Submitted by Michael Frankfort
A Simple Math Equation Could Solve Highway Traffic Jams Forever
Who needs self-driving cars? Unnecessary traffic jams might be caused by human’s innate inability to drive so well, but one MIT computer scientist says there’s an algorithm for that.
Traffic, one of the most annoying conditions of modern life (if you own a car), often happens for no real reason. Roads have carrying capacities, sure, but even drivers on closed tracks have shown that traffic jams appear to be hardwired in human nature.
Horn explains that drivers unconsciously follow an equation in their heads: Look at the car ahead, try to maintain a safe distance. If it’s larger, accelerate, and if it’s shorter, brake.
“This modified system, which I call bilateral control, uses information from vehicle behind you,” Horn says. “You try to maintain the same distance ahead as behind you. Think of the car connected in front by string, and distance in car behind is the same.”
But how might all cars make the shift? Many cars already have rearview cameras, and high-end vehicles have something called adaptive cruise control. Together, Horn says that same system could easily accommodate his bilateral algorithm.
The flow only really works if all cars do it–but nothing is lost if one car abides by the rules and others don’t. “For a while I was collecting GPS data in my own commuting to support this research,” Horn says. “I found at some point I had kind of unconsciously adapted my driving modes myself, and had smoothed out some of these oscillations.”
“It’s well-known that smoother traffic flow would lead to lower emission rates in general. More stop and go traffic results in a higher emission rate,” says Greg Rowangould, an assistant professor of civil engineering at the University of New Mexico who researches the impact of traffic pollution. Rowangould also points out that this system could one day be less expensive than adding a lane to a highway to relieve congestion.
Still, Rowangould says that bettering congestion can be tricky, and sometimes can have the opposite effect. “When you relieve congestion, you get to where you’re going more quickly, and that reduction in traffic time tends to attract more cars to the roadway,” he says.
There’s only one way to find out, and that’s to test it. Horn is currently in talks with interested parties in China (he wouldn’t say who), to try out his bilateral control system on a closed track.
Horn acknowledges that convincing people that looking behind them while driving is just as important as looking ahead will also be a challenge.
“I’ve really encountered quite a bit of skepticism. I mean, why on Earth would you want to look behind you?” Horn says. “Once you see the solution, it’s like a magician who’s explained the trick and it becomes obvious.”