Table of ContentsIntroduction
Suburban sprawl - it conjures up images of seemingly endless hours in traffic jams, housing construction at every turn, and environmental degradation. People want spacious homes and ample land, but they also want fewer traffic woes, clean water and air, adequate sewers, and protection of open space. It is difficult to address all of these issues in a growing area. This is an acute problem in the counties of Middlesex, Somerset, and Mercer in central New Jersey, because they comprise one of the country's fastest growing regions and their growth pattern has led to widespread suburban sprawl.
Over the last twenty years, 61% of the region's open land was developed whereas its population only grew by 21%; this means that each person is consuming more and more land. If this trend continues, the state's projected population is expected to consume all available land in the region before 2020.
How do regional planners tackle this issue? They try to concentrate growth in currently developed areas, minimize expansion into undeveloped areas, and maintain open space. Such efforts are often called "Smart Growth" planning. The Regional Planning Partnership (RPP), a New Jersey non-profit group, decided to develop a land use/transportation plan, Vision 2050, that coordinates Smart Growth land use scenarios with various modes of transportation. RPP found that traffic congestion motivates people to consider land use changes more than any other local planning issue, so it based Vision 2050 on the idea that if you want alternative transportation options, you have to change the land use.
This requires altering the region's zoning (local regulations governing land use.PP developed the GOZ (Goal-Oriented Zoning) computer model to compare the results of development under traditional zoning laws versus Smart Growth with new zoning categories based on Vision 2050. GOZ quantifies the impacts of both types of growth on infrastructure (roads, water supply, etc.), natural resources, and public sector costs. GOZ's unique strength is that it is based on zoning, an issue that virtually every uses to control land use. It quantifies the ultimate effects of zoning build-out (maximum allowable development) and thus helps to focus discussion on the advantages of Smart Growth alternatives. RPP hopes that GOZ will be used as a catalyst for changing the unintended consequences of current zoning practices.
GOZ uses computerized mapping to capture land use data (existing zoning, municipal boundaries, and zoning by composite index), infrastructure systems (roads & transit, traffic, water & sewer service areas), and natural systems (preserved open space, agricultural and forested land, wetlands). It identifies the amount of land that is available for development per zone and then calculates the maximum number of residential units and non-residential square footage that could be built. These data are then used to calculate the growth in population, additional school children, jobs, traffic, water consumption, air and water pollution, and public capital costs borne by the community.
For example, the build-out, transportation, and environmental impacts calculated by GOZ for existing zoning versus Vision 2050 Smart Growth, are summarized below. In this scenario, public capital costs are estimated to be 10% less with the GOZ alternative.
Table 1 - Comparing Smart Growth and Existing Zoning
Why does GOZ make sense?
Strengths of GOZ
Challenges/Limitations of GOZ
Future Versions of GOZ
The Regional Planning Partnership (RPP) developed the GOZ (Goal-Oriented Zoning) model to address the rapid population growth and the rise in low-density, single-use development ("sprawl") facing central New Jersey. GOZ's most unique attribute is that its methodology and calculations are based on zoning, which most planning models do not incorporate. The model's purpose is to illustrate the impacts of land use decisions under various alternative zoning scenarios, in order to identify priority zoning changes that effectively support Smart Growth. By quantifying the effects of zoning changes, the model sheds light on the effects of Smart Growth. It can then be used as a tool to alter undesirable zoning practices. The model contains data sets for both existing zoning and a smart growth scenario to reveal the possible ramifications of uncontrolled, rapid growth in the region. Users can adjust the assumptions for both options; test alternative land use scenarios and use the model's reporting capabilities to compare the results. The first step involved in creating the model is inputting land use, environmental, and infrastructure data. These data sets include the amount of developed, undeveloped, and constrained land, existing zoning, and twelve categories of composite zoning (e.g., business/ commercial, mixed use, conservation, residential). It then calculates impacts in five major areas: traffic, water consumption, water pollution, air pollution, and public capital costs.
GOZ was designed for planning professionals and it uses terminology, data sets, and GIS technology that are commonly understood by its target audience. It addresses a range of important issues such as transportation and environmental concerns, and is transparent enough for users to easily manipulate the assumptions and conduct additional analyses. The goal of the GOZ modeling effort is to improve planning practice by providing an affordable, accessible, and easy-to-use tool for developing capacity-based plans and zoning ordinances.
