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Urban density is a concept used in urban planning, urban studies, and related fields to describe the intensity of people, jobs, housing units, total floor area of buildings, or some other measure of human occupation, activity, and development across a defined unit of area. In general terms, urban density describes the degree of concentration or compactness of people or development in a city. [1] As such it is to be distinguished from other measures of population density. Urban density is considered an important factor in understanding how cities function. Research related to urban density occurs across diverse areas, including economics, health, innovation, psychology and geography as well as sustainability.
A 2019 meta-analysis of 180 studies on a vast number of economic outcomes of urban density concluded that urban density had net positive effects. However, there may be some regressive distributional effects. [2]
It is commonly asserted that higher-density cities are more sustainable than low-density cities. This is because they reduce urban sprawl, minimize land use, and make services and infrastructure more efficient and accessible to residents. [3] Much urban planning theory - particularly in North America, the UK, Australia, and New Zealand - has been developed premised on raising urban densities, such as New Urbanism, transit-oriented development, and smart growth. This assertion, however, remains a contested or challenged one. [4]
The link between urban density and aspects of sustainability remains a contested area of planning theory. [5] Jan Gehl, prominent Urban Designer and expert on sustainable urbanism, argues that low-density, dispersed cities are unsustainable as they are automobile dependent. NASA, for example, has established a direct correlation between urban density and air pollution. [6]
Others, such as Randal O'Toole of the libertarian Cato Institute, point to how raising densities results in more expensive real estate, greater road congestion, and more localized air pollution.[ citation needed ] At a broader level, there is evidence to indicate a strong negative correlation between the total energy consumption of a city and its overall urban density, i.e. the lower the density, the more energy consumed. [7] The location and urban setting where densification processes occur therefore need to be considered for sustainable densification. [8]
Urban density is a very specific measurement of the population of an urbanized area, excluding non-urban land-uses. Non-urban uses include regional open space, agriculture and water-bodies.
There are a variety of other ways of measuring the density of urban areas:
A 2019 meta-analysis of 180 studies on a vast number of economic outcomes of urban density concluded that urban density had net positive effects. However, there may be some regressive distributional effects. [2]
A 2020 study concluded that urban density "boosts productivity and innovation, improves access to goods and services, reduces typical travel distances, encourages energy efficient construction and transport, and allows broader sharing of scarce urban amenities. However, density is also synonymous with crowding and makes living and moving in cities more costly." [11]
Smart growth is an urban planning and transportation theory that concentrates growth in compact walkable urban centers to avoid sprawl. It also advocates compact, transit-oriented, walkable, bicycle-friendly land use, including neighborhood schools, complete streets, and mixed-use development with a range of housing choices. The term "smart growth" is particularly used in North America. In Europe and particularly the UK, the terms "compact city", "urban densification" or "urban intensification" have often been used to describe similar concepts, which have influenced government planning policies in the UK, the Netherlands and several other European countries.
Population density is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms too. It is a key geographical term.
One of the major subfields of urban economics, economies of agglomeration, explains, in broad terms, how urban agglomeration occurs in locations where cost savings can naturally arise. This term is most often discussed in terms of economic firm productivity. However, agglomeration effects also explain some social phenomena, such as large proportions of the population being clustered in cities and major urban centers. Similar to economies of scale, the costs and benefits of agglomerating increase the larger the agglomerated urban cluster becomes. Several prominent examples of where agglomeration has brought together firms of a specific industry are: Silicon Valley and Los Angeles being hubs of technology and entertainment, respectively, in California, United States; and London, United Kingdom, being a hub of finance.
Urban ecology is the scientific study of the relation of living organisms with each other and their surroundings in an urban environment. An urban environment refers to environments dominated by high-density residential and commercial buildings, paved surfaces, and other urban-related factors that create a unique landscape. The goal of urban ecology is to achieve a balance between human culture and the natural environment.
