…or maybe some oddballs walked

In our tribute to Jane Jacobs this week, the following is classic Jane. Here’s a favorite study conclusion she included in her last book, (pg. 75.) The question is what happens when you close roads? The study findings from over sixty cases worldwide:

“Planner’s models assume that closing a road causes the traffic using it to move elsewhere… The study team… found that computer models used by urban transportation planners yield incorrect answers… When a road is closed, an average of 20% of the traffic it carried seems to vanish. In some cases they studied, as much as 60% of the traffic vanished. Most of the cases studied involved urban areas, but the same arguments may apply away from urban areas, New Scientist reports. The report at hand is a logical extension to a 1994 finding that building new roads generates traffic. If that’s the case, “then the closure or roads is bound to cause less traffic,” according to London-based transport consultant Keith Buchanan.”

Jane’s reasoning why cities rarely ever considered closing roads in spite of the aforementioned evidence, “Where did the vanished traffic go? This was a new question that emerged unexpectedly. But it was not pursued. It was ignored in favor of a vague notion that some drivers must have chosen less frustrating routes, or else switched to public transit; or maybe some oddballs walked.

*Research conducted by a team at University College, London, for London Transport and Britain’s Department of the Environment, Transport, and the Regions