Burchell et al. (2002) produce comprehensive estimates of the various costs of sprawl in 2025 by developing scenarios of controlled growth and uncontrolled growth (business-as-usual sprawl) and then comparing the differences. One component of the cost of sprawl estimated in this study involves the extra travel costs associated with increased travel in spread-out areas, which are based on VMT estimates for the above two scenarios.
The changes in land development in the study’s controlled-growth scenario are complex, which makes it difficult to compare this study with others. Controlled growth cuts sprawl in all nonurban counties by 25 percent compared with their historic trends. For intracounty sprawl, growth is directed toward more urbanized development within the county by increasing the density of this development by 20 percent. Shifting growth by 2025 from sprawling to controlled-growth counties moves 11 percent of new housing (2.6 million households) and 6 percent of jobs (3.1 million jobs).
To estimate travel effects, Burchell et al. estimate a regression model that predicts personal miles of travel as a function of development type (urban, suburban, exurban, rural), income, gender, and household size. Separate models are developed for personally owned vehicles and transit. The models are calibrated by using individual data from the 1995 Nationwide Personal Transportation Survey, but the variables describing the built environment of households are limited, and there is no control for self-selection. (Perhaps as a result, these models explain a small share of the overall variance in the data: the models have an adjusted R2 of about 0.06.) The models predict that shifting residences and jobs from the sprawl to the controlled-growth scenario would reduce person miles of travel by about 4 percent overall. The 4 percent reduction results from combining a 5 percent reduction in travel in personally owned vehicles with a 19 percent increase in travel by transit by 2025.
In a more recent study entitled Growing Cooler, Ewing et al. (2007) develop an estimate of the amount of CO2 that could be reduced by encouraging much greater compact development between 2005 and