Land Subdivision

The design of land subdivisions may be viewed as a special case of site planning, often involving large tracts of land ranging in area from 80 acres to 1,200 or more acres. The process of land subdivision may be described as the division of land into smaller parcels, usually for the purpose of urban development. Land subdivision, however, is more than a means of describing, marketing, and taxing land; it is, in effect, the first step in the process of building a community. Much of the form and character of a community is determined by the quality of its land subdivisions. Once land has been divided into blocks and lots, streets constructed, schools and park sites dedicated, and utilities installed, the urban development pattern is established and is unlikely to be changed. Residential, commercial, and industrial structures will be built on the sites created by the land subdivision. After many decades of use, some of the structures may be razed to make way for new structures and, thereby, accommodate new uses. Yet the street pattern established by the initial land subdivision will probably remain basically unchanged. For generations the entire community, as well as the individuals who occupy the subdivision, will be influenced by the quality of its design and by the character of its improvements. Many of the environmental problems that affects communities, such as traffic congestion, drainage, flooding, high street and utility operation and maintenance costs, inadequate park and school sites and facilities, high fire and police protection costs, and urban blight may be directly attributable to the manner in which areas of the community were originally subdivided. Just as important, in this respect, in the design of land subdivisions is the issue of whether or not the areas concerned should have been subdivided at all. The scattering land subdivisions—often referred to as urban sprawl —located too far from essential community services such as sanitary storage, water supply, fire and police protection, emergency medical services, public transportation and schools, not only create a less desirable place in which live and work, but also tax the resources of the community in attempting to furnish the necessary public facilities and services. The continued availability of agricultural areas may also be destroyed through scattered land subdivision development. Also important in this respect is the issue of whether an excess of building sites is being created at any one time, thereby leaving the community with scattered, partially developed neighborhoods.

The community is required in one way or another to provide the public facilities and services that make urban life possible. Therefore, the community should be able to require that street rights-of-way and roadway pavements be wide enough to accommodate firefighting, emergency service, solid-waste collection and snow removal equipment; that street configuration, grades, and curves are adequate for the safe movement of traffic, good access to building sites, and snow storage; that building sites are adequately drained and not subject to flooding; and, if public sanitary sewer facilities are not be provided, that lots are of sufficient size and have soil characteristics that can accommodate on-site sewage disposal facilities without creating a public health hazard. Land subdivisions will have impacts extending beyond the site boundaries and the subdivision itself, and the community should be able to require that the developer bear a fair and proportionate share of required off-site improvement costs, considering the impacts of the proposed subdivision development on arterial traffic, on sanitary sewerage conveyance, storage, and treatment facilities; on water supply transmission, storage, and treatment facilities; on stormwater management facilities; and on school, library, and park facilities. Subdivision development will also have important fiscal impacts. These impacts may be positive or negative, depending on whether the revenues obtained from the new development exceed the costs of the facilities and services to be provided or are less than those costs. In the latter case, some development may results in higher incremental costs of services than the taxable value of the development may provide in revenues. The potential fiscal impacts of a proposed subdivision development warrant careful analysis, even though the developer may be required to pay the costs of all on-site improvement, costs that the developer will pass on to the lot purchasers.

Because land subdivision affects a broad spectrum of interests, and the welfare of the community in many respects, the public regulation of land subdivision has become widely accepted as a function of municipal, county, and state government. Land subdivision regulation is an exercise of control by the community over the conversion of land into building sites. It is through such regulation that the public interest in land subdivision is expressed and directed. Land subdivision regulation is intended to accomplish the following seven purposes:

1. Ensure that proposed land subdivision will fit harmoniously into the existing land-use pattern, and will serve to implement the community comprehensive plan for the physical development of the community.

2. Ensure that adequate provision is made for the necessary and planned neighborhood and community facilities, including parks, access ways to navigable waters, schools, and shopping areas, so that a healthy, attractive, and efficient urban environment results.

3. Ensure that sound standards for the development of land are met with particular attention to such factors as street layouts, widths, and grades; vehicular and pedestrian circulation; park and open space requirements; block configurations and lot sizes; and street, utility, stormwater management, and transit improvements.

4. Provide a basis for clear and accurate property boundary line, demarcations and records. This was the sole purpose of many original state subdivision control enabling acts dating back to the early nineteenth century.

5. Ensure the fiscal stability of the community, minimizing the capital, operating and maintenance costs of public facilities and services, and protecting against the development over time of blighted areas.

6. Promote the public health safety and general welfare.

7. Balance private property rights against the need to protect and preserve the public health safety and general welfare.

The community zoning ordinance relates to the type of building development that can be placed on the land, whereas the land subdivision control ordinance relates to the way in which land is divided and made ready for building development. The purpose of a land subdivision control ordinance should be to ensure compliance with at least minimum standards for sound development, and to prevent further occurrence of the abuses in land development that have occurred in the past.

Because of its importance to sound community development, subdivision design and development is highly regulated. State statutes provide the enabling authority for the exercise of subdivision control at the county and municipal levels. State statutes and administrative codes will usually also provide for the review and approval of proposed land subdivision plats by such state agencies as the departments of transportation and natural resources. State administrative codes will often specify in great detail the survey data that must be shown on final subdivision plats, as well as the levels of precision and accuracy required for the surveys and survey computations on which the plats are based. County and municipal ordinances will usually specify in great detail design standards and required improvements such as of streets, sanitary sewers, water mains, stormwa-ter management facilities, and street trees, lighting, and signing. Approved plats must be recorded with the county register of deeds in order to permit reference to plats in the conveyance of title to real properties, to levy real property taxes, and to prevent fraud. State statutes normally require that the plats be prepared by registered land surveyors, and the surveyors are usually made responsible for the compliance with subdivision control regulations.

