Assist Prof dr. Sabah Mohammed Abed Mosehab<br />Al MUSTAQBAL UNIVERSITY 1/4/024<br /> Building and Construction Techniques Engineering Department<br />Definition :<br />The compact city or city of short distances is an urban planning and urban design<br />concept, which promotes relatively high residential density with mixed land uses. <br />It is based on an efficient public transport system and has an urban layout which –<br />according to its advocates encourages walking and cycling , low energy consumption and <br />reduced pollution. A large resident population provides opportunities<br />for social interaction as well as a feeling of safety * in numbers and "eyes on the street". It is <br />also arguably a more sustainable urban settlement type than urban sprawl because it is <br />less dependent on the car, requiring less (and cheaper per capita ) infrastructure provision<br />The compact city model, ideally, creates benefits that are attractive to modern <br />urbanites . The desired benefits include shorter commute times (tiempos de viaje) , reduced <br />environmental impact of the community, and reduced consumption of fossil fuels and <br />energy. However, research on compact cities from around the globe suggests that these <br />outcomes are not guaranteed. To make matters worse, the design of the cities is limiting <br />residents’ access to green space and reasonable views. For the compact city model to gain in <br />popularity , it is necessary to review both their pros and cons <br />Why it Matters<br />Offsetting unavoidable CO2 emissions is a practical and immediate way of personal contribution to <br />climate change. Offsetting also reveals both the need for cleaner energy sources and opportunities for <br />reducing the carbon footprint<br />he term compact city was first coined in 1973 by George Dantzig and Thomas L. <br />Saaty, two mathematicians whose utopian vision was largely driven by a desire to see<br />more efficient use of resources. The concept, as it has influenced urban planning, is often <br />attributed to Jane Jacobs and her book The Death and Life of Great American Cities (1961), <br />a critique of modernist planning policies claimed by Jacobs to be destroying many existing <br />inner-city communities <br />Among other criticisms of the conventional planning and transport planning of the <br />time, Jacobs' work attacked the tendency, inherited ا from the garden city movement, towards <br />reducing the density of dwellings in urban areas. Four conditions were necessary to enable <br />the diversity essential for urban renewal : mixed uses, small walkable blocks, mingling <br />(mezclándo ) of building ages and types, and "a sufficiently dense concentration of people". The <br />'sufficient' density would vary according to local circumstances but, in general, a hundred <br />dwellings per acre فدان) 247 per hectare – high by American standards, but quite common in <br />European and Asian cities) could be considered a minimum <br />Important terms : <br />To understand a discussion about compact cities several key terms need to be <br />defined. The first term is urban density. Urban density refers to how many people live <br />in a square mile of land. It is used as a variable in evaluating how livable a city <br />design is . The optimal urban density for compact cities is high enough to keep <br />residents close to community amenities but low enough to allow residents <br />access to green spaces, reasonable privacy, and acceptable views . <br />Another term associated with the discussion about the compact city commuter<br />is self-sustaining. Self-sustaining means that the city has everything that a person <br />needs within the community . This includes stores, employers, a post office, <br />service providers, energy generation, waste disposal and processing, and <br />small-scale agricultural production (community gardens and/or vertical gardening).<br />Since the objective of the compact city is to make the community as accessible <br />as possible to residents, the term pedestrian design also needs to be defined.<br />Pedestrian design means that the compact city's layout and features ا support<br />pedestrian traffic . This is an important part of a compact city design because it <br />facilitates the flow of foot and bike traffic through the community. While a pedestrian <br />design will primarily focus on hardscape paisajismo elements , such as pathways and <br />sidewalks aceras , green space also is important to consider.<br />Green space, defined as the areas of nature found in the landscaping of a <br />community, includes grassy patches , flowerbeds, trees, rock gardens, and water <br />features. Green space is important in compact city designs because they enhance <br />the aesthetics of the community. It also helps to control storm runoff, and they help <br />to remove CO2 and other toxins from the air .<br />Proximity is the final term that needs to be defined. It refers to how close a <br />community's amenities are to where people live . Ideally, compact cities will keep <br />key amenities within walking distance of people's homes.<br />The acceptability of proximity to different amenities is calculated based on travel <br />time and distance<br />Compact cities and sustainability :<br />In the study by Rérat, the author discussed three criticisms of the compact city <br />model .