Measuring Urban Design

Metrics for Livable Places

Reid Ewing, Otto Clemente

• Publisher: Island Press
• Year: 2013
• Print ISBN: 9781610911948, 9781610911931
• eBook ISBN: 9781610912099
• Topic: Architecture
• Subtopic: Architecture General

What makes strolling down a particular street enjoyable? The authors of Measuring Urban Design argue it's not an idle question. Inviting streets are the centerpiece of thriving, sustainable communities, but it can be difficult to pinpoint the precise design elements that make an area appealing. This accessible guide removes the mystery, providing clear methods to measure urban design.
 
In recent years, many "walking audit instruments" have been developed to measure qualities like building height, block length, and sidewalk width. But while easily quantifiable, these physical features do not fully capture the experience of walking down a street. In contrast, this book addresses broad perceptions of street environments. It provides operational definitions and measurement protocols of five intangible qualities of urban design, specifically imageability, visual enclosure, human scale, transparency, and complexity.
 
The result is a reliable field survey instrument grounded in constructs from architecture, urban design, and planning. Readers will also find a case study applying the instrument to 588 streets  in New York City, which shows that it can be used effectively to measure the built environment's impact on social, psychological, and physical well-being. Finally, readers will find illustrated, step-by-step instructions to use the instrument and a scoring sheet for easy calculation of urban design quality scores.
 
For the first time, researchers, designers, planners, and lay people have an empirically tested tool to measure those elusive qualities that make us want to take a stroll. Urban policymakers and planners as well as students in urban policy, design, and environmental health will find the tools and methods in Measuring Urban Design especially useful.

CHAPTER ONE

Introduction¹

In terms of the public realm, no element is more important than streets. This is where active travel to work, shop, eat out, and engage in other daily activities takes place, and where walking for exercise mostly occurs. Parks, plazas, trails, and other public places also have an important role in physical activity, but given the critical role and ubiquity of streets, this book focuses on the qualities that make one street more inviting and walkable than another. Think of your last trip to a great European city and what, other than the historic structures and the food, was memorable. You walked its streets for hours and did not tire. It is the magic of a great street environment.

Until recently, the measures used to characterize the built environment have been mostly gross qualities such as neighborhood density and street connectivity (see reviews by Ewing and Cervero 2010; Handy 2005; and Ewing 2005). The urban design literature points to subtler qualities that may influence choices about active travel and active leisure time. Referred to as perceptual qualities of the urban environment, or urban design qualities, such qualities are presumed to intervene between physical features and behavior, encouraging people to walk (see figure 1.1). Testing this presumption requires reliable methods of measuring urban design qualities, allowing comparison of these qualities to walking behavior.

Many tools for measuring the quality of the walking environment have emerged in the past few years. Generically called walking audit instruments, these are now used across the United States by researchers, local governments, and community groups. Robert Wood Johnson’s Active Living Research (ALR) website alone hosts sixteen walking audit instruments. They involve the measurement of such physical features as building height, block length, and street and sidewalk width.

Figure 1.1.

Urban design qualities are more than the individual physical features that they comprise, as they have a cumulative effect that is greater than the sum of the parts. Physical features individually may not tell us much about the experience of walking down a particular street. Specifically, they do not capture people’s overall perceptions of the street environment, perceptions that may have complex or subtle relationships to physical features.

Perceptual qualities are also different from such qualities as sense of comfort, sense of safety, and level of interest, which reflect how an individual reacts to a place—how a person assesses the conditions there, given his or her own attitudes and preferences. Perceptions are just that—perceptions. They may elicit different reactions in different people. They can be assessed objectively by outside observers; individual reactions cannot.

Our challenge in creating a tool to measure urban design qualities was to move from highly subjective definitions to operational definitions that capture the essence of each quality and can be measured reliably across raters, including those without training in urban design.

Why You Should Read This Book

Measuring Urban Design provides operational definitions and measurement protocols for five intangible qualities of urban design: imageability, visual enclosure, human scale, transparency, and complexity. To help disseminate these measures, this book also provides a field survey instrument that has been tested and refined for use by lay observers.

This instrument has several strengths. First, it is grounded conceptually in constructs from architecture, urban design, and planning. Second, it has been carefully tested and validated. Third, it comes with detailed instructions for assessing the five urban design qualities. For these reasons, the instrument offers researchers a “gold standard” for the systematic measurement of urban design. A test in New York City showed that the instrument can be implemented in large-scale studies relating the built environment to social, psychological, and health outcomes.

Initial Screening of Qualities

Key perceptual qualities of the urban environment were identified based on a review of the classic urban design literature. Without much empirical evidence, these qualities are presumed to influence people’s decisions to walk rather than drive to a destination, stroll in their leisure time, or just hang out and socialize on a street. Perceptual qualities figure prominently in such classics as those listed in box 1.1.

The research team also reviewed the visual preference and assessment literatures, which attempt to measure how individuals perceive their environments and to better understand what individuals value in their environments. Partial listing of this voluminous empirical literature is provided in Ewing (2000) and updated in Ewing et al. (2005). These literature reviews go beyond the boundaries of urban design to the fields of architecture, landscape architecture, park planning, and environmental psychology, as perceptual qualities of the environment figure prominently in these fields as well.

