Cities are growing at unprecedented rates. Most continue to sprawl into the countryside. Some are only now adopting policies that attempt to control air pollution from vehicles, reduce water pollution from urban runoff, and repair fragmented urban ecosystems. Can good urban design and sound environmental design coincide at a neighborhood level to create healthy communities?
Absolutely, and the strategies presented by Cynthia Girling and Ronald Kellett in Skinny Streets and Green Neighborhoods illustrate how to weave together contemporary thinking in urban planning with open space planning and urban ecology. Drawing from eighteen case studies, these green neighborhoods are the best examples of how the natural environment can play integral roles in neighborhoods.
Green neighborhoods offer a mix of housing types in order to serve a broad cross-section of people with a finely-grained variety of land uses and services, all close to home. In ecologically sound communities, the urban landscape is a functioning part of the whole ecosystem. Wooded areas, meandering streams, wetlands, and open spaces are planned and engineered to clean the air and the water. Skinnier streets and practical pathways weave into a functional, economical network to provide a range of equally good transportation choices, from walking to mass transit, that move people efficiently and economically.
This book moves beyond identifying problems to demonstrate proven methods and models that solve multiple, complex problems in concert. With innovative ideas and practical advice, Skinny Streets and Green Neighborhoods is a guide for today's planners, architects, engineers, and developers to betterneighborhoods and a more natural metropolis.
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About the Author
Cynthia Girling is Director and Associate Professor of Landscape Architecture at the University of British Columbia and author of numerous publications and books including Yard, Street, Park: The Design of Suburban Open Space (John Wiley and Sons, 1994).
Ronald Kellett is an architect, Professor of Landscape Architecture, and Director of the Neighborhoods LAB in the Design Centre for Sustainability at the University of British Columbia.
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Skinny Streets and Green Neighborhoods
Design for Environment and Community
By Cynthia Girling, Ronald Kellett
ISLAND PRESSCopyright © 2005 Cynthia Girling and Ronald Kellett
All rights reserved.
Traditional building forms and settlement patterns are the product of dialogues among natural and cultural processes.
A.W. Spirn, "New Urbanism and the Environment"
Even very large cities grow in small increments. The term "neighborhood" is frequently used to describe the urban "building blocks" of complementary land uses, transportation networks, services, and amenities. These systems are typically conceived together to benefit from the identity and location afforded by being in the same "neighborhood" as well as to leverage the substantial investment of land, capital, infrastructure, and human will it takes to create them. Cliff Moughtin quotes Boyd: "A neighborhood is formed naturally from the daily occupations of people, the distance it is convenient ... to walk ... to daily shopping ... and a child to walk to school. He should not have a long walk and he should not have to cross a main traffic road. The planning of a neighborhood starts from that."
While "neighborhood" can be defined in diverse ways, the term is used in this book in a spatial sense of sharing common proximity and boundary. Understood this way, neighborhoods are those broadly legible, if not precisely definable, areas of cities in which people say they live, work, learn, or play. It is also the scale at which new areas of many cities are planned. Within this definition, neighborhoods may vary substantially in physical size, shape, population, density, or character. Several may link together to form a larger, interdependent group of neighborhoods. In contemporary usage, that proximity has frequently come to be defined as the distance that one can (or would be willing to) walk to services or to a transit stop (between five and ten minutes, or one-quarter to one-half mile for most people). That represents a land area of roughly 125 to 500 acres. Neighborhoods also have edges or boundaries that differentiate one from another. These edges can vary in type and character. Some may be hard and explicit (such as a wide, heavily trafficked street), whereas others may be soft and implicit (such as a contrasting land use or a common open space), allowing several neighborhoods to overlap or interconnect along a shared edge (Figure 1.1).
