GIS Model Comparing the Cost of Sprawl verses New Urbanism
Stewart Mitchell
Rapid population growth in and around Bozeman, Montana is creating land use patterns typically associated with sprawl. The community is struggling to recognize and manage the rising costs of growth while still preserving the traditional quality of life. The project described here outlines how a Geographic Information System (GIS) was used to determine the cost of services for two different development patterns and present the result to stakeholders.
Bozeman’s high quality of life is largely a function of its compact land use patterns, small population, relatively mixed land uses, and proximity to resource amenities. It is accepted in parts of the community that rapid unplanned growth is having negative impacts on the quality of life. Current planning and zoning regulations permit only low-density, segregated land use developments. The recent influx of migrants has created large areas of low-density development away from the town center, thus increasing the amount of traffic and demand for municipal services.
The two development patterns compared in the study
are commonly known as “new urbanism” and “sprawl” (figure 1). New urbanism seeks to recreate the desirable
elements of typical pre-war, pre-automobile, pedestrian-based development
patterns with accommodations for the modern world. The basic characteristics of new urbanism are higher densities,
large percentages of public open space, and mixed non-conflicting land
uses. Sprawl development consists of
single family detached homes on individual lots with other land use types
segregated to other areas. New urbanism represents traditional land use
patterns in Bozeman while sprawl is typical of most development occurring in
the last decade.
The study area is a recently annexed and undeveloped
385 acre parcel on the western edge of Bozeman. This site is currently platted for single family detached housing
on half acre lots. Each conceptual
development was designed to sit on this same footprint of land. The study concept was created by myself and
Paul Cartwright of the Montana Department of Environmental Quality and the
environment. The cost data for services
and general development layouts were provided by the City of Bozeman
Engineering and Planning Departments.
The tax revenue data was supplied by The Gallatin County Assessors
Office.
ArcView (Esri) and the SmartPlaces (EPRI) extension
were used to compare the cost of services and the amount of tax revenue
generated by each development and to illustrate the modeling method. The municipal services include installation
cost for water, sewer, roads, electric, gas, and the annual maintenance cost
for public open space. The average tax
revenue for each land use type was used to calculate the overall tax revenue for
each development. Five generalized land
use types were used in the model
● Commercial-Residential:
Represents a typical “main street business”
with commercial use on street level and residential or commercial use on
upper levels.
● Multi-Family: Represents between 2
and 12 unit apartment buildings. Each
lot of this type is quantified as having one 6 unit building.
● Single Family Detached: Represents
one single family residence on an individual lot.
●Single Family Attached: Represents one
single family attached residence on one lot. In reality, this could be four
townhouses or four condominiums on the area occupied by four lots.
● Public Open Space: Represents parks,
ball fields, trails and playgrounds.
Using a GIS with SmartPlaces to directly compare two well-defined development patterns returns tangible and defensible results. It also fulfilled a main goal of the study, keeping the methodology simple enough to be understood by all stakeholders. Although the project required large amounts of data compilation, it is relatively simple from a GIS perspective. The model can be thought of as a spatial spreadsheet accounting for differences in cost among the many different spatial and non-spatial attributes associated with of each the development patterns. SmartPlaces provides an intuitive graphical interface, the Radix, that represents the analysis method and the actual functions performed by ArcView (Figure 2). For example, the linear cost of a feature is stored in a cost field in the attribute table. SmartPlaces represent each field graphically and sums the values for the cost field within each theme simultaneously, generating a “report card” for each development scenario (Figure 2). The report cards for both developments are summarized in table 1.
Table:1
Results
|
Sprawl
|
New Urbanism |
Total Cost of Services
|
$13,609,968 |
$15,499,501 |
|
Cost of Services per Household |
$15,258 |
$10,666 |
|
Total Tax Revenue |
$1,784,000 |
$2,555,760 |
|
Tax Revenue per Household |
$2,000 |
$1,759 |
|
Households |
892 |
1453 |
|
Dwelling Units per Total Area (acres) |
2.3 |
3.8 |
|
Acres of Public Open Space |
51 |
153 |
Although
SmartPlaces is capable of representing the decision making processes and a
whole host of statistical analysis, using the radix to illustrate the data and
calculations proved an excellent method of explaining the workings and results
of the model.
In this study the new urbanist development
was shown to have a lower cost of services per-household while generating more
total annual tax revenue than the sprawl development. Due to the higher density in the new urbanist development, it
offers a more cost effective and efficient land use pattern for the Gallatin
Valley than sprawl. The sprawl development
pattern would require 63% more land to accommodate the projected population
increase of the next 20 years in the Bozeman area.
The model proved to be an effective tool for
assessing the costs of services of each development. It offers a degree of
objectivity in the current debate over alternatives for growth management
issues through its ability to quickly demonstrate the calculations involved in
the comparison process. This study
demonstrates that the adoption of a different land use paradigm can be
economically beneficial and consume less land resources.
Stewart Mitchell
GIS Specialist
DTM Consulting
211 N. Grand Ave
Bozeman, MT
59715
www.dtmgis.com