New zoning codes – the District is not alone (part III) Reply

Part 3 of our “the District is not alone” series, where we head down south to beautiful Miami.

Miami’s new code, dubbed “Miami 21,” was developed over a period of five years and included over 500 public meetings before finally being implemented in 2010. Of the three codes examined for this blog post, Miami 21 most radically differs from the District’s ZRR in that it is the largest and most comprehensive example of a form-based code in the nation. Form based codes are predicated on physical form rather than on use. Prior to Miami 21, Miami’s zoning code was a conventional “Euclidian” model, characterized by establishing and regulating land based on use (the District, like most jurisdictions in the US, uses the Euclidian model). According to the Form-Based Codes Institute, under certain circumstances form based codes allow for a dynamic mix of uses because its emphasis is on the appropriate form and scale (and therefore, character) of development, rather than on separating uses. However, some critics say that depending upon the quality of the code and its diagrams, form-based codes can be difficult to interpret and administer.

Downtown Miami (photo: Marc Averette)

Downtown Miami (photo: Marc Averette)

According to the Institute of Sustainable Communities, Miami’s prior code included antiquated parking requirements and inflexible separation between the places where people live, work, and shop. This resulted in automobile dependent communities, traffic congestion, and urban and suburban sprawl. Nancy Stroud, legal counsel to the team that created Miami 21, noted that a major impetus behind Miami’s decision to write a new code was to provide developers and residents with more predictability during the development process. Stroud says that in contrast to the prior code, which provided too much discretion to planning and council boards, Miami 21 simplifies the development process and makes it more transparent.

Miami 21 attempts to mitigate these issues and manage the city’s growth through the concept of transects, an idea promoted by planner/architects Andres Duany and Elizabeth Plater-Zyberk and the Congress for the New Urbanism (CNU) as an alternative or revision of conventional use based zoning. Their idea was to substitute conventional zoning’s focus on use with a focus on the relationship between the form and density of the built environment (a high rise is not appropriate in the middle of the wilderness, just as a single-family bungalow makes no sense in the middle of Manhattan). A transect is a sliding scale between rural wilderness and dense central cities; it defines a series of zones that transition from sparse rural farmhouses to the dense urban core. The transect manages the relationships of buildings to the streets, to open space, and to each other. Miami 21 uses the transect model to enhance neighborhood character and walkability through emphasis on concentrating development along transportation corridors, neighborhood centers, and urban cores.

Within Miami 21, each transect zone regulates the following:
• Building disposition—where the building sits in relation to the lot or parcel;
• Building configuration—how the building is molded (its shape and form);
• Function and intensity—uses allowed in each transect zone and the percentage of the building that may accommodate that use and/or varying degrees of that use;
• Landscape standards;
• Parking standards;
• Standards that integrate individual property with the public realm—such as pedestrian orientation, parking liners, building frontages, and others; and
• A sequential relationship between transects—prior and subsequent transects are related and increase in their intensity, ensuring a smooth succession of environments.


Caption: Miami’s rural to urban transect (top) and an illustrative plan showing its intended results (bottom) Source: DPZ

Caption: Miami’s rural to urban transect (top) and an illustrative plan showing its intended results (bottom) Source: DPZ

Miami’s new code is similar to the District’s proposed regulations in that it is geared to ensure sustainability, predictability and efficiency in development, growth and planning. Like the District’s Green Area Ratio and pervious surface requirements, Miami 21 encourages sustainable building practices. In addition, Miami 21 strives to make neighborhoods pedestrian-friendly and concentrates development along transportation corridors, neighborhood centers, and the urban core. It also ensures that transitions exist between development zones, permitting gradual increases in density from single-family residential areas to the downtown core. Like the District’s proposed regulations, Miami 21 includes provisions for mixed-use areas to provide retail and services within walking distance of neighborhoods. Finally, Miami’s code is written in an easily accessible way; it uses plain language and clear diagrams to convey zoning concepts.

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