In my ongoing thinking about the city as an interface – as an operating system, if you will, of this thing we call Earth – I picked up a book I bought while in grad school: Universal Principles of Design. It lists a multitude of various design elements and principles to consider when designing. I'm mentally listing which ones are relevant to analyze when thinking of urban interfaces.
I also think about new nomenclature to describe this design perspective, this intersection of interaction and urban design. For example, what would the equivalent of the term GUI (Graphical User Interface) be? How about UUI™? Urban User Interface™.
The two principles that first inspired me to think about the city as an interface (i.e., UUI™) were mental models and affordances. Mental models because of my frustration with learning a new urban plan when I moved from Seattle to DC. I couldn't find anything! Just finding a Target when I first got here proved to be maddeningly frustrating. The system provided no user feedback when I made a wrong turn or took the wrong exit. This was before my iPhone, so my metadata of the UUI™ was limited to one of those folded, laminated maps.
Mental Model – People understand and interact with systems and environments based on mental representations developed from experience. Lidwell, 130
As Seattle was the first major metropolitan area I have ever lived in, it serves as my base mental model of how the city as a product should work. Hence, my mental model for how the city was laid out upon moving to the DC was completely up-ended. Interestingly, learning Baltimore hasn't been as frustrating for me; my guess is that if you compared maps of the three cities, DC would be the outlier. Baltimore's urban layout is probably more similar to Seattle's than DC's.
Affordance – A property in which the physical characteristics of an object or environment influence its function. Lidwell, 20
Affordances in the context of the UUI™ are very interesting, I think. There are physical affordances, such as sidewalks, freeway exits, alleys, streets, parks and buildings. But there are also perceived affordances, those imposed by social implications and realities. These are the affordances that might prevent or discourage you from going into high-crime neighborhoods. For example, blue security cameras abound throughout many Baltimore neighborhoods, indicating that crime is such a problem there that 24-hour video surveillance is necessary.
There are many more, for sure, but this is the beginning of my categorical thinking. I'm also developing an NPR patterns library at work, which will further fuel my thoughts on this topic; what is the pattern language of urban design?
Lidwell, William, Kritina Holden and Jill Butler. Universal Principles of Design. Gloucester, MA:Rockport 2003.