The Vision California modeling exercise, however meticulous in its calculation methods, still relies on a slate of assumptions that call for some vigilant critiques. Calthorpe & Associates, which devised Vision California based on previous work, have stated elsewhere that the key to the global warming crisis lies in curbing "sprawl," that pejorative term for low-density suburban development. To the extent that a large lot, single-family home with a multi-car garage represents a choice, it is in Calthorpe's view neither a preferable nor sustainable one.

To gain traction in the public consciousness, the rationale for a smart growth alternative is always carefully constructed around the public policy issue du jour. Recently, it has been about global warming. Now a plethora of research linking sprawl to the obesity crisis has provided additional ammunition to the smart growth cause, as have the economic and housing market crises. The report's greener scenarios may indeed present a multi-benefit package that can be justified on many policy grounds, but the ubiquity of smart growth as a solution to every environmental or social crisis has had the effect of diluting its intellectual credibility. When it is applied generically, smart growth becomes less an inventive response to specific problems and more of a fixed idea.

The Vision California "Rapid Fire" model is intended to be used by localities as they see fit. Even so, to label the development scenarios in Vision California as "options" – and to imply that ever family across the state will be $6,500 richer for them – is misleading on another level, as if land use planning in California were not an utterly decentralized affair, resistant to orchestrated regional efforts. Judging from the recent defeat of California Senate Bill 1445, which would have added a mere $1 to vehicle license registration fees for SB 375 implementation this approach is still a non-starter in California.

Of course, to worry over the political feasibility of a smart growth future is somewhat of an easy target. The lack of an implementation strategy is actually less troubling than some of the assumptions and claims underlying the report itself.

For one, studies on the relationship between household densities and VMT have proven to be inconclusive about the VMT-reduction benefits of "compact" development. Proximity to transit may encourage less driving in some instances, but the rate of vehicle ownership does not necessarily decrease. Though the correlation between car ownership and driving is complex at best, the fact remains that some residents may commute to work via public transportation but still opt to use their cars for leisure and personal trips.

If we dig deeper into report's assumptions, VMT reduction is premised upon "increased transit service and/or new … development" in transit-oriented districts. This, in turn, requires additional infrastructure.  On this point, the report claims that the costs of urban infill (in terms of infrastructure) are significantly less than those of greenfield development, based on the "efficiencies of providing service to higher concentrations of jobs and housing." In reality, the retrofitting of sewer/water systems and the construction of new transit/road systems necessary to accommodate smart growth levels of densification can be extremely expensive.

Moreover, the report focuses only on the capital costs of infrastructure and "does not yet analyze the costs for operations and maintenance." As any urban planner knows, the cumulative ongoing costs to local cities and agencies of operating and maintaining a transit system can very well exceed the original capital costs, even in present value (discounted) terms. This omission in the infrastructure cost comparison skews the results decidedly in favor of urban infill in this initial report. Project officials say that future generations of the Vision California modeling tool will account for these operational costs – and many other factors – so planners should keep a close eye on those numbers.

The Smart Growth coalition has made for some strange bedfellows. Environmentalists are excited about the potential to preserve land and consume less. Developers like the concept of higher densities, as long as market prices can support them. The investment in transportation and infrastructure needed to support TOD is by definition capital-intensive, ensuring a steady supply of lucrative contracts for the construction and financial services sectors, especially with the burgeoning trend toward public-private partnerships.

This alliance has come together in the Vision California report, with the CHSRA leading the charge for an 800-mile, high-speed intercity passenger rail corridor stretching from Sacramento to San Diego. In light of that project's estimated $42 billion price tag, we can only hope that Vision California is right – that the benefits of Smart Growth and transit-oriented development are rich enough to justify the enormous costs of building the infrastructure required for a Green Future.

Adam Christian is an urban planner and is currently working on LA Metro's public-private partnership program.  He is the author of a 2009 Harvard Kennedy School case study on California High-Speed Rail.