Can your car tell you when the light's about to change?

A Couple of Reasons Why This Might Matter

Traffic light information is displayed on Audi's Driver Information System (DIS) located in the vehicle's central instrument cluster.
Traffic light information is displayed on Audi's Driver Information System (DIS) located in the vehicle's central instrument cluster.
(Courtesy of Audi AG)

Beyond helping those drivers who simply cannot be bothered to notice the most basic traffic information to avoid running over pedestrians at every intersection, there are some practical advantages of Project Traffic Light Online, too. First, it helps save gas. Starting and stopping the vehicle sucks up gas, while cruising along at a steady speed, whether that's 25 miles per hour (40.2 kilometers per hour) or 65 miles per hour (104.6 kilometers per hour), uses less fuel. So Audi's system, according to Zweck, "recommends an optimal speed within reasonable limits to reach a green traffic light. This avoids unnecessary stops and speeding and thus improves fuel efficiency." That's engineer-speak for the system telling you that if you roll along at 32.7 miles per hour (52.6 kilometers per hour), you'll hit green lights all the way down this street. If you don't have to stop for a light or mash the gas to make the green, you use less fuel.

The second practical advantage of the system is to smooth out traffic flow. If everyone is flowing through traffic lights at optimal speed within reasonable limits, there are likely to be fewer waits at red lights and fewer fender benders that snarl up entire intersections. But if only a few Audi models are equipped with the ability to read traffic light data, won't those schmucks in the unhelpful cars muck everything up anyway? Not according to Zweck, who said, "Research suggests that improved traffic flow can be measured when 5 to 10 percent of all vehicles are equipped with this technology." That's still a lot of cars. In 2013, there were nearly 250 million cars on the road, which means 12.5 million cars, at a minimum, would have to be talking to the traffic signals.

While this is another step toward the driverless cars of the future we've been hearing so much about, Zweck noted that Project Traffic Light Online was developed independently of Audi's self-driving A6 Avant, which was at the 2013 Consumer Electronics Show. There are a couple of test cars in a small handful of cities worldwide, but there's no projected on-sale date for red-light reading Audis yet.

Author's Note: Can your car tell you when the light's about to change?

I have an uncle who, when I was a kid, timed all the lights along a nearby city's main drag. He calculated the optimal speed for making every green light in this long string of traffic signals. He would express dismay -- but never outrage -- at drivers who were unaware of this optimal speed and travelled too slowly by a couple miles per hour, thereby wrecking his green-light run. He would very much admire Michael Zweck and his team's work, I think. Or maybe he'd think they took all the fun and personal satisfaction out of figuring it out.

In any case, Audi and Zweck make a convincing case for smoothing out the traffic flow. I can't count the number of times some idiot who was definitely not me thought she could make a green light if she sped up, only to realize she could not make it and, after checking the rear view to make sure there wasn't anyone too close to her bumper, engaging the always helpful ABS. But that was very much not me. At all.

Related Articles


  • Edelstein, Stephen. "Audi Traffic Light Recognition Could Save Time and Fuel." Popular Science. March 12, 2014. (March 26, 2014)
  • Experian Automotive. "Total number of vehicles on the road reaches highest level since 2008." PR Newswire. Nov. 4, 2013. (April 3, 2014)
  • New York Daily News. "Audi shows off self-driving A6 Avant and RS7 Sportback." Jan. 28, 2013. (March 26, 2014)
  • Zweck, Michael. Audi electronics engineer. E-mail interview conducted on April 2, 2014.