Self-Driving Cars

By Sean Carroll | October 14, 2008 10:25 am

On a recent trip, with my car in cruise control, I noticed something interesting: if the car in front of me slowed down, my car would slow down along with it. Apparently it’s equipped with proximity sensors in the front and back, which serve to protect against lazy drivers who hit cruise control and then start reading email on their iPhones while zooming down the highway. (Not me!) Which is great, but I couldn’t help but imagine the obvious next step: once you have cruise control and the ability to adjust to the speed of traffic, not to mention cars that park themselves, you are most of the way to self-driving cars.

You will be unsurprised to learn that I’m not the first to think of this. Tim Lee has written an interesting introduction to the state of the art, as well as speculations on what the effect of automatic driving would have on urban cityscapes. (Via Yglesias.) A big one: parking is incredibly resource-intensive, but if your car can drive away and wait for you at some central location, vast stretches of land can be returned to human uses rather than automotive uses.

Will we have self-driving cars within the next few decades? I don’t think it’s such a leap, given what technology is already available — and that technology can be confined to the cars themselves, there is no need to put rails down or any such thing. There is even a sensible phase-in strategy, where we convert present-day carpool lanes into automated-driving lanes. But Atrios is skeptical:

I think self-driving cars are going to be here some time after flying cars, my jetpack, and Glenn Reynolds’ sexbots, but this little thought experiment is useful for highlighting that while we talk about highways and roads and whatnot, the biggest problem with cars generally is parking. They take up space. Lots of it. That space reduces density most places, and reduces the benefits of density in places where it exists.

Concerning flying cars and jetpacks, I’m likewise pessimistic (at least sometimes). But those sexbots are on the way. And they’ll be arriving in self-driving cars.

  • Speedy Gonzalez

    Well, we already have Self-Driving Laptops. What are they waiting for…? πŸ˜‰

  • B

    definitely not. too much security problems. ask yourself why people are afraid of flying but not of driving? one reason is because they want to be in control.

  • Jon

    I don’t think your cruise control is meant to protect against lazy drivers. It is very frustrating when your cruise control is set to 70 and the car in front of you drives somewhere between 69 and 70. This usually happens when the speed limit is 65 and each car is trying to drive 5 over the limit. I often wished for automatic sensing in my cruise control at such times, which occur too frequently for me to bother even using cruise control, especially during long road trips.

  • TimG

    Given how many more Americans die in car crashes than from, say, terrorist attacks, isn’t this something we should be devoting more of our resources to pursuing? (I’m presuming, of course, that automated driving would be safer than what we do now.) About 42,000 Americans die every year in car crashes — that’s 14 September 11th’s per year.

  • teadrinker


    I want a sexbot.

    I don’t care about flying cars or anything else.

  • Sarah

    Cruise control is a great thing. Mine is accurate enough I can thumb it up or down 1mph at a time. If every car were on cruise, we could have much better “packing” at high density traffic flows. Stop & Go waves begin with small decelerations that are amplified into wavelike behavior ( from particulate cars! Some cool simulations have been done ) and they’d go away.

    Sexbots? Ewwwwww. Not even if it gets me into the carpool lane.

  • delzoup

    Here’s your flying car maker…

  • rob

    as soon as we have cars that can drive themselves, there will be a virus written that will hijack control of your car and take you to the nearest fast food drive thru. of course, the corporations will deny they had anything to do with it.

  • Pieter Kok

    I can just imagine the early models of the sexbot going horribly wrong. Think of Robocop, but more… intimate.

  • Jesse

    I really don’t think this is too far off.

    I can actually imagine a time 40-50 years from now where it might actually be illegal to drive manually in certain areas. There are so many potential benefits to letting cars, with optical and communications systems that are constantly talking to each other and course-adjusting, do the driving instead since a human being will never be as conscious of the traffic conditions as a car communicating with a grid would be.

  • Lab Lemming

    I reckon they will be standard in Asia 10 years from now, common in Europe in 15, and outlawed in America.

    Some remote mines are starting to use pilotless construction machinery, and the benefits in terms of mechanical wear and tear are astounding.

