Urban Density: An Oversimplified Concept?

Urban Density refers to the way people and buildings interact.

Urban density is a term used in  planning and  design to refer to the number of people inhabiting a given urbanized area. As such it is to be distinguished from other measures of population density. Understanding Urban density provides important insights of how cities function. Research related to urban density occurs across diverse areas, including economics, health, innovation, psychology and geography as well as sustainability

In debates about urban density, we often find comments about buildings being too tall or not tall enough, about too many people in a neighbourhood or too few, about streets and buildings being overcrowded or empty.

We are told that Melbourne is building at four times the density of Hong Kong. As these debates over density in Australian cities continue, what is most often missing is any clear understanding of what people mean when they use the word “density”.

Is it the volume or height of buildings? Or is it the numbers of people? One person’s high density may be another’s sprawl; the same tall building may be experienced as oppressive or exhilarating; a “good crowd” for one can be “overcrowded” for another.

We need to clarify whether we are talking about concentrations of people or of buildings. If we take population densities first, these are generally measured as residents per hectare based on census data.

But we also need to distinguish between “internal” and “external” densities – the numbers of people in a room or apartment versus those in an urban precinct. If one look at new high-rise housing in the evening, you can find many apartments unoccupied. At the other extreme, internal crowding largely defines a slum. Building density does not mean population density.

Population densities cannot be based on residents alone since the numbers of people in a given neighbourhood at a given time include those who work there or are visiting. In a mixed-use neighbourhood, residents may be a small proportion of the population density.

There is also the question of streetlife density – of people in public space, of crowds and crowding. Here the complexities multiply. While we can measure the outcomes in pedestrians per minute or per square metre, we are far from understanding the ways in which streetlife is geared to building and population densities.

Building orientation is also an important aspect. How the building interacts with the street. How the inflow and outflow of traffic from a railway station and bus station is also crucial.

Sustainability

It is often asserted that higher density cities are more sustainable than low density cities. 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. development, and Smart growth. This view suggest that high density is good for cities as it gives financial viability to city infrastructure.

However, the link between urban density and aspects of sustainability remains a contested area of planning theory. Jan Gehl, prominent Urban Designer and expert on sustainable urbanism, argues that low-density, dispersed cities are unsustainable as they are automobile dependent. A minority, such as Randy O’Toole of the Libertarian Cato Institute, counter that raising densities results in more expensive real estate, greater road congestion and more localized air pollution. Others counter that traffic congestion is a result not of population density but of parking capacity.[ 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.

Measurement

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:

  • Floor area ratio – the total floor area of buildings divided by land area of the lot upon which the buildings are built
  • Residential density – the number of dwelling units in any given area
  • Population density – the number of human persons in any given area
  • Employment density – the number of jobs in any given area
  • Gross density – any density figure for a given area of land that includes uses not necessarily directly relevant to the figure (usually roads and other transport infrastructure)
  • Net density – a density figure for a given area of land that excludes land not directly related to the figure.
  • Weighted density – a density metric which measures the density at which the average citizen lives. It is determined by calculating the standard density of each census tract, assigning each a weight equal to its share of the total population, and then adding the segments.

A small interesting video about urban density

Link(s) and Source(s):

Wikipedia

Citi Io

Smart City Dimensions

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A Colourful Morning in Aligarh

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Disaster Management: The Concept

The United Nations defines a disaster as a serious disruption of the functioning of a community or a society. Disasters involve widespread human, material, economic or environmental impacts, which exceed the ability of the affected community or society to cope using its own resources.

The Red Cross and Red Crescent societies define disaster management as the organisation and management of resources and responsibilities for dealing with all humanitarian aspects of emergencies, in particular preparedness, response and recovery in order to lessen the impact of disasters.

Types of Disasters

There is no country that is immune from disaster, though vulnerability to disaster varies. There are four main types of disaster.

  • Natural disasters: including floods, hurricanes, earthquakes and volcano eruptions that have immediate impacts on human health and secondary impacts causing further death and suffering from floods, landslides, fires, tsunamis.
  • Environmental emergencies: including technological or industrial accidents, usually involving the production, use or transportation of hazardous material, and occur where these materials are produced, used or transported, and forest fires caused by humans.
  • Complex emergencies: involving a break-down of authority, looting and attacks on strategic installations, including conflict situations and war.
  • Pandemic emergencies: involving a sudden onset of contagious disease that affects health, disrupts services and businesses, brings economic and social costs.

Any disaster can interrupt essential services, such as health care, electricity, water, sewage/garbage removal, transportation and communications. The interruption can seriously affect the health, social and economic networks of local communities and countries. Disasters have a major and long-lasting impact on people long after the immediate effect has been mitigated. Poorly planned relief activities can have a significant negative impact not only on the disaster victims but also on donors and relief agencies. So it is important that physical therapists join established programmes rather than attempting individual efforts.

Local, regional, national and international organisations are all involved in mounting a humanitarian response to disasters. Each will have a prepared disaster management plan. These plans cover prevention, preparedness, relief and recovery.

Prevention

These are activities designed to provide permanent protection from disasters. Not all disasters, particularly natural disasters, can be prevented, but the risk of loss of life and injury can be mitigated with good evacuation plans, environmental planning and design standards. In January 2005, 168 Governments adopted a 10-year global plan for natural disaster risk reduction called the Hyogo Framework. It offers guiding principles, priorities for action, and practical means for achieving disaster resilience for vulnerable communities.

Preparedness

These activities are designed to minimise loss of life and damage – for example by removing people and property from a threatened location and by facilitating timely and effective rescue, relief and rehabilitation. Preparedness is the main way of reducing the impact of disasters. Community-based preparedness and management should be a high priority in physical therapy practice management.

Relief

This is a coordinated multi-agency response to reduce the impact of a disaster and its long-term results. Relief activities include rescue, relocation, providing food and water, preventing disease and disability, repairing vital services such as telecommunications and transport, providing temporary shelter and emergency health care.

Recovery

Once emergency needs have been met and the initial crisis is over, the people affected and the communities that support them are still vulnerable. Recovery activities include rebuilding infrastructure, health care and rehabilitation. These should blend with development activities, such as building human resources for health and developing policies and practices to avoid similar situations in future.

Source(s):

read here

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A Crop-by-Crop Guide to Growing Organic Vegetables and Fruits

Agriculture Information Bank

Our comprehensive crop guides take you crop-by-crop through common vegetables and fruits for backyard gardeners. Each guide explains how to plant, when to plant, best harvest practices, how to save seeds, and how to deal with common pests and diseases naturally, setting you on your way to growing organic vegetables and fruits in your home garden successfully.

 

In each crop guide, you’ll also find a list of the different crop types to consider growing, plus a list of recommended varieties for each type. (Use our custom Seed and Plant Finder to locate seed companies that sell varieties you want to try.) If you’re curious about how to put a particular vegetable or fruit to good use in your cooking, check out the “In the Kitchen” section of each guide.

 

Written by expert gardener Barbara Pleasant, our “Crop at a Glance” collection teaches you how to grow everything from…

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