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Real Property, Trust and Estate Law Journal

Spring 2023

Zoning for Mixed-Use Development

Daniel R Mandelker


  • Mixed-use development combines residential, commercial, and office uses into projects that emphasize diversity and community, accessibility to work and shopping, and public space.
  • Mixed-use development can be planned or unplanned, which is development resulting from the separate, unrelated actions of several different developers.
  • The structure of zoning is an obstacle because it is designed to prevent the mixing of uses.
Zoning for Mixed-Use Development
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Mixed-use development is part of a strategy for sustainable development and good urban form, with the objectives of attaining economic vitality, social equity, and environ-mental quality. A wide variety of zoning alternatives are available, but there is little appreciation of their advantages and disadvantages, how they function, and how zoning should differ with different types of development. This Article provides a roadmap to help lawyers navigate the decisions that must be made to tailor zoning alternatives to the different types of mixed-use developments that occur in the market.

Mixed-use development can be planned or unplanned, which is development resulting from the separate, unrelated actions of several different developers. It can also be vertical or horizontal. This article considers horizontal mixed-use development.

Walkability, a multilayered public realm, inclusive living choices, and authenticity are important for planned mixed-use development. Retail space is a major challenge. Decisions must be made on land use mix, design detail, how markets work, and zoning that will support active retail uses. A compact, walkable urban village is recommended, good design and configuration are essential, and vacancies must be controlled. Office space can be integrated with retail space, built separately as individual structures, or included in an office campus. Social objectives include internal trip capture, which is the measure of the number of trips that begin and end in a development, housing cost issues, and racial and income diversity issues.

The structure of zoning is an obstacle because it is designed to prevent the mixing of uses. Authorizing mixed-use development usually requires a zoning change, which may include discretionary review and approval. A variety of zoning alternatives are available. They include planned unit development, design guidelines, and form-based zoning. Unplanned mixed-use development requires the adoption of zoning districts in which mixed use is permitted, requires attention to scale, and may require a variety of mixed-use districts. Planned mixed-use development requires more zoning detail that can define critical project elements and that may include extensive design controls. Mixed-use zoning can also be used for special development objectives that can include transit-oriented development, mall redevelopment, and live/work units.

I. Introduction

Glenwood Park in midtown Atlanta is a successful 28-acre brownfield development consisting of onsite retail, office, and residential properties. Marketed as “a lively new city neighborhood” and “a compelling alternative to conventional development,” Glenwood Park was designed to be walkable, environmentally sensitive, and convenient for its residents, the employees working in its office spaces, and the customers visiting its retail locations. The ongoing transformation of San Diego County, Cal-ifornia provides several other examples of wide-ranging mixed-use development projects, demonstrating how well mixed-use development can jump-start urban growth. Mixed-use development is a dominant urban form that combines residential, commercial, and office use. It emphasizes diversity and community, accessibility to work and shopping, and public space. Mixed-use development has transformed and revitalized the real estate industry, but has also upended zoning practice.

A wide array of zoning alternatives is available for mixed-use development, but there has been little appreciation of how they function, how zoning requirements should differ with different types of mixed-use developments, and their advantages and disadvantages. This Article fills this gap.

Zoning for mixed-use development is market related, and important decisions must be made on how zoning should control market develop-ment. A minimal zoning strategy provides an opportunity for mixed-use development projects but allows developers to make the development decisions, such as what mix of land uses is allowed. More comprehensive zoning is required if a municipality wants to control the design and character of planned mixed-use developments, which can be done through a variety of zoning techniques, such as design review. Another important choice for any zoning regulation is whether mixed-use development can occur by right, or whether it will require approval through discretionary review. This Article provides a roadmap to help lawyers navigate the decisions that must be made to tailor zoning alternatives to the different types of mixed-use developments that occur in the market.

Part II defines mixed-use development, considers variable applica-tions of that definition, and then discusses its social objectives, including housing cost, diversity, and internal trip capture. Part III explains the particular land use issues that arise in planning mixed-use developments. Part IV explains how to change zoning ordinances to better facilitate and regulate mixed-use development. Part V catalogues four different ap-proaches to mixed-use development regulation and oversight, discussing planned unit development, design guidelines and standards, form-based zoning, and zoning alternatives. Part VI discusses special purpose applications for mixed-use development for transit-oriented development, mall redevelopment, and live/work units.