The central New Jersey region is one of the fastest growing regions in the country. Comprised of Middlesex, Somerset, and Mercer counties, the region has experienced a 21% increase in population and a 70% increase in employment over the last twenty years. Metropolitan expansion out of New York and Philadelphia combined with the suburbanization trends of the 1980s shifted the economic power to the less densely populated southern half of the state, along U.S. Route 1. According to a recent national real estate survey, Somerset, Middlesex, and Hunterdon (a contiguous central New Jersey region) are the hottest markets in the United States.
Figure 1 - GOZ Study Area in New Jersey
By consuming land at a rate three times the rate of population growth, RPP contends that the population is "spreading out" too quickly. The GOZ (Goal-Oriented Zoning) model was designed to address these issues and shed light on the possible ramifications of uncontrolled, rapid growth in the region.
Definition of the Problem
Effective local planning efforts rely on relationships among infrastructure management, environmental protection, zoning ordinances, and impacts of the land development process. All too often, however, the infrastructure and environmental protection goals do not coincide with zoning and land development, and the consequence is dispersed, low-density development ("sprawl"). The problem can be attributed to a lack of capacity-based planning. The local planning process fails to recognize the demands placed on roadway capacity, water and sewer capacity, and natural resource "carrying capacity." Many master plans are adopted without build-out analysis (the full development of a piece of land based on its specific zoning parameters), traffic impact studies, or other analyses of infrastructure or service needs. Thus, the plans often advocate goals without having the proper information to achieve them. The GOZ model addresses land use and development issues stemming from both current zoning and Smart Growth initiatives. It quantifies the effects of zoning changes, which helps to clarify the impacts of Smart Growth. GOZ's most unique attribute is that its methodology and calculations are based on zoning. The absence of zoning strategies has been a common obstacle in implementing Smart Growth objectives. RPP developed the GOZ model to demonstrate the advantages of Smart Growth, compare it to build-out scenarios, and portray the consequences if Smart Growth is not implemented.
GOZ applies formulas to the existing zoning categories and calculates build-out potential, in order to show a community what the future may look like barring any structured planning efforts. For its Smart Growth option, it uses a data set based on a plan developed by the RPP. After trying to promote mixed-use, compact centers in the past with little success, the organization developed a plan called Vision 2050. In Vision 2050, RPP shifted to a more transportation-based focus because it realized that traffic congestion motivates people to consider land use changes more than any other local planning issue, such as center-based development and open space preservation. This assertion is based on RPP's 30-year planning experience in the region. The RPP looked at maps of the region, picked likely places for future development, designed new zoning categories (e.g., Rural Environs, Center Neighborhood I, Urban CBD), and identified intra-regional transportation linkages. Vision 2050 encompasses 32 municipalities and was designed to be consistent with the state plan. It is based on the idea that if you want alternative transportation options, you have to change the land use.
GOZ is a GIS-based computer model that was designed to test the impact of development under traditional zoning laws and to compare it to alternative growth scenarios using new zoning categories. It quantifies the impacts of growth on infrastructure, natural resources, and costs through four scenarios: 1) build-out of existing zoning; 2) variations on existing zoning; 3) Smart Growth alternatives based on Vision 2050; and 4) variations on Smart Growth zoning. It was designed to help planning practitioners with the master planning process. Using GOZ, local planners can test decisions before making them.
The goal of the GOZ modeling effort is to improve planning practice by providing an affordable, accessible, and easy-to-use tool for developing capacity-based plans and zoning ordinances. It can also perform analyses based on watershed management areas, which is a new designation introduced by the New Jersey Department of Environmental Protection. Target audiences are those involved in the planning process such as local planners, developers, landowners, non-profit organizations, and citizen groups. By identifying the magnitude of impacts, GOZ provides a quantifiable basis for comparing alternative scenarios.
The developers of GOZ hope that its use will result in more thoughtful planning and land use decisions being made, leading to better outcomes on the ground- less congestion, less pollution, more open space preservation, and more redevelopment.
