Will Self-Driving Cars Help Reduce Traffic Jams?

The promise of automated cars is that they could eliminate human-error accidents and potentially enable more efficient use of roadways. That could mean traffic reduction and lower commute times.

The Defensive Delay. One of the reasons traffic jams exist in the first place is due to our (understandable) behavior of waiting for the car in front to start accelerating. No matter what the cause of the initial stop or slow-down was, the ripple effect which creates the jam then has to release its tension one car at a time. The traffic jam continues to exist even though there is nothing preventing anyone's forward movement. If you're the 20th car in a line of stopped cars, you don't start moving until after the 19th car does. The 20th car waits for 19 discrete actions to occur consecutively before it can begin to move.

While autonomous cars may not fully marginalize this pattern – if for nothing more than the sake of trying to behave more human-like to keep people comfortable – their connectivity will certainly allow them to behave in a manner closer to a road train, wherein the 20th vehicle in a traffic line can start moving at the same time the 1st vehicle does. The reality is that the only thing stopping everyone from moving at the same time is their lack of faith in the person ahead.

Latest Developments. By combining several technologies that exist today, Ford says cars will soon help unclog traffic jams more efficiently than human drivers can. The concept, called Traffic Jam Assist, will use adaptive cruise control, lane keep assist, and sensors from active park assist to keep traffic flowing efficiently and safely. In fact, safety is perhaps the biggest benefit to self-driving car systems, which can neither drive aggressively nor be distracted the way human drivers are. Another automatic driving tool, developed by Volvo and called City Safety, stops cars in potential accident situations on urban roads.

In addition to clearing the roads of human driving errors, automated navigation systems will reduce gasoline consumption as well as driving times. "If one in four cars has Traffic Jam Assist or similar self-driving technologies, travel times are reduced by 37.5% and delays are reduced by 20%. That’s because adaptive cruise control (ACC) is better at pacing the car ahead without continual brake, speed-up, brake cycles."

New Research. New research shows that adding just a few self-driving cars to the streets can improve overall traffic patterns. In the next several years, there will likely be an awkward transitional period when human drivers and autonomous vehicles share the roads. Consumer advocates, safety experts, and roboticists have expressed concern that mixing self-driving cars with human drivers could be dangerous. Recent field experiments in Tucson, Arizona offer a surprisingly optimistic outlook. Autonomous vehicles help minimize stop-and-go traffic, which is a bad habit that we sloppy humans perpetuate.

"Our experiments show that with as few as 5% of vehicles being automated and carefully controlled, we can eliminate stop-and-go waves caused by human driving behavior," said Daniel B. Work, assistant professor at the University of Illinois at Urbana-Champaign, a lead researcher in the study.

Although there is an abundance of researchers figuring out how to build a self-driving car, nobody knows exactly how robotic cars will be introduced to public roads. Most industry stakeholders agree that eventually, when all cars are fully autonomous there will be major safety improvements. An often-cited statistic to back this claim is that 94% of fatal car accidents are caused by humans.

Until all cars are autonomous, we will still have traffic jams caused by road construction, accidents, and rubbernecking. But the new research reveals that even by incrementally adding semi-autonomous features such as adaptive cruise control into today's cars, traffic can improve.

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