Google now has software designed to help it detect school busses.

Robot Rage? Google Teaches Its Self-Driving Cars How To Honk At Distracted Drivers

Depending on where you live in the world, the humble car horn can have lots of different meanings.

Officially — at least in most of Europe and North America — sounding your car horn is intended to be a last-resort way to warn other road users of your presence, such as rounding a blind corner on a narrow, single-track country lane in rural Somerset or making a distracted driver who is veering from their lane on the freeway aware of your presence.

Google has taught its cars to honk their horns.

Google has taught its cars to honk their horns.

The real world is rarely quite clear cut, and usually pairs the sound of a horn with anger.

There are exceptions. In India for example, drivers have used their car horns for years to indicate to trucks that they intend to (or ar in the process of) overtaking. And while the Indian Government has been working in recent years to ban trucks from carrying the “Honk OK Please” on their tailgates — the sign thought to have started the Indian love affair with the car horn — honking horns are a part of every single rush hour.

Horn sounding is an integral part of Google's training.

Horn sounding is an integral part of Google’s training.

Then there’s New York City, its crowded streets, and the expectation from every driver on the city’s streets that sounding one’s horn in frustration will clear a traffic jam more quickly. And that’s before you even get to the UK, where the sound of a horn has been historically and culturally (though not legally) used to say goodbye to friends and family departing after a visit or  a quick hello (accompanied by a wave from the driver) when passing someone you know.

All too often however, the horn is used for a different purpose: to let another road user know you’re pissed at whatever stupid thing they just did. And that, as we all know, can lead to road rage covering the whole spectrum from an angry flipping of the bird through to shouting, swearing, and even physical violence. Even when the horn is used for the purpose for which it was intended — that polite “hey, I’m here!” warning to other road users — road rage can often be not far away.

Given how inflammatory the use of a car horn can be — not to mention how hard some countries work to actively discourage horn use, slapping fines on anyone who misuses theirs — you’d be forgiven for thinking that any company developing a self-driving car would steer clear of any use of the humble two-tone horn. After all, autonomous cars can react far more quickly than the average human to a road hazard. They’re designed to preempt behavior and take defensive action that roughly follows the Three Laws of Robotics. They are trained to learn from their mistakes, identify hazards, and communicate with other autonomous cars across a vast artificial neural network that lets every car learn from every experience.

In such a context, horns might seem unnecessary.

Autonomous cars can react quickly to danger -- but they need to better communicate with the rest of the world.

Autonomous cars can react quickly to danger — but they need to better communicate with the rest of the world.

Yet as Google detailed in its May Self Driving car report (via ArsTechnia), software giant Alphabet (previously known as Google) is teaching its autonomous Lexus Hybrids, Toyota Prii and Self-Driving low-speed Google pod electric cars on when and how to use the horn.

It’s all part of an ongoing attempt to make its self-driving cars a little more… human in their actions on the road. And that’s not because Google intends its autonomous vehicles to pick up the bad driving habits we all have: it’s to help them interact more smoothly with other users.

That process started several years ago, when Google announced that it was going to make its self-driving cars more aggressive when it came to intersections. Originally, Google’s software had resulted in autonomous vehicles which were simply too cautious and hesitant to exist alongside other cars on the road. While they may have been obeying the rules of the road, Google’s autonomous vehicles were simply being taken advantage of by more aggressive, more decisive drivers.

The announcement over horn use is in a similar vein. Instead of relying on its software to stop autonomous cars dead in their tracks if there’s a hazard ahead, Google’s new software plans a more proactive, human approach: react to dangerous or distracted driving with a short, polite honk.

Eventually, all of Google's cars will start honking.

Eventually, all of Google’s cars will start honking.

Take the example of someone backing out onto a residential street from their garage and not paying attention to cross-flow traffic, for example. Using Google’s old software, its self-driving cars would have identified the hazard, then taken appropriate action such as swerving or stopping. Now, Google cars have another option: sounding their horn, alerting the driver of the other car to their presence and hopefully allowing the car with the right of way the ability to continue unhindered.

Does this mean we’ll see a whole host of honking self-driving cars? Or a mass of new road rage incidents prompted by a software algorithm letting the wrong driver know they screwed up that last intersection?  Not quite.

“The human act of honking may be (performance) art, but our self-driving cars aim to be polite, considerate, and only honk when it makes driving safer for everyone,” Google says in its report. Over the past few months, Google reports that it has been testing a prototype algorithm for a horn alert, sounding a buzzer inside rather than outside the car. The job of its engineers meanwhile has been to either note the software-initiated noise as appropriate or inappropriate, allowing Google’s software to better learn when is a good time to sound its horn and when it isn’t.

“As our honking algorithms improved, we’ve begun broadcasting our car horn to the world. We’ve even taught our vehicles to use different types of honks depending on the situation,” Google continues in its report. “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.

Will other autonomous cars follow suit? Probably: it makes total sense for them to honk like humans.

Will other autonomous cars follow suit? Probably: it makes total sense for them to honk like humans.

“Our goal is to teach our cars to honk like a patient, seasoned driver. As we become more experienced honkers, we hope our cars will also be able to predict how other drivers respond to a beep in different situations,” it continued.

It’s easy to conclude from Google’s decision to introduce the use of horn that autonomous cars aren’t ready for the real world. But in reality, it’s us — the humans that interact with autonomous vehicles — who aren’t ready. In an ideal world, a driverless, autonomous car shouldn’t need to honk at other road users to announce its presence, because either everyone else will be paying attention or be in an autonomous vehicle themselves.

Sadly, the world isn’t perfect. And so, even our robots have to learn to honk like a pro.


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  • Martin Lacey

    Good old Google, sounding their media horn to remind us that they are still testing their own autonomous system.

    Will it ever get to real world use and beyond their test mules?

    • KIMS

      I’m fairly convinced it will, though probably first in more corporate settings (meaning, companies deploying freight or mass transport solutions using their system.)

      Considering the amount of these ‘mules’ driving around doing mapping updates etc., it seems a bit harsh to exclude that from ‘real world use’, it clearly is already serving a real world use, albeit one that for the time being is limited to “real world use for Google”. 🙂

      Anyways, barring any utter catastrophes slowing things down, or complete regulatory grid-lock, I would expect high-end luxury cars to be at level 4 and flirt with level 5 within the next 10 to 15 years, and at level 5 as a ‘standard’ feature within the next 15 to 20 years. I would expect “upper middle class” car’s to lag that by about 5 years, and from that extrapolate that a significant proportion of all cars on the roads in the next 20 to 30 years will be level 4 or higher (as older cars start trickling into the used car markets and the feature continue to make its way into the cheaper product lines). I’m pretty sure Alphabet/Google will be a part of that journey, side by side with a slew of other companies.

  • Charlie Payne

    How long before Google installs a robotic finger so their cars can flip-off other drivers? “YO! TESLA! I’M DRIVIN’ HERE!” 🙂

  • Charlie Payne

    I’m reminded of the Futurama episode, “The Honking”… “Ed Begley, Jr.’s electric motor, the most evil propulsion system ever conceived!”

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