At 40 mph 1.3 seconds is 76 feet, right around the threshold of stopping distance if the computer slammed on the brakes at that moment. At the very least, it's the difference between an ER visit and a fatality. Far too short a time for a human to react to a warning, though.

> Far too short a time for a human to react to a warning, though.

Simply swerving left would have avoided the accident. Stopping is not the only thing the human driver could have done!

Sure. What I mean is that if they expect to correct this with some kind of "oh shit" alarm for the driver, 1.3 seconds isn't enough time to do anything helpful.

The whole thing is nuts. Imagine a human driver seeing the same thing the computer did, and responding the same way: they'd be in handcuffs.

Average reaction time for humans for a visual alarm is 1/4 second. So more than a second left. And that's a second at the current speed. At 60 mph (was that the speed?), that's about 25 meters. With 1 g breaking for 1 s, the car's speed could have been reduced to 27 mph, and the person on the street would have had almost 0.4s more time to jump away, alerted by the sound of the car breaking.

Reaction time is only part of the picture. First you recognize the issue. Then you have to move your body. In court they generally use 1.5 seconds for all of this. Your best case is .7 seconds, but this situation was clearly not the best case - even if the human had been paying attention it would be much worse.

http://www.visualexpert.com/Resources/reactiontime.html has a good discussion (starting with why 1.5 seconds is not the answer)