Designing the urban preserve boundary: the city of Phoenix learns valuable lessons on how to develop and provide access to open lands in urban areas.

On Oct. 8, 2003, the Phoenix City Council adopted a text amendment to the zoning code creating design guidelines for private development adjacent to the 21,500-acre Sonoran Preserve, an urban desert preserve in Arizona. This was the latest step in a five-year journey led by the park and recreation department. Why would the parks staff invest this kind of time, resources and energy stewarding a change to the zoning ordinance for what could be considered private lands beyond the department's concern? Because the impact of private development decisions on operations, management and ecological health of preserve lands is a major public policy issue that the department needed to address. The department set out to deal with this concept in partnership with the community, Arizona State University, the development interests and the largest land owner in the city's growth area--the Arizona State Land Department.

The city of Phoenix Parks and Recreation Department (PRD) has a long history of acquiring and managing open space, and many lessons have been learned along the way. With the goal and challenge of acquiring additional open space, the city has taken the opportunity to revisit how the interface, or the edge, between the preserve and development is handled. It has become clear that current public policy does not influence the design of residential neighborhoods in relation to adjacent parks and preserves.

Phoenix adopted the Sonoran Pre serve Master Plan (SPMP) in 1998 and is fully engaged in the implementation of the plan (www.ci.phoenix.az.us/PARKS/sonoran.html). This effort received national attention in 2000 when it was given the American Society of Landscape Architects Presidential Award of Excellence for analysis and planning.

Building on more than 79 years of experience in managing urban preserves and the goals of the SPMP, PRD has initiated a review of the condition of the preserve edge. The edge is defined as the line between preserve or natural open space, and development. The park and recreation board, Phoenix Sonoran Preserve Committee, Planning Commission, several city departments and the local university have been active participants in this new policy initiative.

The city of Phoenix has a population of 1.2 million spread over 500 square miles. Within this low-density development pattern, publicly owned preserves become stranded (Photo at left). Phoenix has been setting aside desert mountain preserves since the 1920s, but as a result of this low-density development pattern, popular trails are difficult to access, typically surrounded and backed onto by single family residential developments. The assumption on the part of developers and homeowners living at the preserve edge has been that public access and increased density will increase crime.

The city's SPMP calls for "an integration of a preservation ethic into the overall urban form." This statement lays the groundwork for a departure from the common interpretation that nature starts where the city ends.

The Sonoran Preserve creates the potential for more than 150 miles of edge. The PRD and preserve activists, pushing for more public access to the preserves, have recently worked with the city to adopt Design Review Guidelines (DRG) mandating a 60 percent public/40 percent private rule for development adjacent to a portion of the new preserve. The DRG ordinance proposes four options to meet this 60 percent requirement: (1) single-loaded streets adjacent to the preserve; (2) cul-de-sacs opening to the preserve; (3) private open space adjacent to the preserve; and, the catchall, (4) creative options.

Existing Preserve Edge

Despite debates about access and use, there is widespread enthusiasm for preserving desert. There is much less agreement, however, about what to do at the edge in terms of responding to urban development. Because Phoenicians are accustomed to low-density, single family, detached homes, many people assume this should be the primary development type along the urban side of the preserve boundary.

The existing urban edge condition primarily consists of single family houses with backyards oriented to the public preserves (Photo above). Six-foot concrete block walls generally articulate this interface between preserve and yards. Newer developments have introduced the use of "view fences," metal pickets four inches on center that allow the occupant to see the preserves. Public access points, however, are few, very far apart, not well-defined, and often have inadequate amenities for users.

Frequent conflicts arise when land owners feel their privacy is compromised by preserve users, while preserve users believe their recreational experience is negatively impacted by the sterile design on the private side of the edge. Invasive plants, often propagated in these same backyards, domestic pets, and modifications to natural drainage patterns present additional challenges for park managers whose concerns focus on preservation and conservation of the public resource--natural open space.

The ASU Studio

For assistance in tackling this urban design challenge, PRD turned to Arizona State University's (ASU) College of Architecture and Environmental Design (CAED). In fall 2001, the CAED architecture and landscape architecture faculty at ASU conducted a cross-disciplinary urban design studio. Funded by PRD, the studio explored ways in which design could inform new policy for development at the edge of the Sonoran Preserve.

