As closely as I've followed the development of autonomous vehicles over the past few years, it somehow never occurred to me that they'd have to know when to honk, too. (As long as they're sharing the road with human drivers, anyway.) Turns out Google has started thinking about it recently.
In the latest monthly report on its self-driving car program, Google reveals that it's been training the cars to honk at the absent-minded humans around them when the situation demands. And they even honk differently depending on what's going on: "We've even taught our vehicles to use different types of honks depending on the situation," the report reads. "If another vehicle is slowly reversing towards us, we might sound two short, quieter pips as a friendly heads up to let the driver know we're behind. However, if there's a situation that requires more urgency, we'll use one loud sustained honk."
But you can't just flip a switch and let a robot car start honking at people. Google says that it first only honked the horn inside the cabin, so test drivers could observe the situation and note whether a honk was actually appropriate or not. Ironically, actual human drivers mostly honk at completely inappropriate times — at least here in New York City — so a polite, considered beep from a self-driving car would be a welcome improvement.