GOZ is a computer program that calculates the impacts of build-out under alternative zoning scenarios. It organizes land use, infrastructure, and environmental mapping and data for the 32-municipality study region. The model performs its analysis using GIS technology (ESRI's ArcView 3.1 or higher) and accepted impact assessment indicators, formulae, and multipliers. The program uses the amount of developable land within each zoning classification to calculate the type and amount of development that would occur under build-out. Both residential and non-residential development is included. Developable land is the basis for the model's impact calculations and is defined as all land that is neither constrained nor already developed.
Based upon the amount of development entered into the model, GOZ calculates various impacts upon infrastructure, the environment, and public costs. This allows the user to:
GOZ does not assign its impacts directly to particular systems, e.g., the model does not conduct capacity analysis. However, with the list of impacts that GOZ provides, the user can undertake a capacity-based planning off-model.
The GOZ modeling process (shown below) starts by identifying the amount of developable land and zones. It then calculates growth in housing units, the population, and number of school children. For non-residential units, it calculates floor area and employment. Finally, these data are used to calculate additional impacts, correlated by zoning type.
Figure 2 - GOZ Model Structure
These steps are described in more detail below:
Data inputs and mapping
The region is mapped and land is classified into: developed (land with structures on it), undeveloped (farmland, parkland, or other vacant land), and constrained (land that cannot be developed for environmental or other reasons, e.g., floodplains, wetlands, and preserved parks). The model includes the existing zoning maps for all 32 municipalities, and information on each zoning district such as allowable density of residential units and allowable square footage of building space.
Evaluating different scenarios
GOZ includes two "prepackaged" zoning scenarios: existing zoning and the RPP's Smart Growth alternative zoning. Impacts from build-out are available for each scenario. For each area in question, the model examines two land components: 1) developable land; and 2) currently developed land. In the first case, GOZ applies zoning parameters to calculate build-out on land that is currently unused. In the second case, the model allows the user to apply a redevelopment factor (0, 10%, 25%, 50%, 75%, or 100%). This represents the extent to which currently developed land within a center will be re-built under the chosen scenario. For example, if the user chooses a redevelopment factor of 0, GOZ assumes that the build-out analysis will only focus on the developable land. Conversely, with a 50% redevelopment factor, there will be full build-out on the developable land plus 50% of the currently developed land would be redeveloped according to the chosen neighborhood type.
In addition to these standard options, users can create their own zoning scenarios by: modifying the existing zoning, drawing their own Smart Growth scenario, or manipulating the assumptions and factors used in the impact calculations. For example, when creating a new center, the user can mark the center boundary in three ways: by adding a transit core center (a circle with a 2,000-foot radius), by drawing a new polygon, or by capturing an existing polygon from another data layer.
Calculating developable land and the amount of additional development
The amount of developable land generated by Step 1 is used as the basis for the model's calculations. It is calculated by subtracting constrained land from undeveloped land. Once the amount of developable land and applicable zoning characteristics are determined, GOZ calculates the total number of housing units or square footage of non-residential space that could be legally built on the developable land. In doing so, the model calculates the maximum additional development allowed (build-out), for each zone, by municipality, and for the entire region.
Calculating impacts from the additional development
Based on the results from Step 3, GOZ then calculates impacts on infrastructure, natural resources, and costs. These calculations are performed using multipliers derived from published research and industry standards. It is important to note that impacts are calculated for incremental growth between current conditions and full build-out.
Impacts include: population and number of school children, number of jobs, vehicle trips and vehicle miles traveled, water and sewer demand, water and air pollution, and the capital costs of building schools, water/ sewer facilities, and roads.
Reporting the results
The strength of the model's output is its reporting capability. The user can generate reports to compare alternative scenarios or compare results against other models. It uses Seagate Crystal Reports software to produce reports that describe the model output for the new development occurring under build-out (Step 3) and the impacts from Step 4. Users can generate reports for a municipality, county, watershed, or for the entire region. The reports can be printed, displayed on-screen, or exported to a spreadsheet program. Users can also print maps showing the borders of zoning districts.
