Most of us are bad drivers, but usually it doesn't matter

When I was learning to drive the ambulance, our director said, as part of our training, "remember: 90% of driving is routine. It's when the routine is broken that accidents happen." Her point was that an emergency vehicle, in proceeding through a red light, driving left of the double yellow line, proceeding the wrong way down a one way street, etc, was breaking the routine, so extra caution was necessary to do so.

I now think that she underestimated the amount of driving that qualifies as routine - I'd put the number closer to 95% or even 99%, but her basic point is correct. We know to stop at a stop sign, and we know, too, that it is the rare driver who actually stops - most of us slowly glide through if we can do so; the ride is much more comfortable. We know which side of the road to drive on - when faced with a double-yellow line we don't have to think about how to react to it. We know that the amber light on the traffic signal heralds the red, so we'd better mash the gas so we don't have to wait the 40 seconds for the green light to come back; most of us seem to have forgotten that the amber light actually means "stop if you can do so safely". We are familiar with the flow of traffic and our place in it, we call upon our experience, and most of the time, things go well.

Problems arise when things don't go as we expect. A tire blows and our control of our car is reduced. The road surface changes drastically, and again our control is reduced. We have a green light, but due to a streetlight malfunction, we also have a red light - as does everyone else: we all proceed into the intersection and collide. But unless this happens, we tend to arrive safely at our destination, in spite of our efforts to the contrary.

Because we do actively undermine our safety. We drive too fast, we follow too close, we distract ourselves with coffee, donuts, cellphones, and reading directions. We never check the pressure on our tires. We don't read the owner's manual to our vehicles. Many of us can't be bothered to wear a seatbelt. We drive when we're impaired by drugs (typically ethanol, though OTC and prescription drugs, and other drugs are also sometimes to blame) or a lack of sleep. Because driving is easy, right?

Well, no. Or maybe more accurately, driving is easy, but driving safely is not.

This isn't necessarily our fault. We're used to our own scale, and we're designed to react to our own scale. If I weigh 140 lbs, then I'm used to moving 140 lbs around; I have a sense of how fast I can accelerate, and how fast I can stop, how tightly I can turn. If I want to pick up a heavy box, I know that the effort require to do so will relate directly to the mass/weight of that box - there's an intimate feedback that lets me know how much weight I'm dealing with, and thus how careful I need to be as I move that weight.

A small car, though, weighs about one ton. Large SUVs exceed four tons, and large trucks can weigh much more than that, but I can get those tons of machinery to move with less effort than it takes to walk - I just press on the accelerator. if I want to change my direction, I move my arm and twist a wheel, and I've probably got power steering in case that's too difficult. Stopping takes the push of a different pedal; that probably has power assist, too. The feedback is lost. The ease with which I can get the car to move belies the potential difficulty I will have in bringing it to a stop. So without meaning to, I drive too fast, follow too close. My success as a pedestrian complicates my job as a driver.

There is also the theory of risk tolerance, or risk homeostasis. According to this theory, we each have a degree of risk with which we are comfortable, though this varies between individuals. If our risk is reduced, we are willing or driven to take steps to raise the level of risk to the our level of comfort. For instance, if my car has antilock brakes, I am willing to drive the car harder and demand more of the braking system, and my likelihood of crashing remains the same. As our roads get safer, we drive faster. Similarly, safer cars yield higher speeds. I think there is something to this - armed with air bags, some drivers refuse to wear seatbelts (which is one of the more idiotic examples, as the airbag requires the seatbelt if it is to be effective, say nothing of the possibility of being hit multiple times in the same incident).

It is thus not surprising that some emergency workers have started to use the term motor vehicle collision (MVC) instead of motor vehicle accident (MVA). with all that we do to undermine our safety, they argue, a collision is waiting to happen, and is no accident. (In a similar vein, some medical practicioners are abandoning the term cerebrovascular accident (a term that includes strokes and transient ischemic attacks).)

More on this later - this post is getting to be too long.