Streetfilms interviews Traffic author Tom Vanderbilt.
Mark: [3:41] Let me see if I can find this in your book. "Vehicles are moving at velocities for which we have no evolutionary training. For most of the life of the species, we did not try and make interpersonal decisions at speed." We live in a city where you have this interaction between people moving down the street at pretty fast speeds and the people who are on that street, and how they're almost in a completely different worlds.
Tom: [4:08] You probably begin to lose eye contact at around 20, 25 miles per hour. That's exactly when the level of potential pedestrian fatality really begins to soar. At up to 20 miles an hour a pedestrian still has a pretty good chance of surviving a crash with a car. But beyond that, it really begins to accelerate. So just at that moment when we cut ourselves off from the eye contact is really that moment at which we're not evolved to be able to survive an impact. So just an interesting sort of suggestion that's been put out there.