Taken together, domain and edge are the physical conditions of a neighborhood in planning and urban design. Nineteenth-century British urban theorist Ebenezer Howard and architects Raymond Unwin and Barry Parker, who gave physical form to Howard's theories, recognized the importance of these attributes of neighborhood. They shaped the Garden City, a new-town planning concept, around a "ward"—a district or quarter centered around the social institution of a school and separated from others by a greenbelt. The eleven British new towns authorized by the New Towns Act of 1946—for example, Runcorn and Ipswich—are defined by the following: a ten- to fifteen-minute walking distance from the farthest home to the school; a population that supports an elementary school and local services; a clearly defined boundary (typically reinforced by landscape); a center; through traffic relegated to perimeter streets; and an architectural treatment that distinguishes it from other neighborhoods.
In the United States, Clarence Perry's 1929 essay on the neighborhood unit borrowed many themes from Howard. Perry argued that a neighborhood should be approximately 160 acres and should support a density of ten households per acre. The resulting population would support an elementary school (located at a central focal point of community services) and commercial services (located along edges with other neighborhoods). Several smaller parks and recreation areas would make up 10 percent of the land area. Neighborhood shape should be such that all households were within walking distance (less than half a mile) of a school and services. Neighborhood boundaries should follow major streets to keep high-volume traffic at the edges, reducing traffic through the neighborhood. Residential streets interior to the neighborhood could be smaller, with less automobile traffic. Only a few should connect directly to larger boundary streets.
Perry's work eventually led to national neighborhood planning standards published in the industry-wide technical bulletins of the U.S. Federal Housing Administration. After World War II, qualification for federal mortgage assistance was directly tied to these standards; thus they explicitly influenced the development pattern of a generation of subdivisions throughout the United States in the 1950s and 1960s.
Perry's work and its antecedents have informed neighborhood planning and design practice for almost eighty years. From the planning and urban design work of Perry's contemporary Clarence Stein to the contemporary town-making principles of the Congress for the New Urbanism, planners, landscape architects, and architects have adapted and built upon his ideas and concepts (Figure 1.2). A comparison of Clarence Perry's 1929 principles of neighborhood planning with those of Duany and Plater Zyberk (1997) show extensive agreement. For both, the preferable size is a 160-acre area bounded by larger scale streets and developed at densities sufficient to support an elementary school. Exact shape is not essential but should fit within a quarter-mile (5-minute walk) circle such that all sides are roughly equidistant from the center.
1. Neighborhood institutions only at community center in the Perry version, Shops and institutions near a transit stop in the DPZ version.
2. Apartments and shopping districts at higher traffic intersections. Parking lots double as plazas in the DPZ version.
3. Narrow interior streets configured for easy access to shops and community center. A mixed use street is anchored by shopping districts in the DPZ version.
4. Civic buildings occupy prominent sites. A shopping district could substitute for a perimeter church site in the Perry version.
5. A school and related recreation spaces may be located near the edge where it can be shared with an adjacent neighborhood.
6. A playground is located in each quadrant.
7. Boulevard edges may develop with (a) the short faces of traditional blocks; (b) workshops and offices; (c) a parkway corridor.
8. Street and block patterns connect to adjacent neighborhoods to greatest extent possible.
To Clarence Perry's 1929 principles of the neighborhood unit, New Urbanists such as Duany and Plater-Zyberk have added several that address the urban design and architecture of neighborhoods. Still missing are principles that address environmental factors.
Defining Green Neighborhoods
Many attributes embedded in the spatial models of neighborhood mentioned above offer the opportunity to improve urban environmental quality. Principles of the new urbanism, for example, generate development patterns that use land more economically than does prevailing contemporary practice. Densities are sufficiently high and land uses sufficiently mixed to increase the likelihood that daily services (stores, recreation, and schools, for example) are within walking distance. Street networks are sufficiently connective to encourage fewer automobile trips (and thus improve air quality and energy conservation) through choice of mode. Streets that make up the network are typically skinny—they are scaled and designed for equity of use among cars, bicycles, and pedestrians. Walking or bicycling becomes a viable alternative to driving for travel within the neighborhood, and transit becomes a viable option for travel outside the neighborhood.