II. The Concept and Objectives of Mixed-Use Development

A. Defining “Mixed Use”

Jill Grant, who has extensively studied mixed-use development, explains that “‘[m]ixed use’ has become a mantra in contemporary planning, its benefits taken for granted.” She claims that mixed use provides an urban environment active at all hours, a greater range of housing choice that increases affordability and equity, and a reduction in the environmental effects from the use of automobiles by reducing car ownership and use. Mixed use forms part of a strategy for sustainable development and good urban form with the objectives of attaining economic vitality, social equity, and environmental quality.

Mixed-use development is not a standardized product. “It can differ by the nature and combination of uses, the dimension in which the uses are being mixed, the scale at which the mix of uses is occurring, and the urban texture that is created both within the development and throughout the surrounding area.” Professor Grant finds at least three conceptual levels for mixed-use development: increasing the intensity of land use, increasing the diversity of uses, and integrating segregated uses.

There is no universally accepted definition of mixed-use development. The definition differs depending on how land-use categories are defined, how a functional measurement of land use mix is selected, and the scale of geographic analysis, as land use diversity and intensity may differ at regional, neighborhood, street block, or even building levels. A defini-tion by several national development organizations captures the essentials. They define mixed-use development as “a real estate project with planned integration of some combination of retail, office, residential, hotel, recreation or other functions” that “is pedestrian-oriented and contains elements of a live-work-play environment. It maximizes space usage, has amenities and architectural expression and tends to mitigate traffic and sprawl.”

Mixed-use development can be planned or unplanned, deliberate or spontaneous. The Urban Land Institute (ULI) defines mixed-use develop-ment in a way that anticipates a mixture of uses resulting from a deliberate process. ULI defines a mixed-use development as three or more significant revenue-producing uses with significantly integrated physical and functional project components that are developed in conformance with a coherent development strategy and plan. Mixed-use development plans are more complex than for single-purpose development and typically contain a wide collection of materials such as “the types and scale of land uses, permitted densities, and general areas on the site where different types of development are to occur.”

Mixed-use development plans can cover a subarea, such as a down-town or another subarea, an activitycenter, or a neighborhood. They can be included in a comprehensive plan and adopted as a concept plan for a master planned community.

Despite the Urban Land Institute’s definition, mixed-use development also, of course, can be unplanned, “often resulting from the separate, unrelated actions of several different developers.” Unplanned mixed-use development may occur in the absence of interfacing with zoning authorities as long as there is sufficiently flexible zoning applicable to the area that authorizes a mixture of uses. For example, Mukilteo, Washington invites this sort of spontaneous, mixed-use development in designated mixed-use districts. In Mukilteo, amixed-use district is intended to accommodate and foster pedestrian usage by combining commercial/retail uses and residential uses in the same buildings or in close vicinity of each other.

Mixed-use developments can also be vertical or horizontal. Vertical mixed-use development is the mixing of uses in a single building, usually ground floor commercial use and residential upper stories. Vertical mixed-use development can occur in a single standalone building, or in buildings that are part of a horizontal mixed-use development. It requires specialized zoning. Horizontal mixed use-development is the integrated mixing of uses in more than one building. This Article considers horizontal mixed-use development.

B. The Goals of Mixed-Use Development

The success of mixed-unit developments can be measured by how it achieves expected social objectives. Although several social objectives could be identified as metrics for measuring the positive impact of mixed-use development, this section focuses on just three: internal trip capture, which indicates success in internalizing trips within a mixed-use development; housing cost issues; and racial and income diversity.

1. Internal Trip Capture

Internalizing trips is a key social objective in mixed-use development. Internal trip capture, which has been heavily studied, is the measure of the number of trips that begin and end in a development.

Internal trip capture is the portion of trips generated by a mixed-use development that both begin and end within the development. The importance of internal trip capture is that those trips satisfy a portion of the total development’s trip generation and they do so without using the external road system.

Calculating an internal trip capture rate requires building a predictive model with acceptable quantitative variables that can predict the number of trips that are internal to a mixed-use development. It is a significant measure of walkability.

