Sunday, October 07, 2007

Traffic Calming

We're discussing speeding in my neighborhood these days. Traffic calming is an important piece of the pedestrian-friendly puzzle. Fortunately, there's been a lot of energy in this area around the world recently. In many cases, conventional wisdom is being turned on its ear.

Some keys to effective traffic calming:
  • Perceived Danger. People have a safety threshold, and they drive right at the edge of it. Children and toys in the street, parked cars on the side of narrow roads, exuberant foliage that limits visibility, all serve to raise people's perceived danger and slow them down. Of course, this perceived danger can be accompanied by actual danger; we certainly don't want any of these kids to get hit. With this in mind, the question becomes how do we increase perceived danger while simultaneously decreasing actual danger. Fortunately, studies have shown that streets that look dangerous are often quite safe, due to the change in people's behavior. The key is to make the dangers and uncertainties as obvious as possible.
  • Antagonism vs Cooperation. The trouble with traditional traffic calming techniques such as speed bumps and stop signs is that they only serve to increase the antagonistic relationship between cars and pedestrians. Drivers are resentful of these periodic impositions and so they gun it between devices, wrapped up in their own inconvenience, paying even less attention to the pedestrians. Instead, you want to encourage brotherhood and cooperation between drivers and pedestrians. They need to relate to each other as people. In fact, just making eye contact and a friendly gesture is enough to slow a driver down.
  • "Going Somewhere" vs "Being Somewhere". We all have two modes, whether on foot or in a car: "going somewhere" on the highway or down a hallway, and "being somewhere" on a quiet residential street or a living room. In the former, our mind isn't really on where we're at; we're already thinking about where we're trying to get to. In the latter, we're present to the moment and responsive to the situation around us. In the case of streets, what mode you're in is greatly effected by the design of the street and the buildings that face it. Residential streets should feel like a living room, like a place you'd like to slow down and enjoy. Of course every city needs a mixture of of both modes; the trick is to make the distinction obvious.
With the above in mind, here are some suggestions for calming our streets:
  • Decorative "gateways" at the borders between the "going somewhere" streets and the "being somewhere" streets, so people feel like they're entering a special space, rather than just passing through.
  • Cobblestones at intersections or throughout the street.
  • City Repair-style murals on the surface of key intersections.
  • Benches on the side of the road, facing the street, to encourage the visible presence of people.
  • Paint the edges of the street to reduce perceived lane width.
  • Prominently displayed children's art, to show that children are present, in a more effective way than "Children At Play" signs.
  • Roundabouts, which tend to slow people down without the antagonistic effect of speed bumps and stop signs.
  • Block part of a lane off with planters.
For an interesting take on the subject, I recommend the book Mental Speed Bumps.


Thursday, December 29, 2005

Organic Design

So how does one create in a more organic way? Some patterns to consider:

Shorten Feedback Loops: The shorter the path from creation to use and back to creation, the more fluidly things can evolve. Examples abound: web vs. traditional publishing; wiki & blogs vs. traditional web; iterative software development vs. "waterfall"; smaller teams, focused projects (see Less as a Competitive Advantage); houses people can easily modify (see Stewart Brand's How Buildings Learn); small pieces, loosely coupled.

Embrace Fuzzy Principles: Not everything that counts can be counted, and not everything that can be counted counts. Even if you don't have metrics for something, perhaps especially so, if you think it's important, make it an explicit guiding principle. This is made easier with shorter feedback loops: after all, metrics are just a way for us to grasp that which is too big for us to get an intuitive sense of.

Trust Your Instincts: The human mind and spirit are amazingly rich breeding grounds for creativity. Don't let yourself get bogged down in justifications when you already know what's right. In fact, embracing fuzzy principles is possible only if you allow yourself to trust your instincts.

Patterns, Not Rules: As we go about our work, we often discover useful practices that help us work better. It's tempting to turn these into rules to lock in their innovation. The problem is that rules are rigid and circumstances change. Better to declare patterns: nuggets of wisdom packaged for easy use. Trust in the individual's instincts to select the right set of patterns for the situation, thus shortening the feedback loop between pattern selection and pattern use. (Are patterns just rules you don't take strictly? Sure, in the same sense that tags are just loose keywords. Terminology matters.)

Question Purity: Purity is very appealing, and it has an important place in the world, but probably not in your creation. Life is full of imperfection, constantly adapting. If you find yourself falling under the sway of a single design ideology or a pure mathematical formula, remember to leave a little room for funkiness.

Grow, Don't Build: Think in terms of creating a supportive space and providing the right resources to let your thing grow. See Kevin Kelly's Out of Control.

Observe Christopher Alexander's 15 Properties of Life: 1. Levels of Scale, 2. Strong Centers, 3. Boundaries, 4. Alternating Repetition, 5. Positive Space, 6. Good Shape, 7. Local Symmetries, 8. Deep Interlock And Ambiguity, 9. Contrast, 10. Gradients, 11. Roughness, 12. Echoes, 13. The Void, 14. Simplicity and Inner Calm, 15. Non-Separateness. For more detail, check out his The Phenomenon of Life, or this write-up (from a software perspective).

I'd love to hear your experiences using these and other related patterns.