ゾーニング (都市計画)
ゾーニング (zoning) は、基礎自治体の領域内に線引きし、土地利用について一定の許可や禁止で条件づけながら、住宅地域、工業地域など、いくつかの区域 (zone) に分割していく過程である。
どの区域にあるかによって、そこにおける特定の開発行為に対して開発許可が下りるか否かが決まる。ゾーニングは、様々な形で、もっぱら特定の土地利用のみを認めることもあれば、土地利用に条件を付けていく場合もある。場合によっては、土地の面積や形状、さらに建物の形や大きさに条件を付けることもある。こうした指針は、都市の成長と発展を誘導する目的で設定される。
然るべき当局によって分割された土地では、区域によって様々な土地利用が許可される。このため、多くの先進諸国において、ゾーニングは、地方政府が都市計画の手段として、土地利用計画の技法を用いている。「ゾーニング (zoning)」という表現は、土地利用、形状、開発計画やその適合性などによって、地図上に区域/ゾーン (zone) を線引きしていく行為に由来している。法律上、ゾーニング計画は、然るべき手続きを経て条例として発効する。一般的なゾーイニング条例などは、その多くが子供たちが通う学校周囲に、大人向けの各商業施設(酒販売、ギャンブル、性的娯楽など)の設置を制限するものとして知られている。カナダやドイツなど、一部の国々においては、ゾーニング計画は、より上位の地方政府(地方、州など)による計画や政策に従わなければならない。
ゾーニングの類型には非常に大きな多様性があり、建物の形状や街路と建物の位置関係に規制に焦点を当てた形態規制条例と称されるものもあれば、土地利用の区分を重視する利用規制や、これらを折衷したものもある。同様に、特定の区域の利用目的を決めてしまうという都市計画上の手法も、古代以来数多くの都市で採用されてきた。
ゾーニングの主な目的は、互換性があると考えられる使用を分離することです。実際には、ゾーニングは、新しい開発が既存の用途に干渉するのを防ぎ、街の構造を維持するためにも使用されます。しかし、それを行うための効果的な方法であるとは限りません。 ゾーニングは一般的に都道府県や市区町村などの地方自治体によって管理されていますが、ゾーニング体制の性質は都道府県などによって決定または制限されるか、または法律を有効にすることによって決定される場合があります。オーストラリアでは、連邦政府の管理下にある土地は、州の計画管理の対象ではありません。米国と他の連邦諸国は似ています。フランスとドイツのゾーニングと都市計画は、国または連邦のコードによって規制されています。ドイツの場合、このコードにはゾーニング計画の内容と法的手続きが含まれます
ゾーニングには、特定のロット(オープンスペース、住宅、農業、商業、産業など)で許容される活動の種類、それらの活動を行うことができる密度(低密度住宅から)の規制が含まれる場合があります。高層マンションなどの高密度に一戸建て住宅など、建物の高さ、空間構造物の量、ロット上の建物の位置(挫折)、多くのスペースの種類の割合など美しいスペース、不浸透面、交通レーン、駐車場が提供されているかどうか。ドイツでは、ゾーニングには、非常に特定の緑地と補償規制を伴う影響評価が含まれており、建築設計に関する規制が含まれる場合があります。個々の計画システムが規制体制にゾーニングをどのように組み込むかの詳細は異なりますが、意図は常に似ています。たとえば、オーストラリアのビクトリア州では、土地利用区域は計画スキームオーバーレイのシステムと組み合わされ、任意の場所で望ましい都市の成果に影響を与える要因の多重性を考慮します。
ほとんどのゾーニング・システムには、問題のプロパティの特定の性質によって引き起こされるいくつかの認識された困難のために、差異(ゾーニング・ルールの例外)を付与する手順があります。
区域のゾーニングの起源は、古代にまで遡ることが出来る。古代の、城壁に囲まれた町は、用途に基いて土地を分類、規制する初期のものである。市壁の外は、つまり極めて貧しい人々が住んでいて、通常、騒音と臭いのために望ましくない作用があった。複数あった城壁と城壁の間のスペースは、精肉、廃棄物処理、レンガ焼きなどの、不衛生で危険な活動が行われた場所であった。 城壁の内側には大多数の人々が住んでいて、市民活動及び宗教の空間であった。
Beyond the simple distinction between urban and non-urban land, most ancient cities further classified land type and use inside their walls. That was practiced in many regions of the world. For example, in China during the Zhou Dynasty (1046 – 256 BC), in India during the Vedic Era (1500 – 500 BC), and in the military camps that spread throughout the Roman Empire (31 BC – 476 AD). As the residential districts made up the majority of the city, that early form of districting was usually along ethnic and occupational divides; generally, class or status diminished outwards from the city center. One legal form for enforcing it was the caste system.