There is no agreement on an optimal trip capture rate, and studies of internal trip capture in mixed-use developments produced mixed results. One set of studies examined a substantial number of mixed-use developments in a large number of regional areas. Results varied significantly, and internal trip capture rates were as low as seven percent and as high as forty-seven percent.

Another study found that larger, denser, and more walkable mixed-use developments had a higher internal capture rate than conventional suburban developments, and that well-designed mixed-use developments had walk shares of more than fifty percent on internal trips. Studies also found that internal trip capture gained from a high value for job to population balance that translated into more opportunities to live and work on site, and from high intersection density that increased routing options, made routes more direct, and created frequent street crossing opportun-ities. Larger mixed-use developments may have higher trip captures because they capture more destinations on site. These findings can provide the basis for design guidelines that help produce good internal trip capture rates.

Even if a mixed-use development does not have a high internal trip capture rate, it can be environmentally beneficial because it offers people more options to live near their work or school that is not in their develop-ment. Trips can be shorter even though a development does not reduce trips through internal trip capture.

2. Housing Cost

“Mix is a necessary but not sufficient condition for achieving good community.”

An important community issue is whether residents in mixed-use developments pay a housing premium. Studies are limited, and the issue is complicated because housing cost premiums vary with the type of mixed-use development studied and its location. A Dutch study of mixed-use neighborhoods in Rotterdam that did not include mixed-use develop-ment found that a good mixture of land uses can increase housing costs by up to six percent compared to the cost of homes in monofunctional areas. A Toronto study that focused primarily on high-rise condominiums in the downtown core found that housing costs were fifty-nine percent and sixty-four percent higher in mixed-use zones when compared with costs for owning and renting in the metropolitan region.

Housing costs in mixed-use developments are offset by lower trans-portation costs. An extensive study of 337 metropolitan regions found that households in more compact neighborhoods enjoyed combined housing and transportation cost savings equivalent up to a ten to twenty percent increase in pre-tax income. Remedial measures can mitigate housing cost issues through community affordable housing programs or by requiring mixed-use developments to provide affordable housing.

3. Diversity

Advocates of compact, high-density mixed-use development claim it increases diversity by spatially integrating various racial and income groups. There is some support for this claim. Compared with residents of car-oriented suburbs, residents of walkable, mixed-use neighborhoods have increased community cohesion. They are more likely to know their neighbors, participate politically, trust others, and be socially engaged. A South African study found that mixed-use development significantly increases diversity, income equality, mixed tenure, diversity of modal choices, public motorized transportation, non-motorized transportation, and decreases private motorized transportation.

III. Planning Considerations for Mixed-Use Development

Walkability, a multilayered public realm, inclusive living choices, and an authenticity that defines a community and its setting are critical for planned mixed-use development. Walkability, density, and compact-ness must be integrally connected and central in order to promote retail space and the other factors that mark successful urban places. Walk-ability is the defining threshold ingredient, and “[a] walkable urban place needs a critical mass of people, disposable income, and activity to draw the full community and function as a center for community life.”

A. Retail Use

Retail space is a major challenge. Decisions must be made on what to put in the land use mix, providing design detail where it is needed, learning how markets work, and supporting zoning for active uses. Providing successful retail space is complicated by changes in retail marketing, especially the rise in e-commerce, the decline in auto-oriented mass market retail, and an increasing focus on food and drink with niche retail that responds to the values and tastes of the surrounding community. Adaptation is necessary.

A choice must be made between destination and local retail. Destination retail relies on a customer base located outside a mixed-use development; can be expected to survive only in top-tier, highest-trafficked locations; and can have criteria for identifying locations that may not include mixed-use developments. Some mixed-use developments decide to include only local, independent, community-based retail, which has been recommended.

Density is an important issue because residential density must be high enough to support walkability. A compact, walkable urban village is recommended that has a radius based on how far people will travel. The radius should be less than a half-mile in order to encourage utilitarian walking trips less than ten minutes in duration. This development model requires an urban village with a density of 5,000 to 10,000 residents, or 2,000 to 4,000 homes in a 250- to 350-acre walkshed. Office space can also provide retail support, but an office area requires twice as much space to support the same amount of retail space. Some developers do not rely on fixed formulas but use intuitive judgment to decide on the size retail space and what it should contain.

