Will Autonomous Vehicles Be Able to Break the Speed Limit?

Gunning it on an open road, regardless of the rules, offers a certain thrill. But will robots think so, too? Marin Tomas/Getty Images

Imagine a future in which you climb into the back of your self-driving autonomous vehicle and instruct it to take you on a late-night fast-food run. Imagine also that you're particularly famished that night. Will you be able to tell the robot driver to exceed the posted speed limit to get you to the drive-through window a little more quickly? Or will the robot remind you in a polite but firm synthesized voice that you had to obey traffic laws?

That's a hard question to answer, since level 5 autonomous vehicles — the most autonomous ones equipped to be able to drive in any sort of environment, with no human intervention — are still somewhere way off in the future. But it seems likely that when robotic cars hit the market, they'll be designed to stick to speed limits, except perhaps when safety requires speeding up.


A few years back, when experimental autonomous vehicles, or AVs, first began appearing on American roads, Reuters reported that Google's self-driving cars actually were designed to go up to 10 miles (16 kilometers) faster than the speed limit, when traffic conditions made it necessary. The problem wasn't that the robots get impatient, but rather that human drivers routinely exceed the posted speed limit, and tend to go as fast as they think they can get away with, without getting a ticket. Researchers worried that with all those humans out there careening around madly, it might be dangerous for robots to plod along at the legal limit or lower.

But so far, there aren't any signs that AVs are prone to speeding. In California, the only state that keeps track of accidents involving autonomous vehicles, there have been nearly 50 mishaps reported since 2014. In many of them, it was a human-driven vehicle that rear-ended an AV, often when the robot cautiously slowed to yield to another car or a pedestrian. In other instances, human drivers got frustrated with slow-poke AVs and clipped them as they tried to pass.

According to a 2017 report on speed limits by the National Conference of State Legislatures, government traffic planners envision a future in which AVs most likely will be programmed to not exceed the posted speed limit in an area. Moreover, they're hoping that regimentation will make the roads safer, because it will reduce the danger that develops when the roads are filled with vehicles traveling at varying rates of speed. On the downside, the authors note, a proliferation of law-abiding robots will mean a reduction in the revenue that local and state governments have been getting from ticketing speeders.

But if we ever get to the point where we have enough AVs on the road that we could have robot-only highway routes, networked AVs might be able to travel safely at higher speeds than human drivers. The tech-focused venture capital firm Madrona created a 2017 study envisioning the conversion of U.S. Interstate 5 in the Pacific Northwest into an AV-only road.