This study measures sprawl in multiple dimensions and investigates its impact on an array of transportation-related outcomes. For most outcomes, sprawling regions perform less well than compact ones.
This is true of everything from transit use to traffic fatalities. The exceptions are average commute time and annual traffic delay per capital, which do not clearly favor compactness over sprawl.
The main limitation of this study has to do with the data it uses.
By necessity, the study uses highly aggregate data from a variety of sources that are not always consistent as to the area under study and time period. They are simply the best data available from national sources with sufficient breadth to provide a panoramic view of sprawl in the United States. Results will have to be validated through follow-up work of a more focused nature.