Good design and configuration are essential. Retail space must attract an adequate threshold demand, be compatible with a mix of comp-lementary uses, and be vibrant, pedestrian friendly, and experience-driven with active ground floor space. A choice must be made on how design should be determined. Developers can be allowed to make design decisions without guidance from the municipality, or the municipality can adopt design guidelines for mixed-use developments that cover design issues such as scale, physical form and massing, and building heights, setbacks, and facades.

Vacancy rates can be a problem. An early Seattle study that did not include development size as a variable examined multiple, unplanned, and moderate-size projects distributed throughout the city in response to a zoning change. Though limited and dated, its conclusions on vacancy rates are instructive, as it found that forty-seven percent of the commercial space in built mixed-use projects was vacant.

The Seattle study indicates the importance of vacancy control, and vacancy issues require a municipality’s attention to the market. Montgomery County, Maryland does not have a serious problem with vacant storefronts, largely because of an aggressive planning program. “The county regularly studies the local retail market, prepares annual reports analyzing issues within its downtown planning districts, and maintains flexibility about what constitutes ‘active ground-floor uses.’” Municipalities should also require an analysis of market conditions by requiring developers to submit an economic feasibility study that a municipality can use when deciding whether to approve a mixed-use development. Zoning for mixed-use development is market-related.

Retail is fluid. Decreasing demand due in part to an increase in e-commerce, shifts in retail use, and problems with retail turnover require adaptation and flexibility that can anticipate changes in retail space. Flexibility includes redevelopment to replace anchor and large space stores that close with smaller and more adaptable retail space, and design changes such as smaller storefronts because in-store e-commerce shipments reduce space needs.

Zoning flexibility can deal with these problems. “Ground floor frontages can be designed and zoned for nonresidential/retail development without requiring that they be occupied by these uses, so that the market can fill or not fill these spaces over time.” Expanding the permitted nonresidential use list to add additional nonresidential uses such as entertainment and food, craft brewing, artisan workshops, museums and galleries, shared commercial kitchens, and offices improves the appeal of nonresidential space and helps to avoid vacancies.

B. Office Use

Mixed-use developments can include office space, which can be integrated with retail space, built separately as individual structures, or included in an office campus. Changing trends in office development have changed how office development is built. The single purpose suburban office park that once dominated the market is obsolete. It fell out of favor because of shifting employee preference for a mixed-use environment; employer preference for spaces that are flexible, sustainable, and adaptable to their daily needs and long-term goals; and a preference for projects that appeal to a wider pool of potential tenants.

Zoning changes similar to those suggested for retail space are needed. They can improve flexibility by simplifying setbacks, increasing allowable building height, allowing mixed uses, and adding design guidelines that can address building form, the relationship of buildings to each other, and unifying architectural details. Riverwalk in San Diego is primarily a mixed-use office development with limited retail and residential use.

IV. The Zoning Challenge

A municipality that wants to adopt a zoning ordinance that can effectively regulate mixed-use development faces a complicated task. Decisions must be made on two important issues. The first issue is whether to allow mixed-use development by right without discretionary review, or whether to allow mixed-use development only after it is approved through a discretionary review. The second issue is whether to rely on zoning that provides only an opportunity for unplanned mixed use development, on zoning that provides detailed design guidance for planned mixed-use development, or a combination of both. This section discusses these issues and begins by discussing the structure of zoning.

A. The Structure of Zoning

Mixed-use development occurs naturally in the urban environment. It presents a zoning problem because zoning as originally conceived was limited to ensuring that “nearby uses were not harmful to each other,” and mixed uses could possibly be harmful to each other. Zoning carries out a harm-preventing purpose by separating industrial, commercial, and residential uses, a practice upheld in an early and influential Supreme Court case. Use separation is provided through zoning districts authorized under legislation based on the model Standard State Zoning Enabling Act, which most states adopted, and which confers the authority to divide a municipality into districts to “carry out the purposes of this act,” and within such districts to regulate the construction and use of land.