  • Elliot Tarabour


    Are you referring to the self driving cars or the sexbots?


  • Elliot Tarabour

    Wow a whole generation of new jokes.

    …a man walks into a bar with a sexbot on each arm….


  • George Musser

    The Japanese version of the Prius will automatically parallel-park.

  • Lab Lemming


  • Sam Gralla

    On the flying car thing, you might be interested in my brother-in-law’s startup,

  • Eugene

    Great, in 15 years now, girlfriends/boyfriends will be obsolete.

    /can’t wait.

  • Speedy Gonzalez


    McCain walks into a bar with an earmarked sexbot glued on to each ear. The bartender whispers, “Hey, your wife is here…” McCain screams, “SORRY, CAN’T HEAR YOU!”


    (Those who want to kill me can do so in the cafeteria on Mondays to Thursdays after 4.30 p.m., except Wednesdays when I do yoga)

  • Elliot


    can’t wait to hear about the astounding benefits of the sexbots on “mechanical wear and tear”.


  • David McMahon

    I actually like driving. I like getting out on a curvy road in the mountains and really driving the vehicle. Riding a motorcycle is even better.

    I am not some luddite, but I actually find this idea a bit distasteful. I don’t want a computer doing every last thing for me. And we are going to be so lame we can’t even park a car? A computer has to do it for us?

    One area where this could benefit though, is drunk people could have their own cars take them home on autopilot.

  • David McMahon

    WOW envisioning a future where it would be illegal to manually drive cars. Aren’t there too many laws already? I think so many laws have been made that we really don’t have “freedom” in the United States anymore. My stupid mayor controls when I can water my lawn, what my dog food bowls have to be made out of, and an endless litany of other ridiculous minute controls over daily life. Is that why the west was won so government bureaucrats could tell us when to water our lawns? Instead of making it illegal to drive cars in certain areas, I think they should cut down on the number of traffic lights in cities so that traffic would move more smoothly. I know governments often mean well (reducing water use in the desert say) but there is way too much government control already. Its very easy to make new laws and city ordinances. Pretty soon you will have to ask the government permission to leave the house.

  • David McMahon

    How is having your car drive away and wait for you at a “central location” going to reduce land devoted to cars? Is the central location your house? What good would that be? So I’d have to sit there wherever I was and wait for my self-driving car to come and pick me up. Seems kind of self-defeating. Why not take a bus instead?

    What other central location did you have in mind? A parking lot for automated cars? Assuming the same number of people would be on the road won’t the same amount of space be required for all those waiting cars for people at the mall? Here is a better suggestion: population control. If there were fewer people, a lot of “issues” would go away.

  • Ijon Tichy

    When highly sophisticated sexbots become a reality, either of the following will happen:

    1) Laws will be passed to make them illegal.
    2) Men will become sexually liberated.

    Cars will hopefully be replaced by public transport, and therefore cities will once again be designed for people.

  • jick

    A mature technology already exists that allows your car to drive away and wait for you at some central location.

    It’s called Public Transportation System.

    Okay, a subway train (or even a taxi) is not exactly “your car”, but when you live in urban area, in a planet with huge carbon oxide problems, you have to make some compromise. It’s a shame that many governments will rather invest on building more roads for 1-driver-no-passenger cars, instead of building a better public transportation service.

  • jick

    Oh, oh, of course, I meant carbon dioxide. How embarrassing… :(

    (Carefully checks spelling again…)

  • monk.e.boy

    I heard on the radio that over 70s are more dangerous behind the wheel than drunk drivers.

    But the over 70s vote in droves, the politician they had in to talk about it laughed a lot and said he’d have bus loads of wrinklies petitioning outside his office for the next month πŸ˜‰

    I’d like a computer to control my car. I fear other drivers due to their complete stupidity.

  • monk.e.boy

    >> Okay, a subway train (or even a taxi) is not exactly “your car”,

    Good god, look at the results. Urbanites use trains a little, but 99% of people don’t. Please, dear god, stop using this argument.

    When I drive home I go to the shops, check the surf, pop into my mates house. Take some photos of the sunset…. how the hell does the train let me do that?!?

