My former co-blogger reads about Hans Monderman, the madman/genius who took out the street signs and traffic restrictions in a Holland town, with surprising results:
As I watched the intricate social ballet that occurred as cars and bikes slowed to enter the circle (pedestrians were meant to cross at crosswalks placed a bit before the intersection), Monderman performed a favorite trick. He walked, backward and with eyes closed, into the Laweiplein. The traffic made its way around him. No one honked, he wasn't struck. Instead of a binary, mechanistic process--stop, go--the movement of traffic and pedestrians in the circle felt human and organic.
A year after the change, the results of this "extreme makeover" were striking: Not only had congestion decreased in the intersection-- buses spent less time waiting to get through, for example-- but there were half as many accidents, even though total car traffic was up by a third. Students from a local engineering college who studied the intersection reported that both drivers and, unusually, cyclists were using signals-- of the electronic or hand variety-- more often. They also found, in surveys, that residents, despite the measurable increase in safety, perceived the place to be more dangerous. This was music to Monderman's ears. If they had not felt less secure, he said, he "would have changed it immediately." Emphasis mine.
When thinking about human behavior, it makes sense to understand what people perceive, which may be different from how things are, and will almost certainly be very different from how a removed third party thinks them to be. Traffic accidents are predominantly caused by people being inattentive. Increase the feeling of risk, and you increase the attention. I know when I am in traffic on my bike, I'm hyper-vigilant, and this has made me a better car driver.
This is an electoral problem. What are we trying to consume: actual safety, or the feeling of safety? This is a more important question than it looks like. Feeling safe is an actual good that improves people's lives; if you spend a lot of time worrying about terrorist attacks, your quality of life is lowered even if you're never actually killed by a terrorist.
The problem is that in this case, there's a direct tradeoff between actual safety and feeling safe. The safer people feel on the road, the more likely they are to get into accidents--which is why lots of innovations, like seatbelts, have underdelivered in mortality improvements. Load up someone's car with a seatbelt, anti-lock brakes, etc., and you get big gains in safety, which are then at least partially eroded because people who feel their cars are protecting them are more likely to drive like morons. Tragically, they are at least as likely to hurt someone else as they are to hurt themselves. There's nothing quite so infuriating as seeing some idiot with southern plates driving his jeep too fast in the snow because he doesn't realize that four wheel drive provides faster acceleration but does nothing for his stopping radius. Too often, he gets a rapid education in automotive physics when he skids into the back of a minivan being driven at sensible speed.
The other problem is that politicians do themselves no good by delivering actual safety if it is accompanied by a perceived increase in risk. So we get laws, from traffic stops to airport security, that enhance the perception of security while doing little-to-nothing to actually make us safer.