Non-cumulative zoning is another barrier. It is not required by the model zoning statute but has become the dominant zoning practice that limits each zoning district to permitted exclusive uses, which are usually a narrow range of uses permitted by right or as a conditional use. Expanding the range of uses allowed in each zoning district can remedy the noncumulative zoning problem, but this change will create a uniform-ity problem. Zoning statutes based on the model law require that zoning regulations must be uniform throughout a zoning district, and allowing mixed-use development in a zoning district could violate this requirement. There is some judicial support for a contrary view holding that a mixed-use district does not violate the uniformity requirement if it is reasonable and based on public policy.

Zoning was expected to be self-executing, nondiscretionary, and by right. Uses within a district were to be permitted by right without discretionary review. The problem is that the by right system of zoning is no longer dominant. All intensive development now occurs through zoning or administrative changes that are “applied for and granted on the threshold of development.” The difficulty is that these administrative changes are not adaptable for mixed-use development. Zoning legislation authorizes the administrative approval only of hardship variances defined by statute, and special exceptions, also known as conditional uses under criteria provided by the zoning ordinance.

Zoning ordinances can also be amended by map amendment, a change in the zoning map that moves a tract of land from a zoning district where it is not permitted to a zoning district where it is permitted. Map amendments can permit mixed-use development, but they are legislative decisions in most states and cannot regulate project detail. Some control of project detail can be obtained in states where conditional zoning is authorized, or through floating zones, which are zoning districts included in the text of a zoning ordinance but mapped only when they are individually approved. A mixed-use development district can be adopted as a floating zone. A zoning ordinance also can require the approval of a development plan for a mixed-use development.

B. The Zoning Process

Zoning change is usually legislative and does not require an administrative process, but discretionary administrative review and approval of land use change does require administrative process. Procedures vary but can include adequate notice, a hearing by a neutral arbiter, the right to present evidence, the right to cross-examine witnesses, the right to respond to written submissions, the right to counsel, and the right to a decision on the record with stated reasons.

Public hearings can create problems. Public participation to present a public point of view is critical, but public hearings increasingly are a significant obstacle to new development, including mixed-use develop-ment. Problems with public hearings are highlighted in a recent Massachusetts study that found that public hearings offer opponents ample opportunities to stop or delay projects and to force damaging change. Opposition occurs not only to large and controversial projects but to the modest and mundane, and by an unrepresentative group of homeowners.

Change is needed in the administrative land-use process that will reform the system and control undisciplined hearings. A pre-application conference with the developer and neighbors can resolve problems that could trigger opposition. Municipalities can control the hearing agenda by listing the issues that the hearing will consider in the hearing notice. Agenda control limits undisciplined opposition because issues not related to the agenda cannot be considered. Clear and objective standards for discretionary review can prevent opposition built on baseless claims. Time limits on decisions and the encouragement of written testimony are additional helpful requirements. Litigation is another option. It can challenge a project denial that is unsupported by legitimate zoning concerns, though litigation can be expensive and cause delay.

V. Zoning Strategies for Mixed-Use Development

This section discusses four different zoning alternatives that can facilitate the regulation of mixed-use development. There is no single metric that determines which alternative is optimal. The alternatives vary in how they manage the issues identified earlier, which are how much control to exercise over mixed-use development and how much discretion to build into the zoning system.

A. Planned Unit Development

Planned unit development (PUD) is an alternative to traditional district-based zoning. It is a discretionary review process that can be used to approve a planned mixed-use development and to approve a development plan for the development. The development plan controls how the mixed-use development will be built. Municipalities can exercise control over the design of a planned unit development by adopting criteria that specify the planned unit developments they will approve and the contents of development plans. The criteria can include requirements for the objectives and character of a PUD; its residential and nonresidential development and their location; and a circulation plan that details walkability, public space, and architectural design. Amendments to development plans must be authorized to ensure flexibility in development.

There are advantages and disadvantages to approving a mixed-use development as a planned unit development. An important advantage is that the development plan adopted for a mixed-use development can customize the land-use and design criteria that will shape the development. Zoning ordinances and design guidelines cannot provide this customized detail.

Planned unit development has disadvantages. It often is a negotiated process between a developer and the municipality, which can produce arbitrary decisions. Discretionary review can cause uncertainty, delay, and opposition. Practitioners who work with planned unit developments have had mixed experiences with discretionary review. Problems also arise with multiple approvals because staff must keep track of many distinct sets of regulations for different projects instead of a uniform set of zoning rules.