Less explicit and integral, however, are places for nature. More often, natural areas have limited or peripheral roles, typically as edges or boundaries to neighborhoods. Such roles increase the real and perceived barriers between natural and urban systems as well as weaken opportunities to integrate urban and natural functions. A more "green" model would create explicit places for nature and ecological functions, integrate them with the development pattern, and balance the competing spatial demands of open space, streets, and land uses within.
How might nature become more integral with urban development? For the sake of argument, assume that natural spaces are most often the open spaces of an urban pattern. Urban planner and observer Kevin Lynch has argued that open space is distributed in relatively few spatial patterns. In his lexicon, three patterns exist (Figure 1.4): the greenbelt (open space encloses urban development—an edge), the green wedge (open space radiates from a center), and the green network (a more broadly distributed but linked pattern of open space). These patterns represent contrasting points of view about open space and, by extension, about nature in cities. In one view, open spaces tend to be large and concentrated to give size, shape, and form to the built development pattern. In the other view, open spaces tend to be smaller, more dispersed, and more selectively contiguous to increase access to and interface with the built pattern.
The linked network pattern in particular abandons the convention of giving a hard form to open space pattern and focuses instead on a more negotiated distribution and connection of diverse open space elements. Open spaces and connections could be larger, and connections to them more generous, at points of higher environmental value and lesser development value, such as near an important stream corridor. Open spaces could be smaller, and connections to them narrower, at points of high development value and lower environmental value, such as near major roads. Since this open space pattern is continuous and interconnected yet closely intertwined with urban uses at many points, nature is more easily close at hand. From many points in developed areas, people can more easily connect to the open space system and, once in the system, can move through it uninterrupted.
Clarence Stein's neighborhood prototype is an example of a networked open space pattern (Figure 1.5). Stein's plan follows the convention of a school-centered service area of approximately a half-mile radius with emphasis on the amount and distribution of open space in a linear, interconnected pattern. Stein also significantly reduced land areas allocated to streets, purposefully decreased connectivity for automobiles, and increased connectivity and accessibility to commercial services for pedestrians and bicycles. This design, which fundamentally changed the development pattern from street centered to open space centered, became known as the Radburn pattern, after its best-known example in New Jersey (Figure 1.6). Despite the opportunity presented, Stein's prototype was never completed at Radburn; the small built portion did not realize potential open space connectivity at larger scales, from neighborhood to neighborhood or from neighborhood to natural areas.
More recently, architect Peter Calthorpe has made open space and resource protection a key guiding principle in his neighborhood prototype, the transit-oriented development (TOD). Advocating conservation of major creeks, riparian habitat, and other environmental features, Calthorpe recommended their integration into new neighborhoods as something more than edges. This more negotiated, better integrated synthesis of open space, street network, and land use pattern presented much greater opportunity and multiple uses for natural open space beyond simple resource protection or visual amenity. Figure 1.7 illustrates Calthorpe's transformation of the original TOD concept to support a more active role for and more connective pattern of open space. Within it, opportunities were created for natural areas to serve as pedestrian and bicycle corridors that connect many kinds and scales of public space—for example, parks, schools, and town centers—as well as protect important environmental assets at the same time.
Calthorpe's diagram implies a more active relationship between the spatial patterns of open space and built development, making it a contemporary "green neighborhood" prototype. In the diagram, both natural and urban patterns are distinct and legible. Take away the built pattern, and a functional natural pattern remains; take away the natural pattern, and a functional built pattern remains. Taken together, however, a third pattern, created by the integration and interaction of the two, suggests spatial opportunities to strategically merge, layer, or juxtapose built and natural ecologies that might also be better urban places—spatially, functionally, and economically.