    99% of people don’t have a life that fits around a fixed train time table. Get over it. Trains don’t work.

  • Lab Lemming

    “When highly sophisticated sexbots become a reality…”

    I don’t think the big bucks are in the sophisticated end of the market. Ditto with the mechanical wear and tear.

  • Chase

    But will an automatically-controlled car be able to respond appropriately when a deer or dog wanders on to the highway, or if being used in cities to go to parking, if a child does?

    Trains still have drivers, and I think it is for this reason. And trains face this type of problem much less often than cars (and are much less able to respond, but….).

  • Invader Xan

    On cars and jetpacks… Minority report, anyone? πŸ˜‰

  • The Almighty Bob

    Self-driving cars are not ‘possible,’ or ‘feasible’ – they’re ready, and have been for a while. Issues of liability has kept the technology from deployment.

  • Dae Gregoire

    Larry Niven long ago wrote about the consequences of flying cars. Imagine a 15 (flying) car pile up – over your head. Who needs killer asteroids? In Niven’s “known space” it was illegal, in fact it was a capital offense to drive a flying car over an inhabited area under manual control. The rational for the severity of the punishment was to fill the organ banks, but considering some of the things I seen people do while driving an earth bound car and the likelihood of catastrophic accidents, I’m not sure the penalty would be excessive.


  • Speedy Gonzalez

    Chase, “Trains still have drivers”

    Not everywhere, the Copenhagen Metro has trains that are driver-less and run entirely by a computer system called ATC (Automatic Train Control).

  • Sili

    Nope. Never.

    Drivers drive cars because they’re crazy individualists. And of course we all know that most drivers consider themselves better than average.

    They’re never gonna give up control.

    Sure it could easily be implemented, but the market won’t be there for it.

    At least not in the US as said by LabLemming. I can’t even imagine it here in Denmark.

    Sad. But true.

  • NeatoPrsn

    Isn’t it kind of silly to assume this would be an over night thing? Why wouldn’t it come in the form of a feature of cars and then eventually be as common cruise control, radios, and air conditioning after that point it’s just another hop, skip, and a jump to being legally required.

    People wll get used to having it, use it liberally and we’d figure out oh, we are safer in general this way. Can you imagine the efficiency increase?

    I’m a car enthusiest and I too love sitting behind the wheel but don’t tell me a majority of people would not be better off with automated cars.

  • tyler

    nice Niven quote there above. Larry gets ignored a lot these days, partly for his highly unfashionable politics (with which I vehemently disagree). But when it comes down to the mark of a great futurist scifi writer – how many of the things he wrote about are now current real issues – I think he might have the highest score of any writer. The Gil the Arm stuff on organlegging is prescient beyond belief, and it’s far from the only thing…

    Biggest problem with automated driving is emergent mass behavior, of course. When you have large numbers of autonomous agents following simple rules en masse, big things happen, and not always what you’d expect. It’s true enough of human traffic patterns (seen the paper on shockwave modelling of traffic jams? great stuff) that when you turn the agents into robots, I would expect some rather….interesting behavior to emerge.

    lol actually I just had an image of The Game of Life being recreated in traffic patterns as seen from overhead, with repeating structures cascading across the grid, etc.

  • Quasar9

    “Parking is incredibly resource-intensive, but if your car can drive away and wait for you at some central location …”

    At last trying to put thinking and technologyinto some ‘practical’ use. But Why have the car wait for you at some central location.
    If I could go down the pub, restaurant, club or airport, be dropped off by the car which either selects the nearest parking space (or returns home to my garage) and then comes and picks me up – Great! No need for the wife to go teetotal on a night out.

    Mind you I don’t think Taxi Drivers or Limo Drivers would be too happy. Yet another redundant career?

  • Matt Springer

    Geez, #22, fascist much? Self-driving cars would solve the problem pretty easily – they drop you off and go somehwere where there’s plenty of room – say, a huge parking garage on the outskirts of town. It comes back and picks you up when you’re done. The total footprint would be vastly small than many numerous lots and garages distributed everywhere. You’d need electric cars charged by nuclear/renewable power or something similar to prevent additional pollution. But all things considered it’s a vast improvement on the status quo.

