ...

Mass transit advocates contend that the street hierarchy's denigration of pedestrian traffic also reduces the viability of public transportation in areas where it prevails, sharply curtailing the mobility of those who do not own cars or cannot drive them, such as teeangers and the elderly. In the United States of America, transit describes local area common carrier passenger transportation configured to provide scheduled service on fixed routes on a non-reservation basis. ...

While most traffic engineers consider the street hierarchy to be optimal, since it eliminates through traffic on all streets except arterials, a small number consider the street hierarchy to be financially wasteful, since it requires far more miles of street to be laid than a grid plan. Additionally, since especially large subdivisions often have hundreds of cars entering or exiting them at rush hour periods, the restriction of automobile traffic to a single collector-arterial intersection can create choke points that lead to significant traffic congestion. In edge cities, these numbers can be multiplied by a factor of ten or even one hundred, leading to miles-long queues to get on freeway ramps nearby. The term traffic engineering is used in more than one sense. ... The grid plan is a type of city plan in which streets run at right angles to each other, forming a grid. ... Rush hour in a city A rush hour is a part of the day with busy traffic and hence traffic congestion on the roads and crowded public transport; normally the two periods in a day when people are travelling to or from work or school. ... In geography terms it is a narrowing of an international waterway to a distance of less than 24 miles (38 km), necessitating the drawing of a median line (maritime) boundary. ... Traffic jams are common in heavily populated areas. ... High-capacity freeway interchange in Los Angeles, California. ...

Future prospects

While street hierarchies remain the default mode of suburban design in the United States, it is likely that they will become less popular in the 21st century. As developable land becomes scarce in coastal urban areas and in geographically constrained inland cities such as Tucson, Las Vegas, and Salt Lake City, the street hierarchy's inability to handle any but the lowest population densities is a long-term liability. (Indeed, real estate developers in areas with high land prices, such as Southern California's Inland Empire, are finding that the relatively high population density of contemporary subdivisions is leading to severe traffic congestion on arterial roads that were country lanes a decade earlier.) The street hierarchy is also becoming less attractive as awareness increases of the environmental consequences of the urban planning paradigm of which it is an integral part. Most "smart growth" advocates call for a return to the traditional grid, and with it the supremacy of the pedestrian. In increasingly automobile-obsessed countries such as Brazil and China, however, it is likely that the street hierarchy will become increasingly prevalent as the century progresses. Tucson (pronounced ) is a city and the county seat of Pima County, Arizona, located 135 miles (217 km) southeast of Phoenix. ... Welcome to Fabulous Las Vegas sign just to the south of the Las Vegas Strip welcoming visitors to the city City nickname: The Entertainment Capital of the World Location Location of Las Vegas in Nevada Government County Clark Mayor Oscar B. Goodman Physical characteristics Area      Land      Water 293. ... ... The Inland Empire, shaded in red (the boundary is approximate) For residents of Southern California, the Inland Empire is a popular informal name for a region located at the eastern end of the Los Angeles Metropolitan Area. ... Smart growth development policies aim to prevent urban sprawl and pollution, and reduce the profligate use of non-renewable fuels, particularly an excessive dependency on private cars in industrialised countries. ...

References

• Hise, Gregory (1997). Magnetic Los Angeles: Planning the Twentieth-Century Metropolis. Baltimore: Johns Hopkins University Press. ISBN 0-8018-6522-8.
• Kunstler, James Howard (1993). The Geography of Nowhere: The Rise and Decline of America's Man-Made Landscape. New York: Simon and Schuster. ISBN 0-6717-0774-4.
• Nivola, Pietro (1999). Laws of the Landscape: How Policies Shape Cities in Europe and America. Washington: Brookings Institution Press. ISBN 0-8157-6081-7.