Achieving the potential of this emerging view of integrated open and built space presents conceptual and methodological challenges to the planning of urban development patterns. While such planning already embraces many ways to represent the patterns of built form, land use, transportation, infrastructure, and other human attributes in parallel, rarely are ecological forces and open space assets equal partners. Until built and ecological components gain equal status, opportunities to consider where they may work together or where they may compete will continue to be lost.
An Example: The Royal Avenue Plan
New neighborhoods frequently emerge at the suburban edges of cities. At these edges, emerging models of "smart growth" development patterns confront the natural resources and open spaces of rural landscapes. The most common spatial relationship between the two—open space as edge or boundary—insulates the urban from the natural, and the natural from the urban. A more closely integrated spatial relationship facilitates a more extensive and diverse palette of opportunities. Urban areas benefit from the more robust ecological functions near them, and rural landscapes benefit from better stewardship of natural resources. One example, the Royal Avenue Plan in Eugene, Oregon, provides an instructive story of the "greening" of a neighborhood-scale development pattern. The first version of the plan was shaped by land use and transportation in 1998. Over the next five years, it was reshaped to improve its ecological structure, specifically its wetland protection and natural stormwater drainage. Incrementally articulated at each iteration, the influence of these forces was ultimately reconciled in an integrated whole.
Royal Avenue (Figure 1.8) is a familiar example of an emerging growth area at the edge of a small city—in this case, a metropolitan area of about 225,000 people. Like many greenfield development sites in Oregon's Willamette Valley, this area of flat bottomland sits between the existing city limits of Eugene and an urban growth boundary immediately adjacent to valuable agricultural, timber, or natural resource land. This particular site, once annexed, is destined to form part of the western edge of Eugene and the eastern edge of a valuable wetland area.
Adjacent development is typical postwar suburban sprawl. Densities are low, and land uses are spread out and segregated. Street networks are circuitous and poorly connected. Natural features have been destroyed or urbanized—wooded areas have been cleared, streams have been culverted or channelized, wetlands have been filled or fenced, and land has been leveled. Automobiles rule. Transit service is poor, and pedestrian and bicycle facilities are few. Large expanses of impervious surfaces are connected and mechanically drained to channelized drainage ways. Most of what is not paved consists of chemically managed lawns.
Excerpted from Skinny Streets and Green Neighborhoods by Cynthia Girling, Ronald Kellett. Copyright © 2005 Cynthia Girling and Ronald Kellett. Excerpted by permission of ISLAND PRESS.
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Table of Contents
Preface Introduction Growing Compact Growing Green Growing Compact and Green Chapter 1. Green Neighborhoods -Defining Green Neighborhoods -An Example:The Royal Avenue Plan -Network and FabricGreen and Gray Chapter 2. Case Studies -Overview -Radburn -Stapleton -Playa Vista -The Beach -Coffee Creek Center -Orenco Station -Heritage Park -Villebois Chapter 3. Green Networks -Fragmented Systems -Engaging Landscape Ecology -Green Networks and Form -Connecting Region to Neighborhood -Green Networks Strategies Chapter 4. Gray Networks -Gray Networks Impact Pollution -Designing Street Networks -Hybrid Networks -Green Streets -Skinny Streets -Streets as Civic Amenity -Gray Networks Strategies Chapter 5. Gray Fabric -Compact Neighborhoods -Density -Complete Neighborhoods -Neighborhood Diversity -Gray Fabric Strategies Chapter 6. Green Fabric -Urban Forest as Green Infrastructure -Planting Green Streets -Defining Neighborhood Space -Green Fabric Strategies Chapter 7. Urban Water -Sustaining Urban Water -Stormwater as Civic Amenity -Linking across Scales -Whole Water Systems -Urban Water Strategies Chapter 8. Getting to Green Neighborhoods -Thinking, Seeing, and Knowing "Green" -Nested Parcels, Districts, Neighborhoods, and Regions -Integrating Compact Green and Gray: Vancouver, British Columbia -Reflections on Green Neighborhoods Notes Bibliography Index