A template for an urban street in "Designing Walkable Urban Thoroughfares." Source: Claire Vlach, Bottomley Design & Planning.
One of the foundational documents in our country's history of car-centric street design is what's known as the Green Book. These engineering guidelines, which have been published in various editions by the American Association
of State Highway and Transportation Officials (AASHTO) since the 1930s, are only "green" if you're looking at the cover.
"We should take control of our streets. If 85 percent of our motorists are driving faster than we want them to, then we need to redesign the street."
Inside, the Green Book codifies an anti-urban design approach that transportation engineers have followed to disastrous effect in American cities and towns, creating wide streets where cars rule, speeding is the norm, and the greenest modes of travel have no place. While its recommendations are only advisory, the Green Book is often treated as gospel, implanting ideas like the "85th percentile" standard, which dictates that streets should be designed to "forgive" the 15th-fastest driver out of every hundred on the road. In the words of former Maryland transportation chief James Lighthizer, this is like building streets as though "everyone on the road is a drunk speeding along without a
Fortunately, these engineering standards are shifting. One important step is a new report co-authored by the Institute of Transportation Engineers (ITE) and the Congress for the New Urbanism (CNU). "Designing Walkable Urban Thoroughfares: A Context Sensitive Approach" aims to define a more humane engineering language for streets. The report is intended to supplement the Green Book by laying out a set of design standards that make sense in places where people can get around by foot or on a bicycle.
If, as U.S. DOT Secretary Ray LaHood recently pledged, walking and biking are going to have equal standing with motorized transport, more enlightened engineering guidelines will have to play a significant role. To better understand how the CNU/ITE report can influence state DOTs and the way they shape streets, we spoke to one of the experts who helped develop it, Dan Burden.
As the founder and executive director of Walkable Communities, Inc., Burden travels the country helping people plan and develop more sustainable neighborhoods. In 2001, Time Magazine named him one of the six most influential civic leaders of tomorrow. Burden spent 16 years as bicycle and pedestrian coordinator for the Florida Department of Transportation, so he was able to share with us his experience as both an advocate and an administrator.
Here's the first part of our interview:
Noah Kazis: Let's start with that new ITE and CNU report that you participated in. What's its significance?
Dan Burden: A couple of big breakthroughs occurred with that publication. One where we struggled hard, but finally broke free, is setting a target speed for roads. Before, there was always the driving speed, which had to be higher than the posted speed to provide "forgiveness" to drivers. Of course, drivers totally figured that one out, and they'd drive faster than the posted speed. In these guidelines, they're supposed to design the road for the speed that we want to elicit from the driver.