NASHVILLE, Tenn. (AP) — As millions of people travel the interstates this Thanksgiving, many will encounter patches of stopped traffic for no apparent reason — no construction or accidents. Researchers say the problem is you.
Human drivers simply don’t do a good job of navigating heavy traffic conditions, but an artificial intelligence experiment in Nashville last week means help could be on the way. In the experiment, specially equipped cars were able to ease rush hour congestion on Interstate 24, researcher Daniel Work said Tuesday. In addition to reducing driver frustration, Work said less driving without stopping means more fuel savings and, by extension, less pollution.
The Vanderbilt University professor of civil and environmental engineering is part of a group of engineers and mathematicians from universities across the US who have been studying the problem of phantom traffic jams after a simple experiment in Japan a dozen years ago he showed how they develop. The researchers put about 20 human drivers on a circular track and asked them to drive at a constant speed. In no time, the traffic went from a smooth flow to a series of stops and starts.
“Phantom traffic jams are created by drivers like you and me,” Work explained.
A person hits the brakes for any reason. The person behind takes a second to react and has to brake even harder. The next person has to brake even harder. The wave of braking continues until many cars are at a standstill. Then, as traffic clears, drivers accelerate too quickly, causing more braking and another jam.
“We know that a car braking suddenly can have a huge impact,” Work said.
Last week’s experiment showed that a few cars driving slowly and steadily could also make an impact, for the better.
The experiment used 100 cars traveling in loops on a 15-mile section of I-24 from 6 a.m. to 9:45 a.m. each morning. Based on the premise that if 5% of the cars on the road acted together, they could reduce the prevalence of phantom traffic jams, the researchers equipped these 100 cars to communicate wirelessly, sending traffic information back and forth. comeback
They also took advantage of the adaptive cruise control that is already an option on many new vehicles. This technology allows the driver to set a car to cruise at a set speed, but the car automatically slows down and accelerates as needed to maintain a safe distance from the car in front. In the experiment, the adaptive cruise control was modified to react to the overall flow of traffic, including what was happening far ahead, using artificial intelligence.
The cars’ decision-making occurred on two levels, Work said. At the cloud level, information about traffic conditions was used to create a global speed plan. That plan was then relayed to the cars, which used artificial intelligence algorithms to determine the best action to take. Researchers were able to assess the effect connected cars had on morning traffic flow using a special 4-mile stretch of I-24 equipped with 300 pole-mounted sensors.
The experiment is a project of the CIRCLES Consortium, a group that includes several automakers and the US Departments of Energy and Transportation. Other principal investigators are based at the University of California, Berkeley; Temple University; and Rutgers University-Camden.
Liam Pedersen is the assistant general manager of research at Nissan, a CIRCLES consortium partner who was in Nashville last week for the experiment. He said one of the exciting things is that it builds on technology that is already in many new cars.
“This is not self-driving,” he said. “That’s something we could realize very soon.”
Asked if automakers would be willing to cooperate to ease traffic, Pedersen said, “I certainly hope so, because the system works best when lots and lots of cars are involved.”
Last week’s experiment was based on work he and his colleagues conducted in 2017 at the University of Arizona. This repeated the Japanese experiment, this time with a single self-driving car thrown into the mix. The autonomous car smooth the flow of traffic so there was 98% less braking. This resulted in a 40% increase in fuel efficiency and a 14% increase in distance traveled.
Researchers are still crunching the numbers from last week’s experiment, but Work said it “showed that these traffic jams can be reduced using the new automated vehicle technologies that we’ve developed. There’s no question that automotive technology improved can significantly reduce ghost traffic congestion when implemented at scale.”
Still, he cautioned that the technology won’t suddenly eliminate congestion.
“When there are more cars on the road than the road can handle, there will always be traffic,” he said. “But this can make that congestion less painful.”
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