[bryanlarsen]

The answer to almost all of these hypothetical problems is "hit the brakes". Speed is the main killer in automobile accidents, it's a power law. Just a small reduction in velocity can have a dramatic impact on the survivability of an accident.

What about the question of whether to swerve into traffic to avoid a kid who ran into the street from between two parked cars?

Answer: you were going too fast to begin with. If you're travelling anywhere that this is a possibility, your maximum speed should be less than 20mph. A collision at that speed is almost never fatal. That speed also allows almost instant braking.

The fact that autonomous cars will be driving so slow and defensively in the suburbs will perhaps be the biggest cause for the coming backlash against them.

[raisedbyninjas]

We're talking about exceptional circumstances. With hundreds of millions of autonomous vehicles on the road, 1 in a billion is next Tuesday. We can minimize the need for this decision, but leaving the behavior undefined will just lead to headaches when it does happen.

[bryanlarsen]

We have currently ~30,000 fatalities in a year. What portion of these are trolley problems? Less than 1 in a million, I'd bet. What percentage of those trolley problems are entirely avoidable through proper defensive driving techniques?