Urban sprawl is defined as "the spreading of urban developments on undeveloped land near a more or less densely populated city". Urban sprawl has been described as the unrestricted growth in many urban areas of housing, commercial development, and roads over large expanses of land, with little concern for very dense urban planning. Sometimes the urban areas described as the most "sprawling" are the most densely populated. In addition to describing a special form of urbanization, the term also relates to the social and environmental consequences associated with this development. In modern times some suburban areas described as "sprawl" have less detached housing and higher density than the nearby core city. Medieval suburbs suffered from the loss of protection of city walls, before the advent of industrial warfare. Modern disadvantages and costs include increased travel time, transport costs, pollution, and destruction of the countryside. The revenue for building and maintaining urban infrastructure in these areas are gained mostly through property and sales taxes. Most jobs in the US are now located in suburbs generating much of the revenue, although a lack of growth will require higher tax rates.
Sustainable transport refers to ways of transportation that are sustainable in terms of their social and environmental impacts. Components for evaluating sustainability include the particular vehicles used for road, water or air transport; the source of energy; and the infrastructure used to accommodate the transport. Transport operations and logistics as well as transit-oriented development are also involved in evaluation. Transportation sustainability is largely being measured by transportation system effectiveness and efficiency as well as the environmental and climate impacts of the system. Transport systems have significant impacts on the environment, accounting for between 20% and 25% of world energy consumption and carbon dioxide emissions. The majority of the emissions, almost 97%, came from direct burning of fossil fuels. In 2019, about 95% of the fuel came from fossil sources. The main source of greenhouse gas emissions in the European Union is transportation. In 2019 it contributes to about 31% of global emissions and 24% of emissions in the EU. In addition, up to the COVID-19 pandemic, emissions have only increased in this one sector. Greenhouse gas emissions from transport are increasing at a faster rate than any other energy using sector. Road transport is also a major contributor to local air pollution and smog.
Peter William Geoffrey Newman is an environmental scientist, author and educator based in Perth, Western Australia. He is currently Professor of Sustainability at Curtin University. He is best known for his contributions to the development of Perth's electrified metropolitan rail network through both activist and official consulting roles since the 1980s.
A sustainable city, eco-city, or green city is a city designed with consideration for the social, economic, and environmental impact, as well as a resilient habitat for existing populations. This is done in a way that does not compromise the ability of future generations to experience the same. The UN Sustainable Development Goal 11 defines sustainable cities as those that are dedicated to achieving green sustainability, social sustainability and economic sustainability. In accordance with the UN Sustainable Development Goal 11, a sustainable city is defined as one that is dedicated to achieving green, social, and economic sustainability. They are committed to this objective by facilitating opportunities for all through a design that prioritizes inclusivity as well as maintaining a sustainable economic growth. Furthermore, the objective is to minimize the inputs of energy, water, and food, and to drastically reduce waste, as well as the outputs of heat, air pollution. Richard Register, a visual artist, first coined the term ecocity in his 1987 book Ecocity Berkeley: Building Cities for a Healthy Future, where he offers innovative city planning solutions that would work anywhere. Other leading figures who envisioned sustainable cities are architect Paul F Downton, who later founded the company Ecopolis Pty Ltd, as well as authors Timothy Beatley and Steffen Lehmann, who have written extensively on the subject. The field of industrial ecology is sometimes used in planning these cities.
Car dependency is a phenomenon in urban planning wherein existing and planned infrastructure prioritizes the use of automobiles over other modes of transportation, such as public transit, bicycles, and walking.
The EcoDensity Initiative was officially launched in 2006 in Vancouver, British Columbia, Canada, in conjunction with the World Urban Forum. The initiative was a response to deconcentration of urban land use due to urban sprawl. The initiative used density, design and land use as catalysts towards livability, affordability and environmental sustainability. Some of the program's objectives were to reduce car reliance, deliver more efficient urban land use, improve green energy systems and build a resilient and adaptable community. In high-density urban areas, utilizing the existing infrastructure and transit and community amenities tends to lead towards a more sustainable and livable state. Accordingly, EcoDensity was designed to strategically enhance densification with the primary aim of efficiently structured neighbourhoods, denser urban-patterns and increased affordable housing.
In urban planning, walkability is the accessibility of amenities by foot. It is based on the idea that urban spaces should be more than just transport corridors designed for maximum vehicle throughput. Instead, it should be relatively complete livable spaces that serve a variety of uses, users, and transportation modes and reduce the need for cars for travel.
There are multiple environmental issues in India. Air pollution, water pollution, garbage, domestically prohibited goods and pollution of the natural environment are all challenges for India. Nature is also causing some drastic effects on India. The situation was worse between 1947 through 1995. According to data collected and environmental assessments studied by World Bank experts, between 1995 through 2010, India has made some of the fastest progress in addressing its environmental issues and improving its environmental quality in the world. However, pollution still remains a major challenge and opportunity for the country.