B. Design Guidelines

Design is the catalyst that brings planned mixed-use development to life because it considers appearance, form, and function and describes the design qualities that mixed-use developments require. There are design standards and design guidelines. Design standards are prescriptive, mandatory, and quantitative, are similar to site development and density requirements contained in zoning ordinances, and are a necessary element for mixed-use development regulation. They describe the basic building envelope with specific, quantified, and limited textual requirements such as setbacks, building heights, floor area ratio, density, and intensity. A twenty-foot setback requirement is an example.

Design guidelines detail the design essentials for mixed-use developments. They can be adopted as a separate guideline or integrated into the zoning ordinance, and they can be objective or subjective. There are advantages and disadvantages to either approach. Objective design guidelines provide measurable standards but can produce unacceptable design outcomes if they are rigid and do not allow an opportunity for creativity. Subjective guidelines are not measurable and are indeter-minate, qualitative, and subjective. They address design elements that cannot be measured easily or quantified, such as site design, building proportion and massing, access and circulation, and architectural express-ion.

Subjective design guidelines provide flexibility but can produce arbi-trary decisions if not drafted precisely. Precise drafting is necessary to avoid claims that they are an unconstitutional delegation of power or that they violate substantive due process because they are too vague. Courts have upheld design guidelines when there is a reasonably comprehensive attempt to provide guidance. Detail level must also be considered. Heavily detailed guidelines may suppress development if they unnecessarily prevent development that the market prefers. Lightly detailed guidelines may not provide enough control over development design.

Compliance can be enforced through the normal development review administrative process, which can be done through staff review but which can require a hearing or the consideration of written objections. Design review is an alternative discretionary review process that usually includes an architectural review board that decides on compliance. Review under either alternative can be problematic because it can generate the uncertainty, delay, and opposition that can occur in any discretionary review process.

Castle Pines, Colorado, is a good example of a comprehensive set of design guidelines. Policy for locating mixed-use development is provided by the comprehensive plan. The guidelines include four design elements, which are site planning and design, access and circulation, architectural design, and landscape design. Design principles include community character, balance, placemaking, sustainability, and pedes- trian activity and connectivity. A guideline for street design, for example, states that, “[t]he intent of these Design Guidelines is to develop a ‘main street’ character within each mixed-use development by creating pedestrian-oriented streets where possible.” Architectural design includes the relationship between buildings, façade modulation, building height and massing, and building materials and colors. Architectural character is covered by a guideline stating that “[t]he placement, size, form and orientation of new buildings should be coordinated to create visually cohesive spaces with a variety of materials, colors and features.” Block length and site coverage also are included.

C. Form-Based Zoning

Form-based zoning is a popular and widely adopted zoning program which, like mixed-use zoning, claims a walkable, pedestrian-oriented development as a major objective. Form-based zoning is an alternative to traditional zoning because traditional zoning regulates only land use compatibility and may not create the physical character and scale needed for new development. As defined by the Form Based Codes Institute: “Form-based codes address the relationship between building facades and the public realm, the form and mass of buildings in relation to one another, and the scale and types of streets and blocks.”

Form-based codes are “keyed to a regulating plan that designates the appropriate form and scale (and therefore, character) of development, rather than only distinctions in land-use types.” The plan has a specific future development map and is similar to a detailed development plan or preliminary plat. Drawings and explanations of building types may be included, and development is limited to these building types. There is no standard model for form-based zoning. It varies considerably, may not include a regulating plan, and is seldom adopted in its pure format.

Form-based zoning covers some, but not all, of the planning and design elements required for planned mixed-use development. It is limited in its application to mixed-use development because it deemphasizes land use as the focus of regulation. Simplified use tables tertiary to the form standards are recommended that are not the primary regulation, and generalized use types are also recommended. A prominent advocate of form-based zoning goes further and states that, “[t]he most effective [form-based codes] replace use-based zones with form-based zones.” Other traditional land use regulations are downplayed, and regulation of land use density is deemphasized, though this recommendation is not always followed. Floor area ratios are not used, and this omission is criticized.

Form-based zoning discourages design detail and design guidelines, which also are needed for mixed-use development. It is intended as a prescriptive set of regulations available by right that avoid the problems created by discretionary review. While administrative relief through variances and a deviation called a warrant are nevertheless available, they can overwhelm the system and they can create problems of uncertainty, delay, and opposition.

