Study Shows "Sprawl" Reduces Commuting Time
Common sense suggests that as communities spread outward, residents should expect longer commutes. As Melody Flowers of the Sierra Club states, "What's troubling about this increase in commute time is that it's largely due to poor planning that takes choices away from people. Scattered development and haphazard road-building are leaving commuters stuck in their cars, instead of spending time with their families or at work." [1] This, fortunately, is not proving to be true. Empirical evidence now shows that as development spreads, commutes shrink.In, “Traffic and Sprawl: Evidence from U.S. Commuting, 1985 To 1997,” a new study published in the September issue of the journal Planning and Markets, UCLA professor Randall Crane and Ph.D. candidate Daniel G. Chatman examine the relationship between how communities grow and how work trips respond. [2] Their results may overturn conventional wisdom about growth and travel patterns.
In the study, Crane and Chatman analyze data from The Census Bureau, The Bureau of Economic Analysis and The Bureau of Labor Statistics. They first find that population and employment in outlying counties of metropolitan areas has risen significantly. They also find that the average commuting distance is on the rise, as well. If they had stopped here, their research would have done little more than confirm established ideas.
When the two began to investigate further, though, they found that sprawl actually tends to reduce commute distance. How can this be? “[T]he marginal effect of job suburbanization appears to be to bring jobs and workers closer,” explain Crane and Chatman. In other words, while commute distance may on average be increasing, the increase is not necessarily a by-product of growth patterns. “[T]he average commute would be longer still,” say the authors, “if jobs were not suburbanizing.” [3]
In fact, entirely separate factors appear to be influencing rising commute times. As incomes rise, for instance, commutes tend to increase in both number and length. In addition, certain types of work such as manufacturing and government employment are associated with longer commutes where others such as construction and retail sales are not. [4]
Based on these results, policymakers would do well to avoid placing restrictions on growth as a method of combating rising commuting times. Indeed, the decentralization of employment and population may be one of the few things effectively alleviating this concern.
Notes
[1] David Willett, “New Census Findings on Increased Commute Time Reflect Impacts of Sprawl,” The Loma Prietan (Palo Alto, CA: The Loma Prieta Chapter of the Sierra Club, July/August 2002). Available at: http://lomaprieta.sierraclub.org/.
[2] Randall Crane and Daniel G. Chatman, “Traffic and Sprawl: Evidence from U.S. Commuting, 1985 To 1997,” Planning and Markets (Los Angeles, CA: University of Southern California, September 2003.) Available at: http://www-pam.usc.edu/.
[3] Ibid.
[4] Ibid.
