Fresno, California is essentially the kind of a city that is continuously spreading out instead of building up with time. In the past decades, any of the locals can easily observe that the city has been spreading out to the north (e.g., those in the north from the Copper Ave) and east (e.g., those in the southeast from the Fowler Ave). The above-mentioned edge cities can be even found along Highway 41 toward Madera County, such as the new built Tesoro Viejo neighborhood, although there are some renewed apartments with a higher density structure found in the downtown area. To help Fresno move toward sustainability requires the understanding of the effects of varied transportation investments and land-use restrictions, such as the provision of public transit and bike lanes, high density zoning, and growth boundary. However, this had not been done in the past to provide a research framework to comprehensively evaluate either such a transportation or land-use policy for the promotion of a compact city toward sustainability, and therefore is needed.
To fulfill the gap mentioned above, a gravity model, TELUM, is used to better understand how a transportation or land-use policy can help with the compaction of future developments, while accounting for urban economies and physical limitations in a simulation. TELUM (Transpiration, Economic, and Land-Use Model), developed by Dr. Putman at the University of Pennsylvania, is a widely used integrated interactive software package for evaluating the impacts of transportation improvement projects or land-supply restrictions on population, employment and land uses (Casper et al., 2009). TELUM uses a series of computer sub-models, which are linked to a suite of transportation model, to spatially allocate future population (TELUM-RES), employment (TELUM-EMP), and land uses (LANCON) in the study region based on such inputs as households by income groups, jobs by employment sector, and land consumption, and availability for future growth (Casper et al., 2009). Thus, TELUM is a suitable urban model for exploring to what extent transportation improvement and land-use restriction can help shift the current urban form of Fresno to be a compact one, how much effort in these two planning tools it requires to make the shifting occur, and how long it will take to complete the process.
California State University, Fresno
This study is to solve a longstanding urban planning problem (urban sprawl) through a new method of operating a classic urban gravity model. Urban models have been used to forecast future developments for a city and therefore planners can prepare to provide adequate land uses, transportation and public infrastructure and facilities. Most studies only focused on the forecasting function from these urban models, but neglected a possibility that these urban models can be operated in the reverse direction. For instance, one can easily use an urban model to simulate for what will happen if a high-density zoning policy is implemented in a city. However, this model can be also use to test how strict land-supply restriction should be considered to make a significant change to compact future developments in a relatively small geographical space. This approach can be also employed to other polices, such as transportation investments, to promote a compact city toward sustainability. The idea of compaction as a smart growth approach has been discussed for decades but it is still rare to see a successful case in the real world. The propose research framework can be used in any city to evaluate how a transportation or land-use policy would affect the urban form, how much effort it is required to make a difference, and how long it will take to complete the change. This study not only adds to the literature on urban modeling but also contribute to the practice of smart growth or new urbanism.