Subdivision Design

Land subdivision design is an art requiring a high degree of technical skill and full realization of the importance of the design of the various interests involved and affected. Good land subdivision design requires imagination and creativity, as well as adherence to sound principles of land planning and engineering practices and to sound design and development standards. For these reasons, public regulation alone is no guarantee of good land subdivision design. For large subdivisions, a design team consisting of a land planner, a landscape architect, a civil engineer, and a land surveyor should be employed. In undertaking a subdivision design, a designer, or design team, may face one of three situations that will determine the manner in which the design must be approached:

1. The land proposed to be subdivided is located within a community that has not prepared and adopted a comprehensive plan.

2. The land proposed to be subdivided is located within a community that has prepared and adopted a comprehensive plan, but that plan does not include, as a component, detailed neighborhood unit development plans or platting layouts.

3. The land proposed to be subdivided is located within the community that has prepared and adopted a comprehensive plan, and that plan includes detailed neighborhood unit development plans or platting layouts.

In the case where a community has not prepared and adopted a comprehensive plan, the designer or design team will have no overall planning framework within which to work. Accordingly, great skill and experience are required, together with intimate knowledge of the principles and practices governing good subdivision design. Substantially greater effort will be required on the part of the designer, or design team, than would be the case if sound local planning had provided a framework for the design process.

In the case where the land proposed to be subdivided is located within the community that has prepared and adopted a comprehensive plan, but has not prepared and adopted detailed neighborhood unit development plans or platting layouts as an element of that plan, the adopted community plan will provide a broad, invaluable guidance to the designer, or design team. The comprehensive plan should contain specific recommendations relative to such matters important to good subdivision design as the location and width of arterial streets, the generalized location of needed school and park sites; and the generalized location and configuration of needed drainage ways and stormwater retention or detention areas. The plan should also provide much of the information essential to good design, including current aerial photography, large-scale topographic and cadastral maps; detailed soil maps with attendant use interpretations; definitive information on the location and configuration of flood hazard areas; and on the location and configuration of such elements of the natural resources base as wetlands, woodlands, and wildlife habitat areas. Importantly, the comprehensive plan should specify the type and densities of land uses to be accommodated within the proposed subdivision; the densities for residential use usually being expressed as the maximum number of dwelling units permitted per gross acre. In this case, the designer, or design team, can focus on the creation of an efficient and attractive street, block, and lot layout, and on the creation of a unified design for the proposed subdivision.

In the case where the land proposed to be subdivided lies within a community that has adopted a comprehensive plan that includes detailed neighborhood development plans or platting layouts, the local unit of government concerned will have provided not only data concerning the types of and entities of land use to be accommodated on the land concerned, but proposed specific locations for neighborhood schools, parks and drainage ways, together with a specific layout for collector and land access, as well as arterial, streets. In this case, the designer or design team will be responsible for reviewing the design provided in the comprehensive plan, for proposing design improvement to that plan, and for ensuring the unity of design with the subdivision itself. In this case, the adopted neighborhood unit plans or platting layouts should be viewed as points of departure for the design of the subdivisions of individual tracts of land included within the neighborhood units. The adopted neighborhood unit plan should not unduly constrain the designer, or design team, in seeking more creative or cost-effective approaches to the subdivision design concerned. Changes in the adopted neighborhood unit development plan may be particularly warranted if that plan no longer adequately reflects current market conditions.

Figure 6.2 depicts a neighborhood unit plan that incorporates sound design principles. It provides, for example, a centrally located neighborhood park in conjunction with a neighborhood school site. The collector street layout is designed to carry traffic into and out of the neighborhood, rather than through it; and neighborhood shopping center having access to the collector and arterial street system is provided. The collector and land access streets are carefully designed to fit the topography of the site in order to minimize grading, and the destruction of existing tree growth, ground cover, and top soil; to facilitate good drainage; and to facilitate the design of gravity drainage sanitary sewers. The street layout facilitates good lot layout; and access to arterial streets is limited. The system of natural drainage ways, together with the street rights-of-way, form a viable major stormwater drainage system. The neighborhood shown is an area slightly larger than one square mile and a development density of about 5,200 persons per square mile, or about eight persons per gross acre. The elementary school would have an enrollment of about 450 children.

It should be noted that the principles underlying the design of the particular neighborhood unit shown predate the recent interest in what has been termed new urbanism design. The new urbanism design is, however, in essence little more than a return to older subdivision designs used in developing the central cities and first-ring suburbs of American cities. The neighborhood unit shown would meet the new urbanism design principles in many respects, such as the provision of neighborhood shopping, park and playground, and school facilities. A new urbanism design would probably favor a higher density of development—perhaps up to about 10,000 persons per square mile—and the promotion of mixed land uses, particularly in the provision of commercial and residential subareas.

Site Selection and Assessment

As in any site planning effort, the land subdivision design process should be preceded by site selection and assessment. Site selection should be determined by market analyses and land availability and value studies, but should be constrained by the recommendations contained in adopted comprehensive plans and in the implementing zoning ordinances. The comprehensive plan should identify the areas recommended for new residential, commercial, industrial, and institutional development within the municipal planning area, including the extraterritorial areas envisioned as being part of the municipal sphere of interest. The comprehensive plan should recommend the placement of new land-use development in time as well as space, while the zoning ordinance, in accordance with the

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