Definition of Urban Design
Throughout this report, we will refer to "good urban design," but there is no universal acceptance of what this means. Development patterns are often classified according to the "three D's," which are density, diversity, and design (Cervero and Kockelman). Two additional D's--destination accessibility and distance to transit--have also been suggested (Ewing et al). Well-planned, walkable communities have all of these characteristics – adequate levels of density, a diversity of land uses, well-designed streetscapes and buildings, clear destinations for the pedestrian, and proximity to transit.
Reid Ewing, a research professor at the National Center for Smart Growth at the University of Maryland, has researched how urban design affects human perception and behavior in well-designed places, and has developed some of the best definitions of good urban design. His research argues that good urban design shows
- Imageability the quality of a place that makes it distinct, recognizable, and memorable.
- Legibility visual cues that allow pedestrians and motorists alike to navigate the environment with ease
- Enclosure the degree to which streets and other public spaces are visually defined by buildings, walls, trees, and other elements.
- Human Scale size, texture, and articulation of physical elements that match the size and proportions of humans
- transparency the degree to which people can see or perceive what lies beyond the edge of a street or other public space.
- Linkage the continuity of the form between buildings and streets specifically the sidewalks and crosswalks that lead you from one place to another
- Complexity the condition and cleanliness of a place.
- Coherence complimentary visual elements, all the buildings are similar in size and style
- Tidiness nothing looks damaged or is in need of repair, no eyesores
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Included in these terms are many concepts like the skyline buildings create, open vs. built-up areas, streetscape, building materials and color, street furniture and public art. Another commonly cited guide for good urban design is the Charter of the Congress for the New Urbanism.