While space was carved out for important public institutions, places of worship, markets and squares, there is a major distinction between cities of antiquity and cities of today. Throughout antiquity and up until the onset of the Industrial Revolution (1760 - 1840), most work took place within the home. Therefore, residential areas also functioned as places of labor, production, and commerce. The definition of home was tied to the definition of economy, which caused a much greater mixing of uses within the residential quarters of cities.
Throughout the Enlightenment and the Industrial Revolution, cultural and socio-economic shifts led to the rapid increase in the enforcement in and the invention of urban regulations. The shifts were informed by a new scientific rationality, the advent of mass production and complex manufacturing, and the subsequent onset of urbanization. Industry leaving the home was one major factor in reshaping industrial cities.
Overcrowding, pollution, and the urban squalor associated with factories were major concerns that led city officials and planners to consider the need for functional separation of uses. It was in France, Germany, and Britain that the first pseudo-zoning was invented to prevent polluting industries to be built in residential areas. It was Germany that invented modern zoning, in the late-19th century.
Basically, urban zones fall into one of five major categories: residential, mixed residential-commercial, commercial, industrial and spatial (e. g. power plants, sports complexes, airports, shopping malls etc.). Each category can have a number of sub-categories, for example, within the commercial category there may be separate zones for small-retail, large retail, office use, lodging and others, while industrial may be subdivided into heavy manufacturing, light assembly and warehouse uses. In Germany, each category has a designated limit for noise emissions (not part of the building code, but federal emissions code).
たとえば、米国またはカナダでは、住宅地域に次のサブカテゴリを含めることができる。
Residential occupancies containing sleeping units where the occupants are primarily transient in nature, including:  boarding houses, hotels, motels
Residential occupancies containing sleeping units or more than two dwelling units where the occupants are primarily permanent in nature, including: apartment houses, boarding houses, convents, dormitories.
Residential occupancies where the occupants are primarily permanent in nature and not classified as Group R-1, R-2, R-4 or I, including: buildings that do not contain more than two dwelling units, adult care facilities for five or fewer persons for less than 24 hours.
Residential occupancies where the buildings are arranged for occupancy as residential care/assisted living facilities including more than five but not more than 16 occupants.
Conditional zoning allows for increased flexibility and permits municipalities to respond to the unique features of a particular land use application. Uses which might be disallowed under current zoning, such as a school or a community center can be permitted via conditional use zoning.
Rothwell and Massey suggests homeowners and business interests are the two key players in density regulations that emerge from a political economy. They propose that in older states where rural jurisdictions are primarily composed of homeowners, it is the narrow interests of homeowners to block development because tax rates are lower in rural areas, and taxation is more likely to fall on the median homeowner. Business interests are unable to counteract the homeowners' interests in rural areas because business interests are weaker and business ownership is rarely controlled by people living outside the community. This translates into rural communities that have a tendency to resist development by using density regulations to make business opportunities less attractive.
