Everything changes with self-driving cars, including traditional traffic lights. What a loss to history! These signals go back more than 150 years and were originally designed for horse carriages. The very first one, invented by a J.P. Knight, was installed in 1868 near the House of Commons in London.

traffic lightIn downtown Seattle in1939, traffic waits for the light. By this time, we couldn't imagine modern intersections without signals. (Photo: Seattle Municipal Archives/flickr)

Things were sleepy for a while, then a lot of inventors had eureka moments: Earnest Sirrine of Chicago (first automatically controlled signal, 1910); Lester Wire of Salt Lake City (red and green lights, 1912); James Hoge of Cleveland (with the words “stop” and “move”); and William Ghiglieri of San Francisco (capable of manual or automatic operation); William Potts of Detroit (the first to add a yellow light, 1920).

Autonomous vehicles don’t need visual signals to know when they can hit the accelerator. Instead, they’ll take in constant wireless signals from their environment — the other cars, pedestrians, cyclists, animals on the road. Intersections will be just one more challenge for them.

Four-way stops will still be one of the biggest challenges for autonomy, because of possible sensory overload. Don’t worry, though, the scientists are working on it.

Light Traffic intersection control Some cars will stack up at the intersection, but others will just barrel through, missing each other by inches. (Photo: MIT Senseable City Lab)

And you thought that having traffic lights use LED bulbs was a major advance! A team of researchers from MIT, the Swiss Institute of Technology and the Italian National Research Council is thinking ahead, and created a light-free system called “Light Traffic.” It uses sensors to control auto pilot cars as they approach a crossroads, stacking ‘em up in an orderly fashion. Says MIT:

This approach, based on slot-based intersections, is flexible and can be designed to accommodate pedestrian and bicycle crossing with vehicular traffic. The model provides a performance breakthrough: all safety requirements being equal, traffic efficiency is doubled with respect to current state-of-the-art traffic lights. With today's traffic volumes, queues would vanish and travel delays would be cut to almost zero.

Light Traffic intersection controlFuturists have long imagined automated traffic like this, but now we have the tech to make it happen. (Photo: MIT Senseable City Lab)

According to Carlo Ratti, director of MIT’s Senseable City Lab, “Traffic intersections are particularly complex spaces, because you have [at least] two flows of traffic competing for the same piece of real estate. A slot-based system moves the focus from the traffic flow level to the vehicle level. Ultimately, it’s a much more efficient system, because vehicles will get to an intersection exactly when there is a slot available to them.”

To see how it works, watch the video and be amazed — traffic just whizzes through the intersection, barely slowing down. It looks suicidal at first, but then you realize it’s orderly, like some kind of automated shipping system operated by robots. Once you’ve seen a fully articulated, computer-controlled arm install a windshield, you’ll know that these never-take-a-coffee-break (or demand a raise) robots are the wave of the future.

Here's the concept on video:

Jim Motavalli ( @jmotavalli ) writes about cars, technology and the environmental world to anyone curious enough to ask.

Say goodbye to traffic lights
Four-way stops will be one of the biggest challenges for self-driving cars, because of possible sensory overload.