While many urban planners laud compact urban design for its ability to restrict the use of cars for a more sustainable environment, one researcher finds that compact design does not necessarily correlate to decreasing car use.
An article titled “Does Compact Development Make People Drive Less?” by Mark Stevens, Associate Professor in the School of Community and Regional Planning at the University of British Columbia in Canada, finds that compact urban design planning reduces the use of cars just a bit. “I find that compact development does make people drive less, because most of the compact development features I study have a statistically significant negative influence on driving. The impact, however, is fairly small: Compact development features do not appear to have much influence on driving. My findings are limited to some extent because they are derived from small sample sizes,” he states in his abstract.
Instead, Stevens suggests introducing new options on the transit side, such as adding and expanding bus-rapid transit, trams, and rail or metro lines. He also finds other techniques more effective; such as eliminating parking spaces, providing more bike lanes, lowering speed limits, levying congestion charges on cars as they enter urban cores and banning vehicles from some streets.
However, other fellow urban planning professors described Stevens’s findings as exaggerated. “By far our greatest concern is that Stevens has overreached in his conclusions; which are not consistent with his results, or our earlier results,” Reid Ewing of University of Utah, and Roberto Cervero of University of California wrote together in response to Stevens’s report.
Stevens’s conclusions were that “compact development features do not appear to have much influence on driving” and that “planners should not rely on compact development as their only strategy for reducing driving unless their goals for reduced driving are very modest and can be achieved at a low cost.”
“We would never equate Stevens’s well-documented, well-reasoned, empirical study to Echenique’s poorly documented simulation study, but it may have the potential to do more harm simply because of its relative rigor combined with its overreaching on conclusions,” both urban professors argued.
In 2010, Ewing and Cervero’s conducted research on the relationship between urban density and car usage, concluding that: “The relationships between travel variables and built environmental variables are inelastic. The weighted average elasticity with the greatest absolute magnitude is 0.39 [for VMT is −0.22], and most elasticities are much smaller. Still, the combined effect of several built environmental variables on travel could be quite large.”