How to subdivide land without promoting sprawl

Subdivision is by far the most overlooked component of municipal land development. The imprint on the land from subdivision is practically irreversible — while the buildings change over time, streets and open space last for generations and often for centuries.

Subdivision shapes the urban realm by creating streets, blocks, and open spaces, and sets the tone for development that will follow because the layout and quality of streets greatly influence the future built environment. Yet in most cases, public agency review of land subdivision is essentially a routine bureaucratic function that occurs without any place-making oversight.

Our ability to create distinctive and livable places is an antidote to uniform and unresponsive sprawling subdivisions. Subdivision standards must address spatial design of places and be carefully integrated within the regulatory framework of zoning, public works, and fire standards. Form-based codes can provide a unified development code included new subdivision standards that can bring about a specific type of place desired by the community.

History of subdivision in North America

In 1573, King Phillip II of Spain put in place guidelines for Spanish colonists on how to create and expand towns in Spanish America. These guidelines, known as The Laws of The Indies, addressed spatial integration of towns with local geography, climate, and traditions – items that are seldom addressed by contemporary subdivision regulations.

The westward expansion of the railroads lines in the mid-nineteenth century led to the creation of many town settlements with a rectilinear gridiron plan. “Standardized town plats were often used repeatedly — in Illinois, the same plat map was used 33 times,” note Michael Southworth and Eran Ben-Joseph in their book Streets and the Shaping of Towns and Cities.

In 1930s, the Federal Housing Administration (FHA) developed minimum subdivision standards and required compliance for homes securing federal insured mortgages. City planning commissions often adopted and implemented these FHA standards to regulate subdivisions. Over the years, these regulations have been tweaked to capture emerging views of best practices from disparate disciplines of traffic engineering, public safety, and public works, with little questioning or evaluation as to their effect of these practices on place-making.

In the 1920s, the Standard City Planning Act called for a stronger tie between the master plan, zoning, and subdivision standards, but the three never really came together to facilitate great places, on the contrary ended up producing sprawl.

Problems with contemporary subdivision standards

Contemporary subdivision regulations produce sprawl by default. Products of conventional

subdivisions are residential subdivisions with curved roads and cul-de-sacs, commercial strip center, malls, and office parks. For instance, suburban sprawl is created by subdivision standards that limit access, disallow alleys and on-street parking, and mandate street designs that are vehicle dominant. Such standards enable greenfield sprawl and inhibit urban infill or redevelopment.

“The art of urban planning – of designing a hierarchy of public spaces that reinforce civic pride — is missing from conventional subdivision standards,” says Joe Kohl, principal with the town planning firm Dover, Kohl and Partners. Engineers and surveyors often prepare subdivision plats; only the very rare engineer or surveyor has any formal or informal training in spatial planning or design. “They simply read and comply with the subdivision regulations and make up the rest as they go along, based on what their client asks for, what they see others doing,” notes Paul Crabtree, P.E., President of Crabtree Group, Inc.

The staple of conventional subdivision is the uniform large-lot requirement.  This one standard has destroyed vast amounts of rural and agricultural land and allowed cities to legally exclude low-income residents who are priced out of the market.

Form-based codes address subdivision standards

Conventional subdivision regulations are seldom tied to a specific vision of a place.  Subdivision approvals are considered ministerial actions by governmental staff.  If the lot and street widths, and open space meet the minimum standards then a subdivision typically must be approved.  Baseline subdivision regulations are often banal and boiled down to minimum regulations that produce similar looking places with no regard to local context and character. “In Iowa, streets are wide to accommodate swales for snow storage; the same street standard in southern states is meaningless,” says Dan Sloane, Esq. of McGuire Woods LLP.

The deficiencies of subdivision standards are one reason why planners are now looking at form-based codes. The block, street, and open space requirements of form-based codes are drafted to work together with building types to create a specific urban place desired by the community.

The thesis of form-based coding is the same as that for more conventional zoning and subdivision standards: a comprehensive or general plan spells out how the community wants to develop, and regulations then carry out that plan. The difference is that a form-based approach develops an explicit physical vision and then carries out that vision through an integrated implementation of prescriptive subdivision and zoning-type regulations.

Form-based codes are applied through a specific “regulating plan,” a map that applies the new standards to specific blocks and neighborhoods. Specific building envelope standards, and public space standards are clearly defined.  The function and location of streets and their relationship with buildings and open spaces are shown on the regulating plan. Building heights, the placement of buildings on a lot, and uses are then further defined by means of building envelope standards. Typical street sections specify the cartway widths, curb radii, sidewalk and tree planting area dimensions, on-street parking configurations, and other amenities. Architectural standards often regulate important public elements of the facade.

Kaizer Rangwala, AICP, CEcD, CNU-A, is the founding principal of Rangwala Associates, a town-planning firm that practices the principles of smart growth and walkable urbanism.