  • sonic

    I think people will continue to enjoy driving themselves. We can’t automate ourselves out of existence- can we?
    Of course I can see the need for a self-driving car if you are with your sex-bot.

  • bane

    Assuming you define a “self-driving car” as a car that drives itself under almost all conditions (in the city, in the suburbs, in the narrow lanes from another century, not just on the freeway), then it’s going to be doing it using a substantial amount of image processing (even if you use something like laser sensing, when it’s dense enough it’s essentially an image you’re dealing with).

    I work in image processing and my professional opinion is: IF we could outlaw humans driving (and really get it enforced), then twenty/twenty-five years we could get it developed and deployed (deployment actually takes much longer than you’d think, so twenty years is “right around the corner”). IF we can’t outlaw human driving then I’d put it at least at the forty year mark. The reason for this is the “New York cabbie problem”: everyone who drives in New York knows that New York cabbies do truly insane things, so upon seeing a yellow cab they hang back a little to deal with problems. But the cabbie’s know this, so they know there are maneuvers they can pull using this knowledge, and push things as much as they can without getting attention from the police. The cabbie’s actively use the way that people view them to increase their driving options.

    In the context of self-driving cars, if there are no human drivers then you can assume that other cars will either behave sensibly or they’re malfunctioning and will be behaving “randomly”. This is a hard, but do-able problem. What they aren’t going to do is try and take advantage of the fact that a program, designed to avoid killings, injuries and other damages, is driving the car. But if there are also human drivings, some of them will decide “since that self-driving car should be able to respond quickly in order to avoid a crash, I’ll cut in front with minimal clearance”. Likewise the envelope of various other “self-centred” driving techniques will get pushed right to the edge. Since just a few deaths that appear to be caused by self-driving cars will cause a backlash, any companies that want to deploy them will need to have the controlling programs completely capable of dealing with an intelligent and actively “hostile” other human drivers whilst still giving a reasonable ride. (If the car emergency stops every five minutes to avoid a human gaming the system it’s not something people will pay for.) This is a much harder problem (indeed the 40 years incorporates a guess of increasing “artificial intelligence” productivity as the years go by, it’s a more than twice as difficult problem.)

    I’d actually expect things like surgical robots and robots for helping the elderly to be deployed sooner than self-driving cars precisely because you can safely assume all the humans involved will be co-operating rather than gaming the system.

  • Michael

    Unfortunately, as The Almighty Bob pointed out, the issue that will stop self-driving cars from becomming commonplace is liability. This is especially important in a country that is now practically built on a foundation of litigation, such as the United States.

    Think about it: if your automatic car crashes into a bus full of catholic schoolgirls and nuns, killing them all in a horrible fireball, who is at fault? There is no way the car companies will want to wear that kind of publicity or liability.

    Speaking of publicity… TimG points out that about 42 thousand Americans die each year in car crashes. If we assume that the first iteration of self-driving cars aren’t perfect and te death toll is reduced to about 20 thousand, which headline will sell more papers?

    “Self-Driving Cars Cut Death Toll in Half”
    “Phycho Robot Cars Kill 20 Thousand”

  • David McMahon

    Hi Matt,
    Having the cars go to a parking garage on the edge of town seems silly. As it is now, if I want to go to Borders I can park right outside. So when I am browsing books and the mood suits me to leave, I just walk out and get my car. So why would I want a self driving car parked at the edge of town? I would have to ping it when ready and then sit there and wait 20 minutes for the thing to show up. Sounds like a pain in the butt. In any case I still don’t see how its going to reduce space used for cars. If the same number of people are at the mall, their self-driving cars are going to take up the same amount of space as their manual cars do now.


  • John R Ramsden

    Sean wrote “Concerning flying cars and jetpacks, I’m likewise pessimistic (at least sometimes). But those sexbots are on the way ..”

    Yes, I have my eye on one of these little beauts, although it’s hard to judge the exact scale.

    Presumably the strange looking pedal-like assembly underneath is some kind of advanced retractable landing gear.


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About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] .


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