The city's charge to the studio was to explore the possibility of accommodating both urban and ecological functions in a coordinated and spatially merged form that treats both sides of the edge as environmentally and culturally significant. The studio was asked to develop alternative concepts of what could be built, as well as develop a framework for evaluation of alternatives considering ecological impacts, economic realities, social issues and visual access. The studio also explored policy and implementation strategies. The PRD's challenge presented a unique opportunity to develop a design-driven policy that addressed the complex issues affecting development at the preserve edge.

The studio proposed three interrelated components: (1) Housing--suggestions regarding how developers might build housing near the desert edge, (2) The Edge--ideas about how other types of public and private development should be built at the desert edge, and (3) A Plan--a notion for an overall strategy for coordinated planning for the preserve and future urbanization. A fourth proposal, to refine the DRG crediting system adopted by the city, was also introduced in an effort to provide incentives for the first and second components.

* Housing: The current dominant housing typology, low-density single family detached, intensifies the feeling of a sprawling city consuming the natural landscape, and inherently supports conflicts between public access and community privacy. The ASU proposal suggests that developers consider single family housing types other than detached houses; that the city allow more density at select points along the edge; and, that density be coordinated with non-residential development (i.e. parks, schools and retail) to increase the feeling of community in harmony with the natural environment.

* The Edge: A sense of public access to open space is imperative. Access should be of many different types: distant views, scenic corridors, interpretive facilities, a variety of trail heads and amenities, active pedestrian-oriented urban edges or paseos, (Photo next page), and neighborhood pedestrian access points. Developers should be able to count on city improvements in the plan, and their projects should respond to opportunities presented by public open space.

* A Plan: The plan would assess Sonoran preserve land, consider adjacent open space, understand the need for access, and develop a strategy for guiding urbanization at the edge. Without this plan, it is unlikely that the private sector would deviate from traditional development approaches.

* Weighting System: The current DRG requires that 60 percent of tire edge along open space be left unbuilt. ASU proposes a refinement of the guidelines, allowing developers more flexibility while asking for more creative visions for living at tire edge, by introducing weighted credits and an expanded number of different open space edge treatments.

The weighting system is designed to create incentives. Careful placement of enhanced public access seems appropriate for such an important public resource, and will actually improve the privacy and safety of communities near the preserve. Furthermore, in an effort to encourage areas of intensity at appropriate points along the edge, the weighting system gives developer's incentive of up to double credit for desert paseos with mixed use development. Such places could become great examples of coordination between the public and private sectors, where the public benefits from creative development near the desert, while private enterprise fully capitalizes on the same asset.

Design, Policy and Education

The problem of urban/preserve edge interface is real and very challenging for the park and recreation professional. PRD and ASU joined together to tackle this urban design question. The charge to the studio was to explore the possibility of accommodating both urban and ecological functions in a coordinated and spatially merged form that treats both sides of the edge as environmentally and culturally significant. As an educational opportunity for students, this project was a challenging academic adventure.

PRD looked to ASU for both fresh ideas and political salve. The studio had meetings with more than 20 different groups, including political activists, city departments, lawyers and lobbyists, developers and homebuilders, land owners and residents. Students experienced firsthand the difficult reality of client demands and public work. While fresh design ideas were the ultimate desired product, the students noted that the constraints and contradictions at times seemed overwhelming. The various "clients" did not always trust the motives of other stakeholders or listen carefully to suggestions.

The frustrations with the process are now somewhat mitigated by the fact that the studio and the park department persevered, and the city council has adopted several of the ideas from the study into permanent public policy. A certain amount of satisfaction goes along with this since the ordinance was unanimously approved with backing from a broad range of stakeholders. This is truly cutting edge policy and urban design--the results will play out over the next few years and will be interesting to watch unfold.

Student contributors to ASU's studio included: David Alameddin, John Annos, Lyndsey Bottoms, Juan Brenes-Garcia, Scott Carson, Merlin Ellis, Eric Hansen, Alexander Hill, Jin-Ok Kim, Jaebeom Koh, Stijn Koole, Theresa Labus, Nang New Ma, Paul Michaud Seog-Young Oh, Alexander Plishner, Brian Schroeder and Carl Whaley.