So I keep telling people, "I'm reading this fascinating book about traffic,' and they're like, 'that doesn't sound that fascinating...' But actually, anyone who drives tends to have strongly held pet theories and peeves (and those who don't will generally have their own, from the vantage point of a non-driver), and this book explores them all.
It's essentially a work about systems and human input into them; so we move from 'traffic' as a phenomenon to efforts to influence it (whether in terms of safety or flow) which inevitably bring us to the question of human psychology. A lot of common assumptions are squashed here: for example, 'safer' roads, and safer cars, aren't actually safer because they lull us into a false sense of security and encourage us to ramp up the risk level of our own driving. As Vanderbilt points out, if an engineer built a dam to hold a certain water pressure, they wouldn't have to factor in how the water would respond to its knowledge of the dam being built to those standards...
It's the psychology that's the most interesting issue here. Although I'm not generally a fan of evolutionary psychology, Vanderbilt suggests convincingly that humans are not 'designed' to deal with moving at any more than 20 miles an hour, nor with interactions in which the other parties are 'faceless' and we have no investment in the local community. In such a situation, all of our methods of assessing risk, coping with crisis, and so forth, can be highly maladaptive. He also explains a lot of misperceptions: why, for example, does it always seem like we're being passed more often than we overtake? (because cars we pass immediately disappear from our field of vision, whereas those which pass us stay there for much longer).
You'll also find a lot of your ideas about the 'morals' of driving challenged. For example, I tend to be a driver who thinks that going up the empty outside lane then merging at the last moment is queue-jumping, but Vanderbilt points out that everyone will get where they're going faster if two lanes are being used to their capacity.
Ultimately, this reader came away thinking that we're never really going to be able to scientifically 'figure out' answers to any of the big questions in regard to any activity as complicated, and subject to human factors, as driving. That also goes for safety, which is a somewhat scary prospect... Nonetheless, for an activity which the majority of people spend a great deal of time doing, and doing in a mostly 'unconscious' fashion - as well as one for which we're prepared to accept tens of thousands of deaths annually - driving, and traffic, haven't been the subject of much writing outside the realm of the specialist, and this is an amusing and thought-provoking book, written in a light and humorous style, which goes some way to addressing the issue.