On September 1, the National Academy of Sciences released a congressionally-mandated report: Driving & the Built Environment: The Effects of Compact Development on Motorized Travel, Energy Use, & CO2 Emissions. The press release summarizes the findings:
. . . According to the committee that wrote the report, the most reliable research studies estimate that doubling residential density in a metropolitan area might lower household driving between 5 percent and 12 percent. If higher density were paired with more concentrated employment and commercial locations, and combined with improvements to public transit and other strategies to reduce automobile travel, household driving could be lowered by as much as 25 percent. By reducing vehicle use, petroleum use and CO2 emissions would also be lessened. . .
Government policies to support more compact, mixed-use development should be encouraged, the report says. The nation is likely to set ambitious goals to address climate change and, given the large contribution of the transportation sector to greenhouse gas emissions, changes in land use may have to be part of the effort. If so, land use changes should be implemented soon, because current development patterns will take decades to reverse. . .
(As a personal side note, the National Research Council's committee for this study included my former planning professor, one of my very special mentors, Rolf Pendall (now at Cornell University).)