Single-use zoning,  also known as Euclidean zoning, is a tool of urban planning that controls land uses in a city. The earliest forms of single-use zoning were practiced in New York city in the early 1900s, to guide its rapid population growth from immigration. Land uses were divided into residential, commercial and industrial areas, now referred to as zones or zoning districts in cities. Single-use zoning became known as Euclidean zoning because of a court case in Euclid, Ohio, which established its constitutionality, Village of Euclid, Ohio v. Ambler Realty Co. 272.
Euclidean zoning has been the dominant system of zoning in much of North America since its first implementation. The predictable model for dividing land use patterns generated by the Euclidean system have been charged by many commentators as playing a direct role in a number of problems in land use planning evident in the United States and elsewhere. Single-use zoning is a basic model that has not evolved to create appropriate solutions for the increasing complexity of social, political and environmental challenges in cities.
Problems affiliated with Euclidean-style zoning policy include urban sprawl, urban decay, environmental pollution, racial and socioeconomic segregation, negative economic impacts and an overall reduced quality of life. Land use regulations associated with a high separation of land uses have also been criticized as being fraught with legal obstacles to rehabilitating neighbourhoods affected by the aforementioned problems  (such efforts are often referred to as urban rehabilitation or urban renewal).
Euclidean zoning represents a functionalist way of thinking that uses mechanistic principles to conceive of the city as a fixed machine. This conception is in opposition to the view of the city as a continually evolving organism or living system, as first espoused by the German urbanist Hans Reichow.
Under the police power rights, state governments may exercise over private real property. With this power, special laws and regulations have long been made restricting the places where particular types of business can be carried on. In 1904, Los Angeles established the nation's first land-use restrictions for a portion of the city.  In 1916, New York City adopted the first zoning regulations to apply citywide as a reaction to The Equitable Building which towered over the neighboring residences, diminishing the availability of sunshine.  These laws set the pattern for zoning in the rest of the country. New York City went on to develop ever more complex regulations, including floor-area ratio regulations, air rights and others for specific neighborhoods.
The constitutionality of zoning ordinances was upheld by the U.S. Supreme Court in the 1926 case Village of Euclid, Ohio v. Ambler Realty Co. Among large populated cities in the United States, Houston is unique in having no zoning ordinances. Rather, land use is regulated by other means.
Early zoning practices were subtle and often debated. Some claim the practices started in the 1920s while others suggest the birth of zoning occurred in New York in 1916. Both of these examples for the start of zoning, however, were urban cases. Zoning becomes an increasing legal force as it continues to expand in its geographical range through its introduction in other urban centres and use in larger political and geographical boundaries. Regional zoning was the next step in increased geographical size of areas under zoning laws. A major difference between urban zoning and regional zoning was that "regional areas consequently seldom bear direct relationship to arbitrary political boundaries". This form of zoning also included rural areas which was counter-intuitive to the theory that zoning was a result of population density. Finally, zoning also expanded again but back to a political boundary again with state zoning.
Zoning codes have evolved over the years as urban planning theory has changed, legal constraints have fluctuated, and political priorities have shifted. The various approaches to zoning can be divided into four broad categories: Euclidean, Performance, Incentive, and form-based.
Named for the type of zoning code adopted in the town of Euclid, Ohio, and approved in a landmark decision of the U.S. Supreme Court, Village of Euclid v. Ambler Realty Co. Euclidean zoning codes are the most prevalent in the United States. Euclidean zoning is characterized by the segregation of land uses into specified geographic districts and dimensional standards stipulating limitations on development activity within each type of district. Advantages include relative effectiveness, ease of implementation, long-established legal precedent, and familiarity. However, Euclidean zoning has received criticism for its lack of flexibility and institutionalization of now-outdated planning theory.
Also known as "effects-based planning", performance zoning uses performance-based or goal-oriented criteria to establish review parameters for proposed development projects. Performance zoning is intended to provide flexibility, rationality, transparency and accountability, avoiding the arbitrariness of the Euclidean approach and better accommodating market principles and private property rights with environmental protection. Difficulties included a requirement for a high level of discretionary activity on the part of the supervising authority. Performance zoning has not been widely adopted in the USA.