Jeff Speck has a great method of framing the way we think about automobiles: he calls the car a 'prosthetic device.' Speck gave great talk outlining the problem statements regarding population growth, global warming, energy insecurity and suburban sprawl. His solution is the Walkable City, a place where it makes more sense to walk from place to place instead of taking public transportation or our own vehicles.
In the newer talk 4 ways to make a city more walkable Speck gives a plan for implementing the ideas and making a large space more friendly to walking and biking. Jeff defines the typical American city as Grand Rapids, Cedar Rapids or Memphis - an environment where most people use cars as their sole means of transportation. To get these people to walk they will need a value proposition that's at driving level quality, or better. He calls this his General Theory of Walkability.
His four needs for a walking city are: There needs to be a proper reason to walk, the walk has to be safe and feel safe, the walk has to be comfortable, and the walk has to be interesting.
What Speck calls Euclidean zoning worked during the industrial revolution because the poisonous factory smoke was moved away from the living areas. But today having a zone where you work, a zone where you live, and a zone where you shop takes away the possibility of walking from one zone to another.
After Oklahoma City was called 'the worst city for pedestrians' the mayor came to Jeff and asked for help. A walkability study showed that most streets had less than 10,000 vehicles traveling them per day, the threshold for needing more than two lanes to meet demand. But many of the streets were tagged to be expanded to four or six lanes wide and that causes more traffic to use the streets, making the streets less appealing to pedestrians.
Jeff Speck is a great speaker with a dry sense of humor and wry delivery. He clearly explains the complex issues facing a modern city and his methods of studying those systems before presenting possible solutions. This talk is a few years old but a solid examination of the ways that civil engineering and urban planning can shape the future of how we live.