Our review yielded a list of fifty-one perceptual qualities of the urban environment (box 1.2). Of these fifty-one qualities, eight were selected for further study based on the importance assigned to them in the literature: imageability, enclosure, human scale, transparency, complexity, coherence, legibility, and linkage. Of the eight, the first five were successfully measured in a manner that passed tests of validity and reliability.

Box 1.1.

Classic Works in Urban Design That Address Perceptual Qualities

City Planning according to Artistic Principles, Camillo Sitte, 1889 (complete English translation 1986)

The Image of the City, Kevin Lynch, 1960

The Concise Townscape, Gordon Cullen, 1961

The Death and Life of Great American Cities, Jane Jacobs, 1961

A Pattern Language: Towns, Buildings, Construction, Christopher Alexander, Sara Ishikawa, and Murray Silverstein, 1977

Fundamentals of Urban Design, Richard Hedman, 1984

Finding Lost Space: Theories of Urban Design, Roger Trancik, 1986

Life between Buildings: Using Public Space, Jan Gehl, 1987

City: Rediscovering the Center, William Whyte, 1988

Town Planning in Practice, Raymond Unwin, 1909

History and Precedent in Environmental Design, Amos Rapoport, 1990

Great Streets, Allan Jacobs, 1993

Trees in Urban Design, Henry Arnold, 1993

Box 1.2.

Fifty-One Perceptual Qualities of the Built Environment

adaptability

distinctiveness

intricacy

richness

ambiguity

diversity

legibility

sensuousness

centrality

dominance

linkage

singularity

clarity

enclosure

meaning

spaciousness

coherence

expectancy

mystery

territoriality

comfort

focality

naturalness

texture

compatibility

formality

novelty

transparency

complementarity

human scale

openness

unity

complexity

identifiability

ornateness

upkeep

continuity

imageability

prospect

variety

contrast

intelligibility

refuge

visibility

deflection

interest

regularity

vividness

depth

intimacy

rhythm

Imageability

Imageability is the quality of a place that makes it distinct, recognizable, and memorable. A place has high imageability when specific physical elements and their arrangement capture attention, evoke feelings, and create a lasting impression. It is probably not one element by itself that makes a street imageable but rather the combination of many.

According to Kevin Lynch (1960), a highly imageable city is well formed, contains distinct parts, and is instantly recognizable to anyone who has visited or lived there. It plays to the innate human ability to see and remember patterns. It is a city whose elements are easily identifiable and grouped into an overall pattern.

Landmarks are a component of imageability. The term landmark does not necessarily denote a grandiose civic structure or even a large object. In the words of Lynch, it can be “a doorknob or a dome.” What is essential is its singularity and location, in relationship to its context and the city at large. Landmarks are a principle of urban design because they act as visual termination points, orientation points, and points of contrast in an urban setting. Tunnard and Pushkarev (1963, p. 140) attribute even greater importance to landmarks, saying, “A landmark lifts a considerable area around itself out of anonymity, giving it identity and visual structure.”

Figures 1.2a, b, c. Video clips shot at Fisherman’s Wharf, San Francisco, CA, rating high in Imageability.

Imageability is related to “sense of place.” Gorden Cullen (1961, p. 152) asserts that a characteristic visual theme will contribute to a cohesive sense of place and will inspire people to enter and rest in the space. Jan Gehl (1987, p. 183) explains this phenomena using the example of famous Italian city squares, where “life in the space, the climate, and the architectural quality support and complement each other to create an unforgettable total impression.” When all factors manage to work together to such pleasing ends, a feeling of physical and psychological well-being results: the feeling that a space is a thoroughly pleasant place in which to be.

Imageability is influenced by many other urban design qualities—enclosure, human scale, transparency, complexity, coherence, legibility, and linkage—and is in some sense the net effect of these qualities. Places that rate high on these qualities are likely to rate high on imageability as well—the neighborhoods of Paris or San Francisco, for example. However, places that rate low on these qualities may also evoke strong images, though ones that people may prefer to forget. Urban designers focus on the strength of positive images in discussing imageability and sense of place.

A panel of experts we assembled most often mentioned vernacular architecture as a contributor to imageability (Ewing and Handy 2009). Other influences mentioned were landmarks, striking views, unusual topography, and marquee signage. Beyond Kevin Lynch’s (1960) detailed qualitative characterizations, and two quantitative studies of building recall, we could find no attempts to operationalize imageability in either visual assessment studies or design guidelines.

Enclosure

Enclosure refers to the degree to which streets and other public spaces a...

Table of contents

• Cover
• Title Page
• Copyright
• Contents
• Acknowledgments
• Chapter one: Introduction
• Chapter two: Data Collection
• Chapter three: Analysis and Final Steps
• Chapter four: Urban Design Qualities for New York City
• Chapter five: Validation of Measures
• Chapter six: Field Manual
• Appendix 1: Biosketches of Expert Panel Members
• Appendix 2: Operational Definitions of Physical Features
• Appendix 3: Urban Design Qualities and Physical Features
• Appendix 4: Scoring Sheet Measuring Urban Design Qualities
• References