<br />The first criticism was that supply and demand alignments are not feasible in <br />some cases. <br />What this means is that there are limits to how many people can fit into a space<br />because of resource and design limitations . <br />Additionally, while a high-density may be achievable, it likely will counter the <br />demands and expectations of residents who want more privacy and<br />more personal space.<br />The second criticism of the compact city is that to produce highly desirable <br />living conditions and a high quality of life, the cost of living needs to increase. <br />Consequently, integrating desirable traitscarecteris into compact cities makes the living <br />spaces expensive, pricing out lower-income families and pushing them <br />to the outskirts of town .<br />This stimulates urban sprawl and places the burden carga of longer commutes on <br />low-income workers, further expanding disparities disegua. in wealth and quality of life.<br />The third criticism of the compact city is that its environmental impacts are <br />significant. Dense populations mean waste and pollution are also dense. This <br />concentrates the impact of communities and necessitates expensive control<br />mechanism .<br />Rérat is not the only researcher showing evidence that compact cities are not as <br />sustainable as promised.. Wester nick . compared compact cities to dispersed <br />cities to see where sustainability factors differed. <br />The findings showed that compact cities excelled in efficient land<br />consumption, more flexible land use patterns, cost efficiency of development and <br />maintenance, and reduced reliance on fossil fuels and motor vehicles.<br />In contrast, however, the sustainability disadvantages included higher vulnerability<br />to disaster impacts , less personal space, less green space where people live, and <br />higher environmental impact because of density.<br />These drawbacks make compact cities less sustainable and justify the need for <br />design improvements<br />The compact city, urban sprawl and automobile dependency :<br />An influential study in 1989 by Peter Newman and Jeff Ken worthy compared <br />32 cities across North America, Australia, Europe and Asia .<br />The study's methodology has been criticized but the main finding that<br />( denser cities, particularly in Asia, have lower car use than sprawling cities, <br />particularly in North America, ) has been largely accepted .<br />sprawling city - a city spreading out wide area in a way that is not carefully planned.<br />Within cities, studies from across many countries (mainly in the developed world) <br />have shown that denser urban areas with greater mixture of land use and better public <br />transport tend to have lower car use than less dense suburban and exurban residential areas .<br />This does not necessarily imply that suburban sprawl causes high car use, however . <br />One confounding factor , which has been the subject of many studies, is Residential selfselection : People who prefer to drive tend to move towards low density suburbs, <br />whereas people who prefer to walk, cycle or use transit tend to move towards higher density<br />urban areas, better served by public transport<br />More recent studies using more sophisticated methodologies have generally refuted دحضت these <br />findings: Density, land use and public transport accessibility can influence travel behavior ;<br />although social and economic factors, particularly household income, usually exert a stronger<br />influence<br />The paradox of intensification :<br />Reviewing the evidence on urban intensification, smart growth ا and their <br />effects on travel behavior , Melia found support for the arguments of both <br />supporters and opponents of the compact city. Planning policies which increase <br />population densities in urban areas do tend to reduce car use, but the effect is a <br />weak one , so doubling the population density of a particular area will not halve the <br />frequency or distance of car use. <br />For example, Portland, Oregon, a U.S. city which has pursued smart growth policies, <br />substantially increased its population density between 1990 and 2000 when other US cities of a <br />similar size were reducing in density. As predicted by the paradox, traffic volumes and <br />congestion both increased more rapidly than in the other cities, despite a substantial <br />increase in transit use.<br />These findings led them to propose the paradox of intensification, which states :<br />Ceteris paribus, urban intensification which increases population density will reduce per <br />capita car use, with benefits to the global environment, but will also increase concentrations<br />of motor traffic, worsening the local environment in those locations where it occurs .<br />Conclusion :<br />Compact cities are designed to keep residents in close proximity to everything they <br />need for daily living , including shopping, education, housing, and work. The rationale of this <br />urban development model is to reduce the amount of time people spend commuting<br />desplazamientos as well as to reduce fossil fuel usage and to increase the sustainability of <br />developments. While compact cities promise short commutes viajes cortos and sustainable <br />designs, these benefits are not guaranteed . The problems preventing impiden the desired <br />outcomes include failure to consider the concentrated impact of dense populations on the <br />environment and lack of planning for green space and pollution control. If planning addresses <br />these issues and innovatesيبتكر to solve problems, everything promised by compact cities can be <br />delivered .<br />