Despite recommendations against a focus on use, form-based codes usually include extensive use controls. They just are more flexible and inclusive than those typically included in a traditional use-based code. In practice, most contemporary codes adopt a hybrid form of zoning that blends form-based standards with more traditional use-based standards and that combines the advantages of form-based zoning with traditional zoning. North Miami Beach is an example. It added regulating plans and building types to its mixed-use zoning districts and requires a neighbor-hood master plan. Mooresville, North Carolina blended form-based zoning with traditional land-use controls, including a mixed-use district. It has general and specific building form standards and a typical land-use matrix, but does not require regulating plans.

D. Zoning For Mixed Use

1. Zoning for Unplanned Mixed-Use

Unplanned mixed-use development is development by the separate, unrelated actions of several different developers and requires the adoption of zoning districts in which mixed-use development is permitted. As Donald Elliott explains, the key advantages of mixed-use districts “can be achieved by simply opening up those opportunities rather than requiring a particular type or mix of development.”

Scale is important. To manage scale, Elliott generally prefers zoning a range of mixed-use districts organized by size, including a small neighborhood scale, a medium community scale, and a large scale for regional or major redevelopment areas. He may control space by limit-ing the area available for residential use so that it does not dominate the zoning district, and by limiting residential use only to upper stories on key street segments where non-residential ground floor uses are particularly important. Mixed-use zoning adopting this strategy minimizes regulation, may or may not regulate design, and leaves most development decisions to developers.

Elliott’s mixed-use zoning for Bloomington, Indiana illustrates his approach and includes a variety of mixed-use districts, including neighborhood, medium scale, and downtown districts. The Mixed-Use Neighborhood Scale district, for example,

is intended to promote a mix of neighborhood-scale residential, commercial, and institutional uses with pedestrian-oriented design and multi-modal transportation availability, in order to promote context sensitive neighborhood-serving development at nodes and corridors near low- and medium-density residential neigh-borhoods.

Use Regulations are contained in a separate chapter and include an Allowed Use Table. The Table designates permitted, conditional, and accessory uses for all districts, including the mixed-use districts, where it provides a mix is appropriate to the district’s purpose. Typical dimensional standards are provided and include lot dimensions, building setbacks, and other standards such as impervious surface coverage. The ordinance adds building design standards such as standards for exterior finish, facades, eaves and roofs, and anti-monotony standards.

Minimal zoning that is limited to authorizing mixed-use development avoids the problems of more detailed regulation but can create problems because it leaves major development decisions to the market. Zoning can provide greater control over unplanned mixed-use development by adding design requirements, such as comprehensive form-based standards that control building mass and facades and streetscape, equity-driven zoning that eliminates single-family zoning, and design criteria that define the character of mixed-use developments or that require pedestrian connectivity. The Bloomington ordinance adopts some of these options. Alternatives to by-right zoning can provide more control, such as a floating zone. This alternative provides flexibility because it is not approved until a developer makes an application for approval, which allows the municipality to consider whether to approve and to modify the application.

2. Zoning for Planned Mixed-Use Development

Zoning for planned mixed-use development requires enough detail and control that will define critical project elements. It can provide the same kind of guidance that is provided by design guidelines, but it has the detail problem and requires a choice between objective and subjective criteria.

Montgomery County, Pennsylvania’s model New Town Mixed Use District is an example. It “is designed for places where compact, walkable, livable, and attractive development is appropriate.” The key elements are a wide variety of permitted uses, a diverse mix of uses, an attractive central plaza, pedestrian friendly building design, unobtrusive parking, appropriately scaled height, and a significant scale of development. District regulations cover use and use mix, dimensional standards, and design standards that include general layout, building design, parking, and pedestrian design.

Zoning for planned mixed-use development can be extensive. The Dublin, Ohio Bridge Street District is a 127-page form-based code that implements a Bridge Street District Area Plan with detailed design guidelines for a densely developed, walkable, mixed-use planned develop-ment in a 1000 acre historic center. The Code’s General Purpose includes Principles of Walkable Urbanism and an Urban Design Framework that describes Walkable Focus Areas with three types of character emphasis.