Relationship to and/or Incorporation of Travel Models
GOZ is a land use model that generates infrastructure outputs including vehicle trips and vehicle miles traveled (VMT). Since the model was based on the assumption that increased traffic congestion is a public motivator, these can be some of the model's more influential outputs. Vehicle trips are produced based on the types of dwelling units and non-residential development chosen and VMTs are calculated by multiplying the daily vehicle trips by an average vehicle trip length factor.
GOZ, however, is somewhat constrained when working with other models. Its data are based on zoning units whereas New Jersey data are based on Census tract data. Census data can be re-aggregated into transportation area zones (TAZs), but zoning units cannot. Although this limits the range of "plug and play" options, GOZ results can be used to inform scenarios used in other models; vehicle trips and VMT data are applicable to most transportation modeling efforts.
Data Inputs and Outputs
The GOZ model relies on data and maps available from state and federal agencies as well as data and maps created by the RPP. It utilizes land use, environmental, and infrastructure data related to the study region to generate the amount of developable land (the primary basis for the model's calculations). Data inputs used are:
Twelve categories of composite zoning:
Three database tables include all the inputs and factors/multipliers for performing the development impact calculations:
Sources for these multipliers are:
Additional data layers include aerial photography, municipal zoning maps of all 32 municipalities, steep slopes, and roads & transit. Once the developable land is identified and the model calculates the amount and type of development that would occur under build-out, it calculates impacts in the following major areas: traffic, water consumption, water pollution, air pollution, and public capital costs.
Figure 3 - Sample GOZ Report
Specifically, the data outputs are:
The data outputs can then be analyzed and compared through the model's reporting mechanism, which is its most powerful tool. Data are depicted in a way that allows for easy analysis. The software produces two basic types of reports, detailed reports and summary comparison reports. Detailed reports show build-out impacts for each zoning classification in the municipality, county, region, or watershed and are available in three types: units and square feet, impacts and costs, and water demand and pollution calculations.
The summary reports show total calculations for the entire study area and present a side-by-side comparison of projected impacts of alternate zoning scenarios. Several types of summary reports are available: compare existing zoning to smart growth, compare existing zoning to alternative assumptions, compare existing zoning to alternative existing zoning, and compare existing zoning to redevelopment factors.
GOZ reports can illustrate:
GIS and Visualization Components
Figure 4 - Typical GOZ table and map in Arc View
GOZ uses GIS technology (ESRI's ArcView 3.1 or higher) to manage and display spatial information. A custom-written GIS script provides a unique GOZ interface for ArcView and allows a user to manipulate and evaluate data in the study area. Data are displayed in maps and tables, and queries can be formatted for output to Crystal Reports. The GOZ model segments the chosen study area into polygons based on zoning districts, the essential units of analysis.
The GOZ model was designed to allow the user to analyze and compare the ramifications of growth based on existing zoning versus smart growth alternatives. It uses easily understood assumptions to calculate vehicle trips, vehicle miles traveled, water and air pollution, and estimate public capital costs.
Smart Growth/Growth Management
The GOZ model's smart growth scenario is based on the Vision 2050 plan, the Regional Planning Partnership's invention. Vision 2050 uses newly created transportation linkages and zoning categories. For example, the new residential zoning category "Neighborhood Core" has 10 dwelling units per acre whereas the current residential zoning category "High Density" has 6.0-7.9 dwelling units per acre. The idea is that if people want to reduce traffic congestion, they have to incorporate different zoning categories and development densities.
The GOZ model's basic assumptions about development and its impacts are:
The GOZ model's basic assumptions about smart growth are:
Summary of build-out impacts:
Based upon the model's calculations, under existing zoning build-out, the region would gain 198,919 people, 48,395 school-age children, and 964,857 employees. Under the Smart Growth alternative, the region would gain more than 282,000 people (42% more than under existing zoning), 68,795 school-age children (42% more), and more than 660,000 employees (31% less). Although the increases in population and school-aged children under the Smart Growth option present challenges under the current tax structure, GOZ was designed to test alternative scenarios. The Smart Growth option is not presented as a conclusive strategy to address all planning issues.
