New study: Smart Growth works

Reduces CO2, VMT

Steve Hawley, Sep 01, 09.

A high-profile report requested by Congress was released Tuesday, indicating that compact urban development produces a number of benefits, including reduced vehicle miles traveled, lower greenhouse gas emissions, and reduced infrastructure costs.

The study, called “Driving and the Built Environment,” was completed by the Transportation Research Board and Board on Energy and Environmental Systems at the National Academies, and it was funded by the US Department of Energy.

The report says “dispersed, automobile-dependent development patterns have come at a cost, consuming vast quantities of undeveloped land, increasing the nation’s dependence on imported petroleum, and increasing greenhouse gas emissions that contribute to global warming.”

In quantifying development strategies, one finding says “Illustrative scenarios developed by the committee suggest that significant increases in more compact, mixed-use development will result in modest short-term reductions in energy consumption and CO2 emissions, but these reductions will grow over time.

The study concludes that more compact development could reduce greenhouse gas emissions by “less than 1 percent to 11 percent by 2050, although committee members disagreed about whether the changes in development patterns and public policies necessary to achieve the high end of these estimates are plausible.”

Other key findings:

Doubling residential density across a metropolitan area might lower household VMT by 5 to 12 percent, and perhaps by as much as 25 percent, if coupled with higher employment concentrations, significant public transit improvements, mixed uses, and other supportive demand management measures.
Significant increases in more compact, mixed-use development result in only modest short-term reductions in energy consumption and CO2 emissions, but these reductions will grow over time.
Changes in development patterns entail other benefits and costs that have not been quantified in this study.
Promoting more compact, mixed-use development on a large scale will require overcoming numerous obstacles.

Among the “other benefits and costs,” the authors conclude that compact development will reduce some infrastructure costs, increase public transit costs, preserve more agricultural and environmentally sensitive land, and provide greater opportunities for physical activity such as walking and biking.

The authors encourage policies that support compact, mixed-use developments, as well as continuing studies on the subject. Houston recently passed a transit corridors ordinance designed to encourage transit-oriented development along the city’s light rail lines.

Ryan Avent has commented on the report at Streetsblog.

Another recent report, “Growing Cooler,” came to similar conclusions, although it estimated the benefits of compact development to be slightly higher in some cases.

Separately, the Center for Neighborhood Technology has created a tool to calculate how urban density affects carbon emissions. The tool includes a graphic of the Houston-Galveston-Brazoria region.

Full study: Driving and the Built Environment
Executive summary: Driving and the Built Environment

Full book: Growing Cooler