Land recycling is the reuse of abandoned, vacant, or underused properties for redevelopment or repurposing.
The compact city or city of short distances is an urban planning and urban design concept, which promotes relatively high residential density with mixed land uses. It is based on an efficient public transport system and has an urban layout which – according to its advocates – encourages walking and cycling, low energy consumption and reduced pollution. A large resident population provides opportunities for social interaction as well as a feeling of safety in numbers and "eyes on the street". It is also arguably a more sustainable urban settlement type than urban sprawl because it is less dependent on the car, requiring less infrastructure provision.
The sustainable urban neighbourhood (SUN) is an urban design model which is part of 21st-century urban reform theory, moving away from the typical suburban development of the UK and US towards more continental city styles. It emerged in the UK in the 1990s, specifically from pioneering work by URBED, an urban regeneration consultancy and research centre in Manchester.
Green urbanism has been defined as the practice of creating communities beneficial to humans and the environment. According to Timothy Beatley, it is an attempt to shape more sustainable places, communities and lifestyles, and consume less of the world's resources. Urban areas are able to lay the groundwork of how environmentally integrated and sustainable city planning can both provide and improve environmental benefits on the local, national, and international levels. Green urbanism is interdisciplinary, combining the collaboration of landscape architects, engineers, urban planners, ecologists, transport planners, physicists, psychologists, sociologists, economists and other specialists in addition to architects and urban designers.
Sustainable urbanism is both the study of cities and the practices to build them (urbanism), that focuses on promoting their long term viability by reducing consumption, waste and harmful impacts on people and place while enhancing the overall well-being of both people and place. Well-being includes the physical, ecological, economic, social, health and equity factors, among others, that comprise cities and their populations. In the context of contemporary urbanism, the term cities refers to several scales of human settlements from towns to cities, metropolises and mega-city regions that includes their peripheries / suburbs / exurbs. Sustainability is a key component to professional practice in urban planning and urban design along with its related disciplines landscape architecture, architecture, and civil and environmental engineering. Green urbanism and ecological urbanism are other common terms that are similar to sustainable urbanism, however they can be construed as focusing more on the natural environment and ecosystems and less on economic and social aspects. Also related to sustainable urbanism are the practices of land development called Sustainable development, which is the process of physically constructing sustainable buildings, as well as the practices of urban planning called smart growth or growth management, which denote the processes of planning, designing, and building urban settlements that are more sustainable than if they were not planned according to sustainability criteria and principles.
The externalities of automobiles, similar to other economic externalities, represent the measurable costs imposed on those who do not own the vehicle, in contrast to the costs borne by the vehicle owner. These externalities include factors such as air pollution, noise, traffic congestion, and road maintenance costs, which affect the broader community and environment. Additionally, these externalities contribute to social injustice, as disadvantaged communities often bear a disproportionate share of these negative impacts. According to Harvard University, the main externalities of driving are local and global pollution, oil dependence, traffic congestion and traffic collisions; while according to a meta-study conducted by the Delft University these externalities are congestion and scarcity costs, accident costs, air pollution costs, noise costs, climate change costs, costs for nature and landscape, costs for water pollution, costs for soil pollution and costs of energy dependency.
Climate change and cities are deeply connected. Cities are one of the greatest contributors and likely best opportunities for addressing climate change. Cities are also one of the most vulnerable parts of the human society to the effects of climate change, and likely one of the most important solutions for reducing the environmental impact of humans. The UN projects that 68% of the world population will live in urban areas by 2050. In the year 2016, 31 mega-cities reported having at least 10 million in their population, 8 of which surpassed 20 million people. However, secondary cities - small to medium size cities are rapidly increasing in number and are some of the fastest growing urbanizing areas in the world further contributing to climate change impacts. Cities have a significant influence on construction and transportation—two of the key contributors to global warming emissions. Moreover, because of processes that create climate conflict and climate refugees, city areas are expected to grow during the next several decades, stressing infrastructure and concentrating more impoverished peoples in cities.
Population-weighted density is the mean of the densities of subareas of a larger area weighted by the populations of those subareas.
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