Increasing density could mean reductions in vehicle travel, fuel use and CO2

WASHINGTON — Increasing population and employment density in metropolitan areas could reduce vehicle travel, energy use, and CO2 emissions from less than 1 percent up to 11 percent by 2050 compared to a base case for household vehicle usage, says a new congressionally mandated report from the National Research Council, although committee members disagreed about the plausibility of achieving the higher estimate. Assuming compact development is focused on new and replacement housing — as converting existing housing to higher densities could be prohibitively difficult — significant increases in density would result in modest short-term reductions in personal travel, energy use, and CO2 emissions. However, these reductions will grow over time.

Currently, 80 percent of Americans live in metropolitan areas, but population and employment are increasingly decentralized. This trend of suburbanization, made possible largely due to automobiles and extensive highway systems, reflects the preferences of many Americans for living in detached, single-family homes. Dispersed, automobile-dependent development patterns, however, involve numerous costs: the use of vast quantities of land, increased reliance on petroleum, and increased greenhouse gas emissions. Compact, mixed-use development — individuals living in denser environments with jobs and shopping close by — could reduce the number of vehicle miles traveled by shortening trip lengths, the report says, and by making walking, biking, and public transit more viable alternatives to driving.

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.

EurekAlert