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New Study Finds Roads Just Redistribute Growth-Changes in Transit-Oriented Development Could Balance Disparities

Highway critics have focused on the way new roads increase congestion when they should be looking at how road improvements redistribute regional growth, contends Robert Cervero, a University of California at Berkeley planning professor and author of a groundbreaking study published in the Spring 2003 issue of the Journal of the American Planning Association (JAPA).

Click here to read the complete article: http://www.planning.org/newsreleases/pdf/Cervero.pdf

"Roads induce growth at a corridor scale; however they don’t do so at a regional scale," Cervero found. "Induced growth along [highway] corridors is really redistributed regional growth."

The article is titled "Road Expansion, Urban Growth, and Induced Travel: A Path Analysis," and was supported by a grant from the University of California Transportation Center.

Cervero’s findings could have significant impact on billions of dollars of road projects as traffic forecasters try to unscramble the tangled interaction between congestion and new development. Many regional transportation plans have been mired in political squabbles over whether new roads increase sprawl and the extra vehicle trips associated with it. Highway critics have long claimed that improved roads fuel "induced demand" — additional travel or diverted trips from parallel routes. Cervero’s new research indicates that the claim might be exaggerated.

"The contention that capacity additions are quickly absorbed by increases in traffic and that "you can’t build yourself out of traffic congestion" might not hold in all settings," he found.

How road expansions induce development along highways — a phenomenon Cervero calls "induced growth" — may be more important than whether highway expansions decrease congestion.

"Congestion relief … does not necessarily make for a sustainable and livable metropolis," Cervero observed. "Thus residents of places that are able to build themselves out of traffic congestion might not necessarily like what they get."

"This is an important article on a very complex topic," said Stuart Meck, FAICP, a senior research fellow with the American Planning Association (APA). "State transportation departments often claim that they are only serving existing development, but this study shows that capacity improvements actually make matters worse in some cases, although the time frame is longer than many believe — as long as five to six years."

Cervero found that, over time, road improvements and the resulting swifter travel speeds spur building activities along highway corridors. That growth fuels more traffic which then erodes most of the speed benefits of added capacity.

"The dominant effect of building roads is likely to reshuffle growth within a region, not to add jobs and households," he concluded.

Cervero’s findings point up the need to do a much better job in managing regional development to balance the growth induced through highway expansions, Meck said.

One solution may be better planning of transit-oriented development (TOD). In an article in the May issue of Planning magazine, Cervero suggests that TOD in the United States is deterred by the huge parking lots surrounding metropolitan transit hubs.

"Not only do the big lots consume real estate near stations, but they also create unpleasant and sometimes unsafe walking environments," he notes.

Cervero touts "Green Connectors" — networks of pedestrian and bicycle friendly avenues that feed into major transit routes — as replacements for the asphalt jungles that take up valuable space that could be used for TOD. Green connectors have had enormous success in Europe and parts of Latin America. Cervero believes that carefully crafted public policies and planning visions can make them work here.

"If cities as varied as Stockholm and Bogota can successfully implement green connectors to trunk-line transit, so can American cities and suburbs," he claims.

Skeptics contend that experiences from Europe and Latin America cannot be imported successfully to the U.S. with its culture of independence and long love affair with the automobile.

That’s hogwash, responds Cervero.

"Americans reveal their distaste for walking in unappealing environs by going great lengths to find a parking spot close to a shopping mall entrance. Yet they think nothing of walking one or two miles once inside," he notes.

"The difference is that malls are generally dreary on the outside but engaging on the inside — a useful lesson for other places."

Whether highway expansions will redistribute regional growth and whether green corridors can jump start the kinds of TOD that can offset those effects will all depend on strategic transportation planning based on sound econometric modeling. Cervero’s studies and creative ideas provide a starting point in developing robust models for creating more livable communities.

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Contacts
Chris Cooper, APA Public Affairs, 202-872-0611 x1007

http://www.planning.org/newsreleases/2003/ftp050803.htm

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