The GOZ model calculates two transportation impacts, vehicle trips and vehicle miles traveled (VMT). To calculate daily vehicle trips, it applies a unique factor/multiplier based on the type of dwelling unit and non-residential development. These factors are based upon trip generation rates published by the Institute of Transportation Engineers (ITE) and are listed in the following table (ITE, 1995):
Table 2 - Trip Generation Index
The model also applies a "trip reduction" factor for several Smart Growth alternative zones, which reduces the number of vehicle trips generated by new development in these zones. They are obtained from a 1991 RPP study, and they assume that supporting measures such as public transit service, travel demand management programs, improved site design, and changes in personal travel behavior would also be implemented. The following table lists trip reduction factors used in GOZ:
Table 3 - Trip Reduction Factors
GOZ calculates daily VMT by multiplying the daily vehicle trips by an average vehicle trip length factor; the model assumes a 9-mile average trip length for all vehicle trips. This factor was based on the 1990 National Personal Transportation Survey.
Summary of transportation impacts:
Under existing zoning build-out, the daily number of vehicle trips and VMTs would increase by 6.3 million and 56 million, respectively. Under the Smart Growth alternative (based on Vision 2050 inputs), the vehicle trips would increase by only 4 million and VMTs would increase by 36 million (36% less than under existing zoning).
One of the unique features of the GOZ model is its conversion of land use data, multipliers, and formulae to air and water pollution indicators. It calculates the level of air pollution generated from motor vehicle emissions for three types of pollutants: non-methane hydrocarbons (NMHC), carbon monoxide (CO), and nitrogen oxides (NOx). Units are in pounds per year. To quantify the air pollution impacts, GOZ applies the following mobile source emissions factors from the U.S. Environmental Protection Agency to the VMT data:
Table 4 - Pollutant Generation Factors
Summary of air pollution impacts:
Under existing zoning build-out, the daily number of VMTs would increase by more than 56 million, and air pollutant levels would increase accordingly. Under the Smart Growth alternative (based on Vision 2050 inputs), VMTs only increase by 36 million, and air pollution would increase at a rate 36% less than under existing zoning build-out.
Water pollution calculations are based on the amount of impervious surface projected for each zone under build-out. GOZ uses the amount of impervious surface to calculate the level of non-point water pollution for five pollutant types: phosphorus, nitrogen, biological oxygen demand (BOD), zinc, and lead. Units are in pounds per year. The model applies factors derived from a 1994 New Jersey Department of Environmental Protection manual to calculate the amount of impervious surface and pollutant levels for the different residential and non-residential zones.
Summary of water pollution impacts:
Under existing zoning build-out, the amount of impervious surface would increase by 23,349 acres and water pollution levels would increase accordingly. Under the Smart Growth alternative (based on Vision 2050 inputs), impervious surface would increase by only 13,652 acres (42% less than under existing zoning) and water pollution levels would decrease by more than 50% compared to existing zoning build-out.
The GOZ model calculates public capital costs for residential development only. It uses the number of dwelling units per zoning classification and calculates public capital costs for schools, roads, and utilities (water and sewer). The factors are taken from a 1974 report by the Real Estate Research Corporation and were adjusted by the Consumer Price Index to convert them to 1999 dollars. Examples of public capital cost factors (in costs per unit) for various development types are listed below:
Table 5 - Public Capital Cost Factors
Summary of public capital costs:
According to the model's calculations, the public capital costs per new dwelling unit would be 10% less under the smart growth alternative than under existing zoning build-out.
Ease of Use/Replicability
Although GOZ was designed to address a specific situation in central New Jersey, any professional engaged in local and regional planning efforts could find it valuable. It uses zoning as its foundation, which is common in the industry; most planners have to consider current zoning in their analyses. Since the data were obtained mainly from state and federal agencies, the terminology and data sets are publicly available and already familiar to the target audience, as the use of readily available data reduces the learning curve and improves the model's usability. Assumptions used in GOZ were designed to be as transparent as possible, thus allowing them to be analyzed and adjusted as needed.
