Case Study:

Envision Utah

Conclusions

Strengths

Overall Approach

The Envision Utah technical analysis illustrates methods for testing a range of impacts of regional transportation and land use scenarios. In one sense, the analysis is integrated as it relies on a common underlying GIS data structure and land use scenario analysis. For areas that are not ready to undertake an effort of the same scale, however, individual model elements could be adopted depending upon locally available data and assessment needs.

The land use, transportation, air quality, and water supply/demand assessments were conducted through a collaborative process among a number of state and local agencies. The Envision Utah analysis shows the benefits of developing a common set of tools and databases. In addition, beyond the technical analysis components, Envision Utah illustrates the value of an extensive outreach campaign to educate and obtain feedback from local officials, developers, and the public. This campaign has resulted in the framing of realistic scenarios and the development of strategies that are potentially feasible both from a political and a market standpoint.

GIS Fundamentals

GIS data management and analysis techniques greatly facilitated the Envision Utah analysis. In particular:

• The use of a GIS raster environment to analyze data, while requiring technical expertise in GIS, made the analysis process more efficient and allowed a finer level of spatial detail. The creation of the scenarios as a fine-celled grid of data allowed a great deal of evaluation to be based on a consistent data representation.
• The Envision Utah process also resulted in an abundance of data with broad utility for other purposes. The process produced an accurate regionwide inventory of existing land use of great utility for local governments and private developers alike. The grids representing future development currently contain only population and job data, but have the potential to carry much more information. Future data might include lot coverage, paved area, fiscal impact, service demand, and any other parameter that can be described in a geographic form and tied to a small incremental unit.
• An example of the utility for raster-based data for transportation modeling is that land use factors such as density and mix could be developed at the sub-TAZ level to more accurately represent clustered development around rail transit stations or other transit nodes.

Land Use Analysis

• The land use analysis for the Quality Growth Strategy was based on a market-driven forecast of housing demand by type, but also made extensive use of infill and reuse development and mixed use/walkable development patterns. The housing market analysis helped to show what could realistically be achieved in the region, given demographic trends and consumer preferences. At the same time, the strategy development process showed that market trends could be accommodated while significantly reducing consumption of new land and related infrastructure costs, and increasing the range of available transportation options.
• The scenarios and quality growth strategies were developed with extensive input from the public and local officials; as a result, they are likely to be realistic and implementable.

Transportation And Air Quality

• The existing travel models were modified to incorporate factors that influence bicycling and walking, increasing their sensitivity to land use and urban design strategy elements.
• The simplified air quality planning model, QMOD, allows the surface winds to move the pollutants from cell to cell within the domain. As a result, a better characterization of pollution distribution can be obtained than if one were to simply disaggregate pollutants as a daily average across the domain, or by the location of their production. The measures of population exposure produced by QMOD are therefore a reasonable starting point for planning if the time and resources to run a full-scale regional airshed model are not available.
• The SPARTACUS case study provides an example of a similar emissions dispersion model. In this case study, the model was used in conjunction with population data to compare emissions exposure among socioeconomic groups.

Infrastructure And Water

• The infrastructure cost models developed for the Envision Utah analysis are among the most sophisticated in the U.S. The on-site cost model was based on an engineering analysis to estimate transportation and other infrastructure costs as a function of development type, density, and location (infill, redevelopment, or new development). This approach provides a more generic and consistent assessment than the use of empirical cost data from existing developments, which can show considerable site-to-site variations depending on local conditions. A similar cost model is being developed for infrastructure at the municipal level.
• The infrastructure cost models are also proving their utility beyond the Envision Utah study. Developers and engineering firms are using the on-site cost model to estimate the costs associated with new developments. The off-site model under development will be made available to municipalities for use in capital costing and programming for comprehensive plans. Adoption of the models to other parts of the country would require consideration of local design standards and practices.
• The water supply/demand model was useful for estimating how water use varied according to residential development patterns (in particular average lot sizes), as well as evaluating the effectiveness of conservation measures. This type of model could be useful in many areas of the country where limited water supplies are a concern. Local calibration of such a model would be necessary, however, to reflect local climatic and water supply conditions.

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