Hacker Traffic Havoc: Stalled Autonomous Cars and City-wide Gridlock 

Another potential source of skepticism about self-driving cars has cropped up, one that the auto industry may need to quell in the public mind: a new report depicts hackers causing autonomous vehicle (AV)-driven gridlock tying up entire parts of cities. And it wouldn’t be very difficult: it’s a matter of randomly stranding a portion of internet-connected cars at strategic intersections.

In the report, released this week and called “Cyberphysical Risks of Hacked Internet-Connected Vehicles,” researchers* at Georgia Tech and MultiScale Systems stated that their intent was to expand the scope of discussion regarding automotive cybersecurity, which has typically examined how hackers could cause car crashes or use cars to hit pedestrians. The researchers “warn that even with increasingly tighter cyber defenses, the amount of data breached has soared in the past four years, but objects becoming hackable can convert the rising cyber threat into a potential physical menace.”

“With cars, one of the worrying things is that currently there is effectively one central computing system, and a lot runs through it,” said Jesse Silverberg, president of Multiscale Systems and co-leader of the study with Peter Yunker, Georgia Tech assistant professor. “You don’t necessarily have separate systems to run your car and run your satellite radio. If you can get into one, you may be able to get into the other.”

The research team ran hacking simulations internet-connected cars in Manhattan and report they could cause major disruption or actually freeze traffic, bringing the borough nearly to a standstill.

“Randomly stalling 20 percent of cars during rush hour would mean total traffic freeze,” said David Yanni, a graduate research assistant. “At 20 percent, the city has been broken up into small islands, where you may be able to inch around a few blocks, but no one would be able to move across town,”

Hackers could cause major problems even if only a portion of cars are internet-connected AVs. The researchers determined that if 20 percent of all cars on the road are stalled, general gridlock will result. So if 40 percent of all cars on the road were connected, hacking half of them would cause havoc.

Hacking half as many of all cars at rush hour, the researchers report, would cause enough congestion to block emergency vehicles from getting through traffic quickly. In intermediate daytime traffic conditions, the same would happen with a 20 percent hack.

Ironically, as densely populated as Manhattan is, hackers could find more fertile ground for chaos in other cities.

“Manhattan has a nice grid, and that makes traffic more efficient,” said Yunker. “Looking at cities without large grids, like Atlanta, Boston, or Los Angeles, and we think hackers could do worse harm because a grid makes you more robust with redundancies to get to the same places down many different routes.” (This writer can attest that Boston frequently experiences traffic surpassing a hacker’s wildest dreams.)

While the researchers stated they are not cybersecurity experts, they offered ideas of reducing the risk of AV hacks.

“Split up the digital network influencing the cars to make it impossible to access too many cars through one network,” said lead author Skanka Vivek, a postdoctoral researcher. “If you could also make sure that cars next to each other can’t be hacked at the same time that would decrease the risk of them blocking off traffic together.”

The Manhattan simulations came out of Yunker’s research in “soft matter physics,” which looks at “how constituent parts – in this case, connected cars – act as one whole physical phenomenon.” Car movement was analyzed on streets with different numbers of lanes and included how cars, handled by humans or machines, get around stalled vehicles.

“Whether traffic is halted or not can be explained by classic percolation theory used in many different fields of physics and mathematics,” Yunker said.

Alarming as the AV hack could be, the researchers said their findings did not include such factors as the ensuing public panic or car passengers leaving vehicles and becoming pedestrians, making gridlocks worse.

“I want to emphasize that we only considered static situations – if roads are blocked or not blocked,” Yunker said. “In many cases, blocked roads spill over traffic into other roads, which we also did not include. If we were to factor in these other things, the number of cars you’d have to stall would likely drop down significantly.”

*Skanda Vivek, David Yanni, Peter J. Yunker, and Jesse L. Silverberg