VI. Special Purpose Mixed-Use Zoning

There are a number of special purpose land use programs that include mixed-use development and that have specialized land-use requirements. This section describes a few examples. They are examples of zoning for unplanned mixed-use development, but more detailed zoning for unplanned mixed-use development is an alternative.

A. Transit-Oriented Development

Transit-oriented development (TOD) “is generally defined as development close to transit stations or transit stops that is compact, mixed-use, pedestrian-friendly, and well integrated with transit.” It is intended to encourage transit usage, and transit-oriented development near transit stations must be resident-dense and job-dense because transit usage is driven by residential and employment density. Walkability is critical: “The critical thing about making TOD work is to ensure that development actually is oriented around the station. That means enabling people to walk easily between the station and the destinations it serves.” Mixed-use promotes walking. TOD is planned mixed-use development.

TOD zoning districts are categorized in a variety of ways, such as by transit type or the type of community in which the transit station is located. The range of development density and the mix of allowable land uses typically defines TOD within these categories. A TOD ordinance can either be an overlay district or a primary base district. It usually has a center located around a transit station that has the highest density and use concentration, and a peripheral area with lower densities and a narrower range of land uses, such as a residential or employment district. Model zoning ordinances for TOD zoning districts include the standard zoning regulations but vary in whether, and to what extent, they have design standards. One proposed model TOD ordinance is similar to the New Town Mixed Use District ordinance. The ordinance requires existing or approved principal uses from at least two nonresidential use categories and High-Activity Nonresidential Uses at Street Level and has development and design standards, connectivity standards, and building and design standards, but includes detailed design standards. Design guidelines, integrating TOD with planning or approving a TOD as a planned unit development are alternatives.

B. Mall Redevelopment

The large-scale, country-wide abandonment of single-purpose shopping malls creates opportunities for mixed-use development because they contain large, open parking areas that are available for conversion. As Lee Einsweiler explains, mall conversion of “suburban” commercial areas with sprawling parking lots, awkward circulation and limited street connections, mostly on major road corridors, requires rezoning. “Transformational change” is needed that will convert open, undeveloped parking areas to mixed-use development with designated centers. New blocks and streets are part of the change when parcels are large enough. Einsweiler’s zoning ordinance for Amherst, New York applies these concepts. Mall redevelopment can also be done under a design-based zoning ordinance or a development plan.

C. Live/Work Units

Live/work units, which are housing units where individuals both live and work, are an important mixed-use development because they decrease automobile use and increase internal trip capture. They require regulations that designate where they can be located and that include regulations for use and occupancy. This zoning usually is by-right zoning, but discretionary review can be required. When zoning is for planned mixed-use development, it can indicate where live/work units are appropriate in a mixed-use development and can provide development and performance standards that limit nonresidential use so the live/work unit is compatible with adjacent residential uses. Municipal zoning ordin-ances can include lists of permitted uses for live/work units and detailed performance and development standards that can include detailed reg-ulations for use, occupancy, and employment.

VII. Conclusion

This Article has discussed the zoning alternatives that are available for mixed-use development. Decisions that must be made on when to apply these alternatives should not discourage their adoption. There is no standard metric that can identify a successful one-size-fits-all-model, all zoning strategies contain risk, and zoning always requires adaptation that depends on the type of mixed-use development the zoning ordinance is intended to achieve.

Zoning for mixed-use development must consider the issues discussed in this Article. Decisions must be made on how much control the municipality wants to have over mixed-use development, and whether that control should authorize development by right or require discretionary review. The degree of control provided determines the extent to which a municipality can accept or modify development decisions in the market.

The decision on how to define discretionary review, if it is adopted, determines how much flexibility there is in regulating mixed-use development, how much certainty is provided, and the level of detail in development requirements. Discretionary review provides an opportunity to customize regulation for individual projects but creates uncertainty. By-right zoning provides certainty but not the customized detail that a mixed-use development needs.

Zoning for mixed-use development requires difficult choices, and there is no standard metric for making these choices. They must produce zoning for mixed-use development that reflects local goals and objectives and the extent zoning is expected to regulate the market. Creating the right zoning framework for mixed-use development can be complicated, but the social, economic, and developmental benefits of mixed-use development make it worthwhile.