A new studyon how design and planning can keep these numbers down. (Photo: Amy the
Nurse via Flickr)
How the heck can we get people to drive less?
That’s one of the most vexing questions facing sustainable
transportation advocates. Higher gas prices seem to do the trick,
although anecdotal evidence suggests that watching an entire ecosystem
being destroyed by a busted oil well doesn’t
have much effect.
The fact is, too often we are engaging in guesswork and speculation
when we talk about strategies to reduce vehicle miles traveled (VMT).
But thanks to a new study of how land use affects transportation
choices, we now have a great new source of actual data. The study, a
meta-analysis of 50 previous studies, is called "Travel
and the Built Environment," and it’s published in the Summer 2010
issue of the Journal of the
American Planning Association. It’s the result of several years’
work by Reid Ewing of the University of Utah and Robert Cervero of the
University of California, Berkeley.
Kaid
Benfield at NRDC Switchboard did a great job of summing up their
conclusions:
What they found: location matters most when it comes to land use,
driving and the environment.The study’s key conclusion is that destination accessibility is
by far the most important land use factor in determining a household or
person’s amount of driving. To explain, ‘destination accessibility’ is a
technical term that describes a given location’s distance from common
trip destinations (and origins). It almost always favors central
locations within a region; the closer a house, neighborhood or office is
to downtown, the better its accessibility and the lower its rate of
driving. The authors found that such locations can be almost as
significant in reducing driving rates as other significant factors (e.g.,
neighborhood density, mixed land use, street design) combined.
Daniel Nairn at Discovering
Urbanism also wrote about the study, pulling out a thread about
connectivity on the street-grid level:
[The study is a] big win for connectivity, which is greatbecause this is something that can actually be done. Some cities and states are starting to write codes to ensure a robust street network in newdevelopments. Even more important is retrofitting connections into existing networks. Hopefully these results willspur localities to look for those odd scraps of land and considerpunching a street or multi-use trail through them. Although cycling wasnot considered in this analysis, I can attest from personal experiencethat street connectivity is the single most important factor forenhancing safety and convenience.
More excellent analysis, focusing on the importance of intersection
density, can be found at Lawrence Aurbach’s Ped Shed.
More from around the network: Livin
in the Bike Lane on the effect of air pollution on bicyclists (this
is not good news, folks). On
Two Wheels wonders if Montréal could benefit from fewer traffic
signs. And The Bellows
considers the benefits of congestion.