The use of GIS technology on a PC platform, particularly ArcView, is common to many planning agencies. This limits the need to purchase expensive new software and hardware. The desktop aspect of the model and its graphical and side-by-side reporting capabilities make GOZ a tool that can be easily used in a typical planning office to test alternative "if-then" scenarios. A potential hurdle is in manipulating and aggregating the zoning classifications. Correlating the data and digitizing the maps generated by the GOZ model can be very labor-intensive and cumbersome. This lack of a common zoning scheme can limit the model's replicability.
Strengths of GOZ
The GOZ model has several unique strengths:
Challenges/Limitations to GOZ
There are also several challenges and limitations to using the GOZ model:
RPP has outlined the following goals for the future of the GOZ model:
Build-out - the full development of a piece of land based on its specific zoning parameters.
Capacity-based Plan - a planning method that incorporates the demands placed on roadway capacity, water and sewer capacity, and natural resource carrying capacity.
Carrying Capacity - usually refers to the natural environment; it is the maximum population or activity level that can be supported indefinitely in a defined habitat or ecosystem without permanently impairing the productivity of that habitat.
Constrained Land - land that cannot be developed for environmental or other reasons (e.g., floodplains, wetlands, preserved parks).
Developable Land - all land that is neither constrained nor already developed. It is the basis for the GOZ model's calculations.
ESRI ArcView - a desktop geographic information system and mapping software from the ESRI company that provides data visualization, query, analysis, and integration capabilities along with the ability to create and edit geographic data. Currently, more than 500,000 copies are in use worldwide.
Floor Area Ratio (FAR) - the term used to describe the intensity of development on a unit of land; it is determined by dividing the gross floor area of all buildings on a lot by the area of that lot.
GIS - (Geographic Information Systems) - a computer system that can spatially manage, analyze, and present geographic data tied to a particular location. A GIS combines layers of information about a place and allows the user to create customized maps and analyze patterns and relationships.
Master Plan - a comprehensive blueprint for development. In public planning, the objectives are to identify public need and suggest ways to meet these needs through the most rational and efficient expenditure of public funds.
Redevelopment Factor - the extent to which currently developed land within a "center neighborhood" will be redeveloped under the chosen scenario. GOZ allows the user to enter five redevelopment factors: 0%, 10%, 25%, 75%, and 100%. For example, if the user chooses a redevelopment factor of 0, GOZ assumes that the build-out analysis will only focus on the developable land. With a 25% redevelopment factor, there will be full build-out on the developable land plus 25% of the currently developed land would be redeveloped according to the chosen neighborhood type.
Smart Growth - a planning policy that addresses sprawl by concentrating growth in currently developed areas and increasing the use of alternative modes of transportation. It is aimed at minimizing haphazard development, preserving open space, and reducing traffic congestion, while maintaining property values and economic activity.
Sprawl - low-density development, associated with suburbanization, with higher than average amounts of land per capita. It can lead to traffic congestion, reduction of open space, environmental degradation, and long commutes.
Transportation Analysis Zone (TAZ) - the smallest geographically designated area for analysis of transportation activity.
Vehicle Miles Traveled (VMT) - the amount of vehicle travel on a designated set of roadways multiplied by the total mileage of those roadways.
Vision 2050 - a Smart Growth zoning plan with a 50-year vision for the central New Jersey region developed by the Regional Planning Partnership. It uses an intra-regional transit system and focuses growth in selected centers to build growth capacity, increase property value, and reduce traffic congestion.
Zoning - the division of land into different types of uses to avoid nuisances and promote healthy and orderly development.
Mansnerus, Laura, 2000,"Where the Money Is"The New York Times, March 12.
Potash, Jennifer, 1999, "Future Shock: No Place Left to Grow in 20 Years," The Princeton Packet, April 27.
The Regional Planning Partnership, 2000, Goal Oriented Zoning (GOZTM) Model Summary of Impact Calculation Methodology, Draft, September.
The Regional Planning Partnership, 2000, Goal Oriented Zoning (GOZTM) Model: User's Guide, November.
The Regional Planning Partnership, 2000, "GOZTM: A Decision Support Tool for Local Planning," Draft, September.
The Regional Planning Partnership, "Introduction to the GOZTM Model (Goal-Oriented Zoning)," Powerpoint Presentation.
Contact: Planning Partners, Princeton, NJ (609-452-1717 or www.planningpartners.org/aboutus.shtml/)