Autonomous Chevy Bolts Are Already Becoming Left-lane Hogs


Check out this video from The Wheel Network, where one of GM’s autonomous Bolt EVs navigates San Francisco at night “without a single intervention from the technician in the driver seat.”


That’s what the YouTube description says, anyway. I’ve been sitting on this post for a while, but Justin’s recent post on Jalopnik reminded me of the autonomous prototype’s odd lane choices, and I figured it was time to polish this post up a little and publish it.

We don’t have footage of the recent incident with the motorcyclist, but watch the Bolt’s behavior in this 9-month old video. At 1:13, the Bolt makes a left turn onto San Francisco’s Cesar Chavez St, where it immediately selects the left of two available forward lanes. This is in line with the “F.A.L.L. into the First Available Legal Lane” practice. And the right lane soon becomes a right-turn-only lane, so one could hardly fault the car for staying left a little longer.

But soon afterward, an extra forward lane opens up again on the right, yet the Bolt continues to ride the left one for several blocks. Is it really selecting the left lane by default? Or could it be setting up for its impending left turn onto Indiana St (approximately 0.8 mile later)?


Is 0.8 mile close enough to just go ahead and take the left lane? I mean let’s be fair, it IS less than a mile away... And frankly, last-second lane changes aren’t much better than left-lane hogging. But traffic doesn’t seem heavy enough to justify claiming the left lane so early. In fact, it’s four whole minutes before the Bolt actually makes that turn.

Before it even gets to Indiana St, it gets “stuck” behind a left-turning Beetle, at an intersection without a dedicated left-turn lane. The Bolt waits approximately forty seconds for the Beetle to move, instead of, y’know, simply using the right lane to just go around. There is some traffic that does pass by in the right lane, but that traffic clears well before the Beetle moves. Who knows how much longer the Bolt would have waited?


Why do we even care about this? Well, because we’re talking about an automated system here. Once the developers make a decision about how early the car needs to leave the right lane to set up an upcoming left turn, the system is going to continue to aim for that target every time. Might as well decide on an optimal time (or distance) for this that helps keep traffic moving smoothly and predictably.

Where would you draw the line? How much time should a HAV spend in the left lane, especially around human drivers?

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