Making Streets for Walking: Dan Burden on Reforming Design Standards
9:03 AM PDT on April 8, 2010
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 ourmotorists are driving faster than we want them to, then we need toredesign 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.
workshop in Lepeer, Michigan this February. Image: Michigan
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.
NK: Who is the target of this report? Who's going to be
implementing its recommendations?
DB: Any city or county engineer -- anyone who is going to
be professionally responsible for setting street standards for their own
community -- will be able to find that now there's an official resource
provided by the Federal Highway Administration that they can pull
language from. It is truly an authoritative source. This collective body
of professionals got together and agreed upon these new criteria.
NK: Is this a shift for ITE? Many of us think of
transportation engineers as very conservative, very car-centric.
"The AASHTO GreenBook is built for rural America and for suburban America. It was neverdesigned for downtowns. It was never designed for the averageneighborhood street."
DB: It is a
shift for ITE. ITE, fortunately, is a little more progressive than the
AASHTO, the American Association of State of Highway Transportation
Officials, but this is a significant advance. It represents a blending
of the transportation industry with the Congress for the New Urbanism. I
don't think ITE on their own would have been quite as bold. But with
the leadership of the CNU, they really were able to bring in the best of
NK: Besides bringing the posted speed and the design speed
into alignment, what are the other innovations in this report?
DB: A lot of language was created to allow a more liberal
interpretation of flexibility. We shouldn't force any given category of
street to fall under very tight constraints. We really need permission
to build narrower roads, to use less asphalt, to green up the streets,
to emphasize the need for walkability and bicycling, to bring down
speeds on roads.
bike lanes requires changing details like the turning radius of an
We shouldn't just use some antiquated
language that says we have to post the speeds according to what 85
percent of motorists are doing. Instead 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, rather than letting the
tail wag the dog. There's something wrong with our street design if
you're getting 85 percent of our motorists to drive 10 miles an hour
faster than is safe for the conditions.
The report sets the platform for creating that livability. It covers
the planning aspects, it gets into the broad-based principles and then
it gets down to the exacting details and explains why 10-foot and
11-foot lanes are superior to wider lanes. It gives more flexibility
while providing specific language that an engineer and a planner could
pull for their own street standards.
NK: How do these guidelines and recommendations get turned
into change on the street? Where does the federal government come in?
The state and local governments?
DB: First of all, there's always been a misunderstanding
about federal standards. It doesn't matter what state I go to; I can
hear some folks in the state agency say, "Well we have to do this,
because the federal government says that these are the standards." The
federal government does not set standards. They help create
publications, they provide a lot of guidance, but they truly have no
desire or ability to set the standards that a local government would
The key is influencing those in state government to realize that
they're in charge, that whatever language they create can then be
inserted in a local street system that happens to involve state funding.
In some states, the total street system, from an alley to a lane to an
arterial, is set by state guidelines. In Florida, we have what's called
the Green Book committee; I used to sit on it for about 15 years. We
came up with guidance for what every category of road would be and then
whoever built the road -- certainly any private developer -- had to
follow those standards if they wanted to turn the road over to the
community. They gave a baseline for certain margins of safety and
"The clear zonethat's required -- how far you have to set back trees or other fixedobjects from the roadways -- was determined years ago by one phone callfrom a committee of AASHTO to the General Motors test track."
problem of having standards that every community in the state must
follow is that it doesn't necessarily give the best level of
flexibility. If a community writes their own street design guide, then
they can totally revamp: They can come up with flexible streets, curving
streets, living streets, all the terms we're now using. So it becomes
imperative to get street making down to a local level. You still need to
be predictable at a state level, though. This guide helps give the
language that a local community might need to narrow streets or provide a
different level of street connectivity. That's something that needs
NK: So are you arguing that states should take a step back
from transportation planning and let local governments move in?
DB: Yes I am. I feel that the people who end up populating
the committees that set these standards are not keeping their ears close
enough to what's going on in a given neighborhood. By the time you're
high enough up in the chain of your state agency, you no longer go to
public meetings, you no longer read every document that comes out. So
you're trying to make decisions that are good for everybody, even though
you've reached a point in your career when you're no longer grassroots.
NK: What does that detachment lead to?
DB: You feel like you have a responsibility to keep raising
the bar but in many cases the bars gets raised with absolutely no
scientific evidence. For example, the clear zone that's required -- how
far you have to set back trees or other fixed objects from the roadways
-- was determined years ago by one phone call from a committee of AASHTO
to the General Motors test track. So they're talking to one person at
the test track -- for cars -- and the guy said 100 feet and [AASHTO]
said, "No, that can't work, we can't buy 200 feet of right of way
everywhere." So they negotiated and said 60 feet would eliminate a lot
of the crashes. That's how they determined it. If you went back and
studied how a particular measure came to be, it's, "OK, if I agree with
you it should be 15 feet rather than five, then will you agree with me
on my point about this topic?"
the street should influence the design of the street itself.
NK: In terms of the internal politics of state departments
of transportation, is there some sort of bias in how the roads are
DB: Historically the AASHTO Green Book, which is still what
most people will quote and many state design guidelines are built
around, is built for rural America and for suburban America. It was
never designed for downtowns. It was never designed for the average
neighborhood street. It was designed for this new America we were
building, where we wanted to keep the greatest flow of vehicle movement.
So we come up with things like turning radii on the corner of an
intersection, driveway flows, everything based on a suburban and a rural
NK: Do you think that momentum toward livable streets --
among both engineers and the state departments of transportation -- is
going to continue?
DB: I know it's going to continue. For example, take
complete streets. Every state that adopts a complete street philosophy
now comes together to try to figure out, well, What does this really
mean? So it builds on itself. I was in Columbus, Ohio, where the state
has adopted a complete streets package and now everybody is quickly
trying to figure out, Do we always have bike lanes or do always have
this or that? So, yes, I think that, along with Secretary LaHood's
recent comment that pedestrians and bicycles will have equal
considerations in designing and building and funding our streets, that
this is shaking up the industry.
Obviously we're crafting new buzzwords and we've got more
enlightened secretaries of transportation, but we're also going to
realize we cannot continue to build roads that are not sustainable. They
create more drainage impacts, more heat gain, more use of oil for
asphalt or processing concrete. These resources are going to put us in a
non-compete situation with the rest of the world where we're just
trying to keep our system working. In many cities now the individual is
spending 20 percent, even 25 percent, on their transportation out of
their take-home pay. That's not sustainable at a personal level.
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