A Happy Thought

There may actually be some positives to the impending arrival of self-driving cars.

Yeah, I know, that sounds odd coming from me, doesn’t it? But it’s true.

Consider the case for predictability. Many of the concerns I see about self-driving cars boil down to “How do I know what it’s going to do in Situation X?”

How do you know what any driver is going to do in Situation X? In truth, you mostly don’t. You guess, based on your experience, your familiarity with the law, and what you’ve seen of the driver’s behavior. Usually you haven’t seen much of the last. If they’re doing something blatant–speeding, weaving back and forth across the lanes, going the wrong way on a one-way street–you pay special attention to them. But for the majority of drivers, you’re guessing.

How many times have you seen someone sit at a green light because traffic is backed up from the next light, so there’s no place to go? Not very often, at least around here. The default assumption is that two or three cars will move into the intersection and still be sitting there when the light changes. Now the cars on the cross street are blocked. Presto! Instant traffic jam.

And yet, this morning I saw three different cars waiting at green lights for the traffic ahead of them to move. It was startling enough that I took special note.

My point is that over time, we’ll build up a category of experience specific to self-driving cars. We’ll assume they’ll wait at green lights instead of blocking intersections*. And we’ll make that assumption because we’ll see them do it every time. Not just on days when they’re not late for work, didn’t have a fight with a loved one, or feel like being passive-aggressive.

* Assuming they weren’t programmed by Bay Area drivers.

We’ll be able to make better predictions about what they’re going to do than we will about all those human drivers on the road.

That’s a good thing, but here’s an even better one.

Even a tiny number of self-driving cars on the road have the potential to break up traffic jams before they start.

Seriously.

Okay, I’ll admit I’m extrapolating wildly from a study I saw back in the days before journal papers went online. But I’m a science fiction writer; wild extrapolation is part of my job description.

The gist of the study was that one of the common reasons traffic jams develop is that a few drivers slow down. The drivers behind them overreact and slow further, then speed up to close the gap. Errors accumulate, and again, Presto! stop-and-go traffic.

I see this every day. There’s a curve on the freeway where most drivers slow down from 65 (or whatever faster-than-the-limit speed they were going) to 60. Outside of commute hours, it doesn’t matter. Everyone slows a bit, then resumes speed on the next straight patch. But at rush hour, that curve always turns into a parking lot.

But the study went further. The investigators found that if a small percentage* of the drivers maintain a constant speed–even if that speed is well below the limit–instead of braking and accelerating, the jam never develops.

* I want to say five percent, but I’m working with twenty-year-old memories, so that may be incorrect. I am sure it was a single digit number.

Self-driving cars, if properly programmed, aren’t going to slow down for a curve they can safely negotiate at the speed limit. More to the point, if they get proper information about traffic conditions ahead of them, they won’t get into the slower/faster/slower/faster cycle that causes jams. They’ll just slow to the maximum speed that won’t result in a collision.

Maybe that doesn’t sound like such a big deal to those of you outside the Bay Area and other commute-infested regions. But not sitting in stationary traffic on that one single stretch of freeway would trim my morning commute by ten minutes. And there are two other spots on my normal route where traffic behaves the same way.

Saving half an hour a day and however much gas the car burns idling in traffic sounds like a very good deal to me.

 

4 thoughts on “A Happy Thought

  1. I often base expectations of driver behavior on what sort of car they’re driving. Not always reliable, but often helps. I’m sure I’m one of those people who overreacts to people slowing down ahead of me, because I’ve spent so much time on I-5 going from 70 to 0 in a couple of hundred feet.

    Like

    • I’ve always been wary of a red or black car with a temporary plate. Red, especially, and the sportier the more dangerous.

      Beige cars will probably drive slowly in the left lane.

      Like

      • Where permissible, insurance companies charge higher rates for red cars, or so I’m told. Not sure about black, but wouldn’t surprise me.

        And beige cars will drive slowly in all lanes, not just the left.

        Am I stereotyping? Guilty.

        Liked by 1 person

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